Archive for November, 2007

Auto Engine Misfire Codes:Auto Engine Tune Ups,Ignition Coil,Knock Sensor,Spark plugs,Crank Shaft Position Sensor-P0340,p0345-Houston,Tx

Saturday, November 24th, 2007

Current Trends for Ignition Systems


By Larry Carley, Technical EditorAs automotive technology moves forward, ignition systems are becoming more and more entangled with other systems on the engine. The current generation Nissan Maxima 3.5L V6, which was introduced in 2004, has a fairly conventional coil-on-plug (COP) ignition system. The individual coils are driven by the powertrain control module (PCM) using the input signal from the crankshaft position (CKP) sensor as the primary timing trigger. But what makes this system different from others you may be familiar with is that the PCM also uses input signals from the two camshaft position (CMP) sensors (one for each cylinder bank) to modify spark timing. Nissan also refers to the camshaft position sensors as “PHASE” sensors (for cam phasing, I assume).Spark timing on the 3.5L engine is nonadjustable and is controlled by the computer. You can read the timing on a scan tool, or if you prefer to do things the old fashioned way, you can actually check the spark timing on this engine with a timing light. The catch is you first have to remove the #1 COP ignition coil (the first cylinder on the rear bank) and insert a plug wire between the coil and spark plug. Then you can clamp your inductive pickup onto the plug wire and observe the timing marks on the crankshaft pulley. The timing spec for this engine is 15° plus or minus 5° BTDC (Before Top Dead Center). The idle spark timing can vary quite a bit depending on what the PCM thinks the engine needs based on operating conditions.So what happens if you check the timing and see that it’s outside the specs? Nissan has a special procedure for this called the “Idle Air Volume Learning” procedure. The 2004 and newer 3.5L V6 engines are throttle-by-wire, so the PCM will vary spark timing according to throttle position, idle speed and airflow into the engine. Nissan says the Idle Air Volume Learning procedure must be done anytime the PCM or electronic throttle control actuator is replaced, or anytime the ignition timing or idle speed are not within specifications. Nissan also recommends doing this procedure anytime an engine has a stalling problem or an erratic idle issue.Before you can do this procedure, the engine and transmission fluid must be warm. The coolant temperature should be above 158° F, and the vehicle should be driven for 10 minutes or more to warm up the transmission fluid. The charging system must be putting out 12.9 volts or more at idle, the gear shift selector must be in Park or Neutral, and all the lights and accessories (A/C, heater, radio, etc.) must be off. On vehicles with daytime headlights, applying the parking brake before the engine is started will prevent the headlamps from turning on.The easiest way to do the Idle Air Volume Learning procedure is with the Nissan Consult-II factory scan tool. All you do is select the test, touch Start and wait until the scan tool displays “CMPLT” for test complete. You can then rev up the engine a couple of times and recheck the timing and idle speed to make sure they are now within specifications.There is also a manual procedure for doing the Idle Air Volume Learning procedure if you don’t have a Nissan factory scan tool handy:

  1. With the engine and transmission warmed up, turn off the key and wait at least 10 seconds.
  2. Confirm that accelerator pedal is fully released, turn on the ignition switch and wait three seconds.
  3. Repeat the following quickly five times within five seconds:– Fully depress the accelerator pedal.– Fully release the accelerator pedal.
  4. Wait seven seconds, then fully depress the accelerator pedal and hold it for approximately 20 seconds until the MIL stops blinking and turns on.
  5. Fully release the accelerator pedal within three seconds after the MIL turns on.
  6. Start engine and let it idle.
  7. Wait 20 seconds.
  8. Rev up the engine two or three times and make sure that idle speed is 625 rpm plus or minus 50 rpm, and that spark timing is 15° plus or minus 5° BTDC.

If idle speed or ignition timing are not within specs, you’ve got a problem. Inspect the throttle valve to make sure it is fully closed. Check the PCV valve (make sure it rattles and is sucking vacuum). Check for any air leaks downstream of the throttle. If no problems are found, check all the wiring harness connectors to the throttle actuator, and check throttle position sensor and airflow sensors for possible faults.Misfire Codes
If the MIL is on and you find a P030X misfire code for a specific cylinder, the fault may be a fouled spark, a bad ignition coil or even a burned valve. See coil locations in Figure 1. Chances are the misfire might be a bad coil since Nissan has had a history of coil issues on the previous generation Maxima.

On the 2001-’03 Maximas, coil failures at relative low mileages (60,000 to 70,000 miles) are not uncommon. Nissan has not recognized the problem and has not issued a technical service bulletin about the coil failures. But they do recommend replacing all six coils if one fails. Why? Because when one coil fails, chances are another will fail not too far down the road. The coils cost about $85 each, and the part number is 224488J115.
These earlier generation coils also have had a problem with RFI (Radio Frequency Interference) causing static on the car radio. Nissan issued a bulletin NTB01-073B, dated March 1, 2002, covering 2002 Maxima, Altima and Sentra models.
The bulletin says the cause of a steady, rhythmic ticking or popping noise in the radio speakers that follows engine speed on certain FM radio stations can be caused by the ignition coil resistors (which are located inside the ignition coil tube that fits down over the spark plug).
To get to the coils on the 2002 engines, it is only necessary to separate the intake collector from the intake manifold as shown in Figure 2 on page 18. You do not have to remove the throttle body from the intake collector or drain the radiator. The resistors inside the coil tubes can then be replaced by pulling the rubber boot away from the ignition coil. Then twist and pull the ignition coil tube to separate it from the coil. The old resistor assembly inside can then be replaced with the new resistor as shown in Figure 3.
On the current generation Maximas, a different style of COP coil is used and failures have not been an issue (at least not yet) — which is a good thing because the coils are harder to replace. If you have to change one (or all six), here’s the procedure:

  1. Remove the plastic engine cover.
  2. Drain the radiator.
  3. Disconnect the mass air flow sensor electrical connector and remove the air cleaner assembly and air intake tubes.
  4. Remove the intake manifold collector, gasket and electric throttle control actuator.
  5. Replace the coil(s).

The ignition coils for the current Maximas are also about $85 each, and the standard labor to replace all six is 2.2 hours according to Nissan. The part number is 224488J115.Spark Plugs
The factory-installed spark plugs in the 2004 and up Maximas are PLFR5A-11 NGK platinum plugs with a 100,000-mile service interval. The electrode gap is 1.1 mm (0.043”). If a cylinder misfire is due to a worn, fouled or shorted spark plug, you still have to go through the same coil removal procedure because the plugs are buried down under the coils. You’ll need a magnetic spark plug socket and a long extension to extract them from the holes in the valve covers.
Reading the plugs is still a useful diagnostic practice for seeing what’s actually going on inside the combustion chamber. And, Nissan’s 3.5 V6 engines have a pretty simple firing order. See Figure 4. If a plug is wet, it means the coil isn’t firing. If the electrodes and insulator on the plug are covered with black soot, the cylinder is running too rich (possibly a leaky fuel injector, or maybe a sticky fuel pressure regulator or bad O2 sensor if all the plugs are carbon fouled). If the plugs have wet, oily carbon deposits, the engine is burning oil. The most likely cause would be worn intake valve guides and seals, or possibly worn or broken piston rings. Oil burning can not only foul the plugs, but also cause a buildup of heavy carbon deposits on the intake valves and inside the combustion chamber. This, in turn, may cause hesitation problems when accelerating, or possibly spark knock (detonation).Knock Sensor
The Maxima engine requires premium fuel, but will also run on lower octane gas because it has a knock sensor (located in the middle top of the engine under the intake plenum). If the knock sensor detects spark knock when the engine is under load, it will send a signal to the PCM to retard spark timing. There shouldn’t be any spark knock if the knock sensor is doing it’s job and there is not too heavy a buildup of carbon in the combustion chambers or on the tops of the pistons. If an engine has a spark knock issue, therefore, the problem might be a defective knock sensor or a heavy buildup of carbon in the engine. If switching to 91 octane gas doesn’t eliminate the problem, and the knock sensor is generating a signal, the carbon needs to be removed from the engine with a Top Cleaner treatment.
You can check the knock sensor by looking at the scan tool to see if is generating a signal, or by measuring the resistance between knock sensor terminal 1 and ground. A good knock sensor should measure 532-588 kOhms at room temperature. Nissan says to handle the knock sensor carefully because it can be damaged if it is dropped onto a hard floor. If you need to replace a knock sensor on a 2004 or newer Maxima, the part number is 220607S000. The part costs about $95 and takes 2.6 hours labor to replace because of its buried location (the top of the intake manifold has to come off).No Start, No Spark
If you encounter a Maxima that won’t start, the fault might be no spark or it might be no fuel. A quick way to find out is to spray some starting fluid into the throttle or air intake and see if the engine starts. If it starts and runs a few seconds, then dies, the problem is no fuel (bad fuel pump, fuel pump relay or a leaky fuel pressure regulator). If it does not start, the PCM may not be getting a good rpm signal from the crank position sensor.
The crank sensor, which Nissan refers to as a “POS” (position sensor), is located on the oil pan, is a magnetic sensor with a Hall effect chip inside that converts the AC signal to a digital rpm signal. There are no resistance specs for this sensor other than zero (on) and infinite (off). You can use your scan tool or a scope to see if the sensor is generating an rpm signal when the engine is cranking, or a noid light to check for a digital signal output. If the sensor is bad and you need a new one, the part number is 23731AL60C and the cost is about $70.
Another component in the ignition system that may cause a no start because of no spark is the ignition system relay (located in the underhood relay center along with the fuel pump, cooling fan, starter, PCM and headlight relays). An open relay will kill power to the ignition coils.
The ignition system also has a condenser in the circuit that runs from the PCM relay to the ignition coils. A shorted condenser could also ground out the ignition circuit causing a no start. The condenser can be checked by measuring the resistance between terminals 1 and 2. A good condenser should have 1M Ohms or more of resistance.Nissan has a bulletin out for a hard hot starting problem on the 3.5L V6 in the early 2004 Maxima and Quest, and 2003-’04 Altima models. The symptom it describes is an engine that starts OK cold, but is hard to start after it has been driven. The check engine light may or may not be on, and DTC codes P0340 (CMP sensor bank 1) and/or P0345 (CMP sensor bank 2) may be present. See Figure 5. In any event, Nissan says the fix is to replace one or both camshaft position sensors. The part number of the rear bank (bank 1) CMP sensor is 23731-65906, and the front bank (bank 2) CMP sensor is 23731-Al616. The CMP sensors are the same type as the CKP sensor, and also cost about $70 each.

Auto Car Heater&Engine Blower Motor&Automobile Thermostat Service-Houston,Tx

Saturday, November 24th, 2007

Heater Service – A Year-Round Opportunity

By Larry Carley Nothing is more annoying than a heater that blows cold air – except maybe one that leaks. So if you’re dealing with a heater problem, be it a leaker or one that doesn’t seem to put out much warmth, keep reading because this article can help you solve your heater blues. Before we get into troubleshooting heater problems, let’s talk about the heater itself. The heater core is like a mini-radiator. It has inlet and outlet pipes and a finned copper or aluminum core through which hot coolant from the engine circulates. The heater core is located inside the HVAC plenum under the dash and usually on the passenger’s side of the box. When hot coolant from the engine flows through the heater core, the core gets hot and heats the air that’s forced through it by the blower motor. Generally speaking, a heater should put out air that’s at least 70° hotter than the outside temperature. So if it’s 30° outside, your heater should put out at least 100° F. The hot coolant flows from the engine to the heater core through the “inlet” hose. After circulating through the core, the coolant returns to the water pump through the “outlet” or “return” hose. Both the inlet and outlet return hoses should feel hot when the engine is at normal operating temperature and the heater is on. In the inlet hose you may find a “heater control valve” that blocks the flow of coolant to the heater when the heater isn’t needed (when running your air conditioner on maximum, for example). Some older heater control valves are cable or vacuum operated, but most of the newer ones (when used) are electronic. Most heater control valves are open all the time unless vacuum or power is applied. This means hot coolant circulates through the heater core even when the heater isn’t being used. This is done for several reasons. One is safety. In the event the heater valve fails (doesn’t close when vacuum is applied) you still have heat to defrost the windows for safe cold-weather driving. Some heater control valves are “thermostatically controlled” with a capillary tube that extends into the heater air outlet. The capillary tube reacts to changes in the heater’s output. This regulates the opening and closing of the control valve to maintain a more consistent level of heater performance. Another method of regulating the heater’s output is to control air flow through it. This is done two ways: by changing the blower speed and by opening and changing the position of the “blend doors” that route air through the heater core and A/C evaporator inside the HVAC housing. On vehicles without factory air conditioning, sliding the heat selector control switch to the off position closes a door that blocks the flow of air into the heater core. Even if the blower is turned on, no heat will come out because the air inlet is closed. On vehicles with factory air conditioning, a second “blend” door is usually used to route some air through the heater core and some through the A/C evaporator, depending on the temperature range selected. Sliding or tuning the temperature range knob all the way to the cold position closes the blend door so all air is routed around the heater core and through the A/C for maximum cooling. Sliding or turning the temperature knob to a midway position between hot and cold opens the blend door so warm air is mixed with cold to take the chill off the A/C. A third air control door is used to reroute air to the defrosters. On vehicles with automatic temperature control (ATC) systems, the ATC module figures out the best door positions and positions them accordingly to deliver heat or cooling. If the vehicle has a dual-zone system, there may be a separate heater core for each side. Or, the ATC system may use additional blend doors to route different amounts of heating or cooling to each side. The blower motor, which blows air through both the heater and air conditioner on vehicles with factory A/C, is wired to a “resistor unit” (usually mounted on the outside of the heater box or plenum) to reduce circuit voltage so the motor will run at the desired speed. Power to the motor may be supplied through a separate relay hidden somewhere under the dash. Blower Problems If the blower motor doesn’t work (no sound), it probably means the motor is bad and needs to be replaced unless debris has jammed the blower fan or there is an electrical fault such as a blown fuse, bad relay, switch or resistor, or loose wire. A blown fuse, by the way, is a symptom not a cause. A blown heater fuse means the circuit overloaded for some reason. Replace the fuse with one of the same amp capacity (never one with a higher rating because doing so may allow the wires to get dangerously hot). If the new fuse blows as soon as the blower is turned on, you’ve confirmed an electrical short circuit in the wiring or motor that needs to be investigated further. If the fuse lasts awhile and then blows again, the motor is probably running hot due to worn brushes and/or bushings and needs to be replaced. The motor itself can be checked by using a pair of jumper wires to see if it works. Connect one wire to ground and the other to a source of battery voltage. If the motor does nothing, it needs to be replaced. Suppose you have a blower motor that runs (you can hear it) but no air comes out of the ducts. The problem here is a jammed or inoperative air flow control or blend door (this applies to defrosters that don’t work, also). Try changing the temperature setting. If you don’t hear movement from the doors inside the HVAC unit, you’ll have to troubleshoot the control system. With ATC systems, you’ll need a scan tool to access the self-diagnostics and/or to run door motor checks. Doors also can be jammed by objects that have been placed on the dash and have disappeared down the defroster ducts. The cure here is to extract the object from the plenum by fishing through the heater outlet with a coat hanger or magnet – or removing the plenum. With vacuum-controlled doors, the most common reasons for failure are leaky or loose vacuum hoses, or defective diaphragms in the little vacuum motors that move the doors. You can check for vacuum by starting the engine and disconnecting the small hose that goes to the vacuum motor that works one of the doors. If you feel vacuum or hear a hissing sound when trying different temperature settings, the vacuum source is okay and the problem is a bad vacuum motor. You also can test a vacuum motor by applying vacuum to it with a hand-held pump to see if it moves and holds vacuum (otherwise it should be replaced). If there’s no vacuum, check for leaky vacuum hose connections, a defective temperature control switch, or a leaky vacuum reservoir under the dash or in the engine compartment. Most defroster problems (no air to the windshield) are also caused by inoperative air flow control doors, or loose, deteriorated or damaged ducts. Another often overlooked cause of poor blower performance, heating, cooling and defrosting is a plugged cabin air filter. These filters are used on many later-model vehicles and should be changed according to the maintenance schedule in the owner’s manual. Filters that have activated charcoal to absorb odors should be replaced yearly. Dust filters should be replaced every two to three years as a rule. Cabin air filters can usually be found under or behind the glove box, or at the base of the windshield where air enters the HVAC system through the cowl duct. Heater Woes When no or low heater output is not due to a blower problem (plenty of air coming out of the ducts but the air isn’t hot), the list of possible causes include:

  • Blocked circulation through the heater core – due to either sediment in the core or a defective heater control valve. Feel the heater inlet and outlet hoses while the engine is idling and warm, and the heater temperature control is on hot. The hose will not feel hot on the heater side of the valve if the valve is shut. The outlet hose will also not be hot. With cable-operated control valves, check the cable for sticking, slipping (loose mounting bracket) or misadjustment. With valves that are vacuum operated, there should be no vacuum to the valve when the heater is on (except for those that are normally closed and need vacuum to open). Someone may have misrouted a vacuum hose. With electronic heater control valves, check for voltage at the valve. It should have voltage when the temperature controls are set for maximum heat. If the solenoid fails to move when voltage is applied, it is defective and needs to be replaced. If the heater core appears to be plugged, the inlet hose may feel hot up to the core but the outlet hose will remain cool. Reverse-flushing the core (forcing water into the heater outlet pipe with a garden hose) can sometimes open up a blockage, but usually the core will have to be removed for cleaning or replacement. Air pockets in the heater core also can interfere with proper coolant circulation. It’s akin to losing the prime with a siphon pump. Air pockets form when the coolant level is low or when the cooling system is not properly filled after draining.
  • Low coolant level – usually the result of overheating or a leak. A low coolant level can starve the heater resulting in little or no heat output. To check the level, pay no attention to the overflow reservoir. Shut the engine off, wait 20 minutes or so for the engine to cool, then carefully open the radiator cap. Allow any residual pressure to vent itself completely before removing the cap. If the coolant level inside the radiator is low, adding coolant won’t fix the problem if there’s a leak. Inspect the water pump, hose connections, radiator and engine for coolant leaks. Also pressure-test the cooling system and radiator cap to check for internal coolant leaks due to a bad head gasket or cracks in the cylinder head. Check the pressure rating on the cap to see that it’s correct for the application, and carefully inspect the cap’s gasket and spring. Replace the cap if it can’t hold its rated pressure or has the wrong pressure rating for the application. Cooling system neglect can allow internal corrosion to eat small holes in the heater core or where the pipes are soldered to the end tank. Leaks also can be caused by sediment circulating in the cooling system. Sediment is abrasive and will literally wear holes in the heater core. A leaky core will often drip coolant into the passenger compartment (don’t confuse this with water condensation that may be coming from the A/C evaporator). Leaks also can develop from fatigue cracks in the inlet and outlet pipes. This is caused by flexing of the heater hoses from engine torque and/or vibration. Adding sealer to the cooling system may provide a temporary fix, but the long-term cure is to replace the heater core.
  • Defective or missing thermostat that allows the engine to run too cool. Maintaining the correct engine operating temperature (usually 200° to 220° F.) is essential not only for good heater output but also for good fuel mileage and proper operation of various emissions control functions. If the temperature gauge on the dash reads low, the engine is slow to warm up or you can feel coolant rushing through the upper radiator hose when the engine is cold started, the thermostat is stuck open (or missing) and needs to be replaced. Be sure to install a thermostat that’s rated at the same temperature as the original (usually 195° on late-model cars).
  • Weak water pump that fails to circulate an adequate amount of coolant to the heater. This problem also will cause the engine to overheat. If the problem isn’t due to a slipping drive belt, the pump probably has an eroded or separated impeller.

Heater Core R&R Access to the heater core depends on its location. In most vehicles, replacing the core is a time-consuming, back-twisting, neck-wrenching job because of its buried location under the dash. R&R times on many jobs can run six to eight hours or more. So you want to be absolutely sure of your diagnosis before you tear the dash and HVAC system apart. Once you have the HVAC system opened up, you also should check the condition of the evaporator. If the A/C system has been leaking refrigerant, chances are there might be pinholes in the evaporator. Now would be a good time to replace it if replacement is needed. Installation After the heater core has been replaced, refill the cooling system with a fresh 50/50 mixture of antifreeze and clean water if the coolant is more than two years old (conventional coolant) or five years old (extended-life coolant). If the old coolant is extremely dirty or contains sediment, you should thoroughly flush the cooling system not once but several times to remove all the debris. Even a little bit of sediment that remains in the system can shorten the life of the heater core and water pump. Refilling some cooling systems can be tricky, particularly on some vehicles with front-wheel drive or rear-mounted engines. Air pockets tend to form in long heater hoses and heaters that are mounted higher than the radiator. To help vent the trapped air, some vehicles have “bleeder” valves on the hoses. Opening the valves allows air to escape as the system is filled. The valves are then closed when coolant reaches their level. On vehicles that lack these special bleeder valves, it may be necessary to temporarily loosen the heater outlet hose so air can bleed out as the system is filled. Another trick is to raise the front end of the vehicle off the ground so the radiator filler opening will be the highest point in the system. The condition of the heater and radiator hoses as well as the drive belts also should be inspected at this time. Pinch the hoses. Any that feel hard, mushy, are age cracked or chaffed should be replaced. New clamps are also recommended. Most experts say you should replace the hoses and belts if they’re more than four years old. If the heater core is being replaced because of cracked inlet or outlet pipes, the heater hoses may have to be lengthened and/or rerouted or supported with supplemental brackets to minimize flexing and the transmission of engine vibrations to the heater pipes.

Auto Engine Starting-Charging System Problems-Diagnosis -Repair-Alternator,Car Battery,Starter,Engine No Start issues-Houston,Tx

Saturday, November 24th, 2007

STARTING/CHARGING
SYSTEM DIAGNOSIS





Fixing Faults the First Time Eliminates Comebacks & Returnsby Larry Carley, Technical Editor

How many starters and alternators are replaced unnecessarily every year because of misdiagnosis? Nobody knows for sure, but suppliers of both new and remanufactured rotating electrical parts tell us more than half of their warranty returns have “no fault found” when the parts are examined. Many of these returns are from DIYers who lack diagnostic know-how, but some are from professional technicians who apparently lack the same skills.The point we want to stress here is the importance of diagnosing starting and charging problems before any parts are replaced. If you correctly perform the diagnosis, you’ll fix the fault the first time and won’t have to worry about comebacks, returns or your reputation. You’ll also save your customers money and yourself the hassle of trying to fix the same problem again.IT ALL STARTS WITH THE BATTERY
Let’s look at a typical no-start scenario where the engine fails to crank when the motorist tries to start his car. The first thing that usually needs to be determined is whether or not a rundown battery is the reason for the engine not cranking. Starters pull a lot of amps when they crank an engine, and if the battery is low, there may not be enough current available for the starter to overcome the compression, spring pressure and friction within the engine. If the starter cranks normally with a jump-start, though, you can rule out a starter problem right away. The next thing to investigate would be the battery.Did the battery run down because the motorist left his lights on? Has the car been sitting a long time? Is it only used infrequently for short trips? Is the charging system putting out enough amps to keep the battery fully charged? Is there a higher-than-normal key-off current drain on the battery that’s running it down? Is the battery no good?
These are all concerns that can be easily answered by asking the vehicle owner a few questions and performing a few simple tests. If the motorist did not leave his lights on, and the vehicle has been driven daily for at least 20 minutes or more, chances are the car has a charging problem, a bad battery, or loose or corroded battery cable connections.A visual inspection of the battery connections might reveal something if you see signs of corrosion or the cable clamps are loose or damaged. The battery’s state of charge can be tested with a voltmeter. A fully charged battery should read 12.6 volts. Less than 12.4 volts means it’s low and needs to be recharged.The charging voltage can be checked at the battery with the engine idling. Most charging systems will put out 13.5 to 14.5 volts at idle, depending on the temperature and the battery’s level of charge. Less than 13.5 volts would indicate a charging problem.If the charging system is putting out normal voltage, the battery should then be load tested or checked with an electronic conductance tester to determine if it’s good or bad (Note: A traditional load tester won’t give accurate test results unless the battery is first recharged. This isn’t the case with conductance testers because the test results do not depend on the battery’s level of charge.) Average battery life is only about four to five years at best, and can be as little as three years in a hot climate.If the battery tests bad, the vehicle obviously needs a new battery. Replacement batteries should always have the same or higher cold cranking amp (CCA) rating as the original, and be fully charged before they are installed in a vehicle. And don’t forget to attach a backup power supply before disconnecting the old battery on cars where loss of keep alive memory data can cause problems. But what if the battery tests good and the charging system is working normally? Then what? The next check would be to look for a higher-than-normal key-off current drain.NORMAL AND ABNORMAL CURRENT DRAIN
When the key is turned off, the electrical load on the battery doesn’t stop. There is always a small load on the battery to maintain the “keep alive” memories in the powertrain control module (PCM) and other modules. Many modules have internal timers that either turn off the module to put it into a “sleep mode,” or power down the module to a “standby mode” after a certain length of time when the key is turned off. Some of these modules power down in steps and time out at different rates.
As a rule, the key-off current drain on most late-model vehicles should be less than 50 milliamps (mA), one hour after the vehicle has been shut off and left undisturbed.The key-off drain can be measured with a milliamp amp probe or an ammeter. A clamp-on amp probe is the better choice here because you don’t have to disconnect a battery cable as you would if you use an ammeter. Disconnecting the battery on many late-model cars without first connecting a battery backup to maintain the keep alive module memories can create additional problems. Any disruption in power, even for a split second, can cause the PCM and other modules to forget learned values and other key settings. This, in turn, may require using a scan tool to reset or recalibrate certain systems. Don’t make extra work for yourself by forgetting this key bit of information.When measuring a key-off current drain, keep in mind that opening a door, the trunk or turning anything on may wake up certain modules and increase the key-off current drain reading.If the key-off current drain is higher than normal, the problem may be a light or module that’s staying on, or a relay that is not switching off. Finding the fault usually means pulling fuses one by one until the current reading drops down to a normal reading.STARTER CIRCUIT
Now, let’s say the battery tests good, the charging system is working normally and there are no abnormal current drains on the battery. But the engine won’t crank when you try to start it. Nothing happens when you turn the key to the start position (or press the start button). A no crank with a good battery means there is some kind of problem in the starter circuit.
Voltage may not be reaching the starter relay, the starter solenoid or the starter motor. The cause may be a bad ignition switch, an open park/neutral safety switch (if the vehicle has an automatic transmission) or an open clutch pedal safety switch (if it has a manual transmission).Diagnosis should begin at the starter relay. If the relay is not receiving battery voltage when the key is turned to start (or the start button is pushed), the fault is upstream of the relay. You would use a voltmeter or test light to find out where the voltage is not getting through. Is there voltage to the ignition switch or start button? Does voltage flow from the switch or button when you try to start the engine? Is there voltage to the park/neutral or clutch pedal safety switch? Does the switch pass voltage when it should? If the switches are all OK, but there is no voltage to the relay, the fault would be in the wiring or a loose or corroded wiring connector.If power is reaching the relay but nothing is happening, you can test the relay with an ohmmeter (refer to the test values and terminal connections provided by the vehicle manufacturer), or you can simply swap or replace the relay to see if that solves the problem.If the fault is not the relay, the next check would be the circuit between the relay and starter solenoid or starter (depending on how the system is wired). Loose or corroded connections can strangle the flow of current to the starter. Using a voltmeter to do some voltage drop tests can help you find bad connections.VOLTAGE DROP TESTING
A voltage drop test is the only effective way to find excessive resistance in high-amperage circuits. As a rule, you should see no more than 0.5-volt drop across a high-current connection, and no more than 0.1 volts across a low-current connection. Ideally, you should see no voltage drop at all.
To perform a voltage drop test, the circuit needs to be on with current flowing through it. You then use a digital voltmeter (DVM) to measure the voltage drop across each connection in the live circuit. Voltage always follows the path of least resistance, so if the connection being tested has too much resistance, some of the voltage will flow through the voltmeter and create a voltage reading.If a connection is good (clean and tight with no resistance), you should see little or no voltage drop (zero to less than 0.1 volts). But if you find more than a few tenths of a volt drop, it indicates resistance and a need to clean and tighten the connection.It’s amazing how many times bad connections are overlooked because they “appear” to be OK. But appearances are often deceiving, and the only way to know for sure whether or not you have good connections in an electrical circuit is to measure the voltage drop across those connections. This applies to battery and ground cable connections, starter, solenoid and relay connections, and wiring harness connections.STARTER CHECKS
If voltage is reaching the starter but it isn’t cranking, or is cranking too slowly (most engines need to be cranked at least 250 rpm or faster to start), the problem is likely a bad starter.
Starter current draw can be tested on the vehicle or on a starter bench tester, and compared to specifications. A good starter will usually draw a current of 60 to 150 amps, depending on the size or power rating of the starter. Some “high-torque” starters may draw more amps, so always refer to the manufacturers’ test specifications. When a starter draws too much current, it may pull so much power from the battery that the ignition system won’t fire. The engine cranks but it won’t start because there is no spark (or too weak a spark).If the starter spins freely (up to several thousand rpm) and the amp draw is within specifications, it should be capable of starting the engine — unless there is a mechanical problem with the drive mechanism, drive gear or damaged teeth on the flywheel.If the starter does not spin freely, or draws an unusually high or low number of amps, the starter has reached the end of the road and needs to be replaced.An unusually high current draw and low free-turning speed typically indicate a shorted armature, grounded armature or field coils (possibly due to overheating from excessive cranking), or too much friction within the starter itself (dirty, worn or binding bearings or bushings, a bent armature shaft or contact between the armature and field coils). The magnets in permanent magnet starters can sometimes break or separate from the housing and drag against the armature.A starter that does not turn and draws a high current may have a ground in the terminal or field coils, or a frozen armature.Failure to spin and zero current draw indicates an open field circuit, open armature coils, defective brushes or a defective solenoid.Low free-turning speed combined with a low current draw indicates high internal resistance (bad connections, bad brushes, open field coils or armature windings).NO-CHARGE
If the charging system is not putting out enough current to keep the battery charged, the fault may be the alternator, the voltage regulator (or control circuit in the PCM depending on how voltage is regulated), or bad wiring connections.
If you don’t see at least 13.5 volts when you check charging voltage at the battery with the engine idling, check the wiring connections at the alternator — not just visually or by wiggling the wires or connectors, but check for excessive resistance by doing a voltage drop test. Many so-called alternator problems turn out to be nothing more than a bad connection at the alternator or a bad wiring harness. Alternator output can be tested on the vehicle or on a bench-tester. As a rule, an alternator should produce 90% or more of its rated output by 2,500 rpm. The charging curve will vary from one application to another, but if the output is less than specification, the alternator needs to be replaced.The fact that an alternator is producing voltage doesn’t mean it’s producing enough current to meet the vehicle’s electrical needs and keep the battery recharged. An alternator that is rated at 120 amps at 2,000 rpm, but is putting out only 40 or 50 amps, is a weak alternator that needs to be replaced.Common alternator problems include worn brushes and slip rings, shorts or opens in the stator or armature windings, broken or melted electrical connections, and bad diodes in the rectifier (diode trio). Diodes can fail from too much heat or current. The diodes in the back of the alternator convert alternating current (AC) to direct current (DC). If a diode shorts internally, some of the AC current can leak into the electrical system, causing a voltage pulsation. At the same time, a shorted diode may allow current to flow backward through the alternator causing the battery to run down when the engine is not running. When an alternator’s output is displayed on a digital storage oscilloscope, the waveform should look like a series of even humps. Missing humps would indicate bad diodes and a drop in current output.If an alternator tests bad, make sure the replacement alternator (new or reman) has the same or higher amp rating as the original. If the replacement comes with a pulley (some don’t), make sure it matches the original (same diameter, width and belt type). In some situations, you may want to recommend upgrading to a higher output alternator if the stock alternator can’t produce enough juice to power a high-wattage aftermarket sound system, off-road lights or other electrical accessories.

Auto/Car Engine Replacement-Short Block or Long Block-Automobile Head Gasket Job or Complete Engine Block-Houston,Tx

Wednesday, November 21st, 2007

Installing Confidence – Engine Installation Issues

By Brian Manley

In doing my research for this article, I began by listing all of the parts and procedures that I could think of that are used when performing an engine replacement. Then, I interviewed some local independent technicians who perform engine swaps occasionally. And lastly I spent time in a local machine shop that performs the entire operation from pulling the engine, through all of the machine work and reassembly, and finally installing and testing. When I finished my research, I was surprised at the importance of a few items that I had left off of my initial list!One way to perform an engine swap, while minimizing comebacks and providing the greatest service to your customer, is to use the following sequence:

  1. Properly evaluate the job.
  2. Using a checklist, record and attempt to verify the condition of all related parts.
  3. Using multiple information systems, locate all pertinent technical service bulletins.
  4. Remove the engine assembly.
  5. Disassemble the engine, while continuing to record necessary “extras.”
  6. Call the customer with the final estimate. Discuss the service bulletin updates and the root causes for the engine failure.
  7. Rebuild or purchase an engine (short or long block).
  8. Install the cylinder heads and “tin” the engine.
  9. Install the engine into the vehicle.
  10. Set-up, test-drive and re-check your job.

Evaluate The Job
While interviewing Don McDonald of Havana Machine in Aurora, CO, I was surprised at the thoroughness of their shop’s vehicle inspection sheet. Many items were no-brainers: tune-up parts, drive belts, clutch components, vacuum hoses and radiator hoses. But, have you ever considered the following during an engine replacement?• Molded hoses – Many of the smaller coolant hoses are overlooked.• Oil coolers – If the engine had metal moving through its oiling system due to bearing failure, consider replacing the oil cooler instead of simply flushing it out.• Belt tensioners and idler pulleys – Are the pulleys grooved or are the bearings worn out?• Fan shroud/Fan clutch – Is the full volume of air being pulled through the radiator?• Fan motor/Fan switch – The switch can be sold as easily as a new thermostat, but how hard do you push for a new cooling fan motor?

• Battery/AC generator/ Starter/Cables – What an opportunity to sell a complete starting and charging system diagnosis!

• Distributor – Are the bushings worn out? Is the AC pickup assembly or Hall effect sensor original?• Carburetor – There are still many of these on the road. Are the shaft bushings worn out, or does the carburetor need to be rebuilt? Does the base plate gasket include an EFE grid that has burned open?• Injectors – Are they original and do they require new seals?• Input sensors to the PCM, such as oxygen and coolant temperature – Do they need to be replaced?• Air conditioning system – Is it full? Does the compressor turn? Is there a major leak that could be repaired while the engine is out?• Air injection components – Are the pump, injection manifold and check valves intact?• CV axles/Drive shaft/U-joints – Visibly torn boots should be an easy sell.• Cruise control system – Did you activate it during the test drive?Don added that every engine job has its radiator sent to the radiator shop for evaluation. Many are found to be plugged or leaking. Also, every fuel-injected engine has the set of injectors flow-tested in-house by their driveability technician, and the customer is urged to replace them as a set if more than one fails the flow test.Technical Service Bulletins – Three Samples
I’m sure that you can think of a half-dozen TSBs that would be visited during an engine swap, but can you remember them all? It’s wise to search in as many databases as possible for any applicable TSBs, especially safety bulletins.
One example comes from the Engine Rebuilder’s Association (AERA) concerning oil coolers that are part of the radiator assembly on 1985-’97 4.3L GM engines. It stresses that whenever an engine has failed and subsequent bearing damage has resulted, it is recommended to replace or rebuild the oil cooler assembly. Small bearing particles and crankshaft material cannot be entirely removed from the cooler by simply flushing fluid through it. In some cases, if an engine cooler was reused after only flushing, multiple engine failures persisted until the cooler was replaced at the time of engine installation.Another bulletin from the AERA technical committee offers the following advice regarding the 1985-’96 Ford 1.9L “J” engines. Repeat piston failures have been reported shortly after a remanufactured engine was installed due to debris left inside the intake or exhaust manifold. Metallic debris was not completely eliminated during intake manifold cleaning.The intake manifold on this engine is a tuned port runner design, with a plenum located below the runners. If a piston shatters, some pieces can end up in the intake plenum or exhaust manifold. This manifold can only be thoroughly cleaned out of the car using a liquid cleaner and by rotating the part. A third AERA bulletin reminds engine builders that when installing the crankshaft damper for 1997-2002 GM 5.7L engines, you must use a new crankshaft damper bolt. This bolt includes a special pre-applied sealer that does not allow reuse. These engines also do not have a mark on either the crankshaft damper or the front cover to indicate the correct position for reassembly. The crankshaft does not have a keyway for the damper. Marking the cover and damper for reassembly may prevent possible vibration complaints after the engine is started up, as the damper may have been balanced at the factory.Remove and Disassemble The Engine
You and I probably have a few issues that Havana Machine doesn’t have to deal with. When they take an engine out of the vehicle, that very engine is machined, rebuilt and reinstalled. They don’t experience rebuilt engines that don’t have bolt holes drilled for the motor mount, or a crankshaft that won’t accept the inner diameter of your flex-plate. When you are buying a crate engine, make certain you compare every detail before dressing the new engine.
Regardless, careful attention must be paid to additional items as the engine is being disassembled. First and foremost is: Why did the engine fail? If the engine failed due to overheating, then a root cause must be found for high-running temperatures. Did the bearings fail due to lack of lubrication or was there lack of proper maintenance? If the crankshaft is broken, did the vibration damper fail or is it coming apart?That last example was a point of discussion at Havana Machine, as a new and old damper were sitting together on a technician’s bench. The tech had not noticed that the balancer had “walked” about a quarter-inch off its hub, making it scrape the timing cover upon reinstallation.An often-overlooked time waster is lurking in each stud or bolt that has either arrived in your stall in a snapped-off state, or twisted in two when you simply wanted to remove a manifold. The process of removing a broken-off bolt is a skill that must be charged for – especially when doing so saves a critical piece of expensive casting. Also, pay attention to sub-standard grades of nuts and bolts that have latched onto the engine over the years, and add these to the parts order. Building The Long Block
OK, up until this point we’ve been rippin’ and tearin’ an engine apart and writin’ stuff down on a check sheet. Now we’ve got to be certain that we’re focused on the job at hand, ‘cause it’s painful when you have to tear an engine due to head gaskets living on the wrong side of the block. Not only do we have to worry about the normal rebuilding of the engine, we have to be certain that there are no service bulletins that pertain to the long block itself.
One example is the lower intake manifolds on Ford engines that do not fit correctly after machining. To reduce the likelihood of coolant contamination of engine oil, a revised, thicker intake gasket is now available for the 3.8L and 4.2L car and truck engines.Once the cylinder heads and manifolds are torqued down, then it’s time to “tin” the engine. When installing the oil pan, timing cover, valve covers and any other component that seals fluids or pressures, you must make the right choice of gasket or sealer right now. Surfaces must be clean, dry and flat. Beware of surface conditioning discs that can grind away metal, leaving a gouge in a casting. When choosing a gasket material, many techs use the gaskets that come in the engine overhaul kit. Others prefer to “upgrade” certain gaskets to other materials, or substitute RTV in place of a solid gasket. Experience usually dictates which material will stand the test of time.All bolts that thread into the block must be capable of applying the correct torque to its mating piece. If a bolt is threading into a blind hole, make certain that the threads are clean, and put a drop of oil on the treads and under the bolt head. If the bolt opens into a coolant passage, as some manifold, cylinder head or water pump bolts do, then you must apply a liquid sealant to the threads before installing. Failure to do this will allow coolant to wick up the threads and leak past.Sean Kuchera, manager at Havana Machine, relayed a great tip for engine oil pumps. After experiencing an oil pump screen that backed out of its pump, they now tack-weld the pump screen to the oil pumps before bolting the pans on, to assure that it will never move.Toss It Back In
Now that the engine is painted, dressed and run on the engine test stand (if you have one), then you’re ready to toss that puppy back in place. Mounts, hoses, bell-housing bolts, brackets and pumps are all reattached. Are you like me and let the air ratchet dead head to properly torque these fasteners? Well, I do still torque critical ones, and I use blue Loctite on pulley bolts or other threads that I want to ensure stay locked.
If the engine cradle was removed to get the engine out, then cradle alignment may be an issue. Many have positive pins that ensure almost exact replacement of the cradle, but some do not. Alignment should be checked after a cradle has been removed. Gentlemen (and Ladies) … Start Your Engines!
Once an engine is installed at Havana Machine, a comprehensive Pre-Delivery Inspection is performed. All fluids are filled and burped, clutch or transmissions kick-down cables are adjusted, and a five-gas exhaust analysis is performed.In our emissions test area, it is critical to be thorough when servicing the engine performance system. When the injectors are tested and cleaned or replaced, and the computer input sensors are checked or replaced, this goes a long way toward ensuring that the vehicle will have a fighting chance of passing our enhanced emissions test. Even if you don’t have mandatory emissions testing in your area, what kind of engine performance improvement will your customer realize when you pay close attention to those critical Powertrain Control Module inputs?Heck, let’s take it a step further and make certain that the mass airflow sensor is cleaned during our engine swap.During the test drive, all gauges are monitored for function and accuracy, the cruise control is tested and all vehicle systems are run through their paces. Back at the bay, the engine is checked for leaks, all clamps are snugged and another LOF is performed to remove break-in debris.The other test that is performed is a computer scan. Each computer-accessible engine is scanned for trouble codes and, if it has data stream, has each parameter scrutinized. Havana has purchased every Simu-Tech cable available (I’m not kidding). These guys take computer access seriously, as they should. Scrutinizing PCM data stream, especially when the cause of the engine’s demise is not apparent, is critical.If poor performance during the test drive is thought to be attributed to a restricted exhaust, the pipe is tapped ahead of the catalytic converter, and an exhaust backpressure test is performed. The tap is methodically moved toward the rear of the car until the restriction is located. All converters are also given the “tap test” to determine if the substrate has broken apart, or if loose chunks could be blocking the muffler.

Doing It Right The First Time
The day of simply replacing an engine and related parts by the seat-of-our-pants is gone. We all need to follow a comprehensive routine while estimating the job, and while performing the Pre-Delivery Inspection.

An engine replacement is full of surprises, and we need to minimize becoming blind-sided by unforeseen issues. If we develop and implement a process similar to the one used by Havana Machine, we can only increase parts sales and reduce comebacks.

10 Steps to a Quality Engine Installation
1. Intake Manifold: The intake manifold should be thoroughly cleaned. Remove baffle (where applicable) so that all collected contaminants can be eliminated. Check for cracks under the carburetor. All EGR passages must be cleaned and free of obstruction.2. Radiator: Replace core or rod and boil to remove corrosion and obstructions that will inhibit proper coolant flow. Always replace cap and thermostat. Oil coolers inside the radiator must be replaced while oil coolers external to the radiator must be thoroughly flushed to remove potential contaminants.3. Harmonic Balancer: Replace balancers set in rubber. The interior rubber deteriorates with age, allowing the balancer to slip, possibly causing timing problems and detonation, overheating, vibration and unexplained noises. Check key slot for excessive wear.4. Exhaust System: Check catalytic converters and exhaust systems for restrictions and leaks in front of O2 sensor. Inspect exhaust manifold control valve (butterfly) and heat riser.5. Ignition System: Replace distributor, wiring, coil and spark plugs to avoid poor performance. Check all integrated circuitry for function (MAP, EGR, O2 sensors, etc.) if equipped for electronic ignition. Check distributor advances.6. PCV Valve: Replace PCV valve and grommet and clean line. A plugged or faulty valve may cause excessive oil consumption and blowby. Check metal connections at carburetor for cracks. Inspect rocker cover baffle for possible restrictions.7. Fuel System: Carefully service or replace all aspects of the fuel system, i.e., pump, lines and carburetor or fuel injection components. Fuel lines should be checked for breaks or crimps. To avoid vapor lock, do not use copper replacement lines. 8. Accessories: Be sure to service accessories such as the alternator, starter, water pump, air compressor, fuel system, EGR valve and sensors to avoid premature failure.9. Rubber Goods: Replace small parts such as belts, hoses and motor mounts which become weak and worn with age.10. Filters: Replace filters (air, oil, fuel and crankcase) at the time of installation and service intervals. A flywheel bolt that protrudes into the crankcase should be used with a sealer to prevent rear oil leaks. (Do not use silicone unless it’s O2 sensor approved.)Courtesy Jasper Engines and Transmissions

Auto/Car Engine Water Pump-Automobile Overheating&Circulation Issues&Problems-Houston,Tx

Wednesday, November 21st, 2007

Water Pumps: Why They Fail And When To
Replace Them
By Gary Goms
If you’ve wondered how much work a water pump must do, remember that only about 30% of the heat energy produced by combustion results in mechanical energy. That estimate, of course, is a mathematical comparison between the heat value of the gasoline going into the engine, and the heat value of the mechanical energy coming out of the engine. The remainder of combustion heat must then be dissipated into the atmosphere through the exhaust, lubrication and cooling systems.Water pump operation is important because, if the coolant’s circulation rate is too slow, the coolant will begin to boil in the engine’s water jackets. Unfortunately, when coolant boils, it becomes gaseous and can no longer cool hot cylinder walls and cylinder heads. The result is overheating, which is a primary cause of catastrophic engine failure.To prevent the coolant from overheating, a water pump is used to circulate the coolant through the engine’s cylinder block, heads and radiator. As it circulates, the coolant absorbs heat from the engine block and dissipates it into the atmosphere through the radiator.Of course, coolant temperatures may vary according to ambient temperature, engine load and engine speed. Most modern engines must operate between 185° and 195° F coolant temperature to evaporate volatile combustion by-products from the lubricating oil, achieve correct dimensional fits between aluminum pistons and cast-iron cylinder walls, and to achieve optimum fuel vaporization in the cylinder head ports. To maintain a constant coolant temperature, a thermostat is usually placed at the coolant outlet on the engine assembly where it controls coolant flow into the radiator.Water Pump Design
Although the modern water pump may appear simple in design, the actual coolant circulating capacity of the pump is based on mathematical models that take into account the amount of heat generated by the engine under various driving conditions. Severe operating conditions, for example, may range from stop-and-go driving on a hot day to pulling a camping trailer over a high mountain pass on summer vacation.
Water pump components include the pump housing, impeller, seal, bearing, pump shaft and drive pulley hub. The water pump housing also incorporates one or more vent holes located between the bearing and seal to protect the bearing from coolant contamination if the seal begins leaking coolant. The impeller is designed to circulate coolant by using centrifugal force to impart motion to the coolant. Impellers are designed for either clockwise or counter-clockwise rotation so, for all practical purposes, an impeller driven in opposite rotation becomes a very inefficient coolant pump. In addition, an impeller must fit the water pump housing and engine block cavity perfectly to achieve optimum efficiency.In the modern vehicle, water pumps are designed to consume as little engine torque as possible while achieving the greatest possible coolant circulation. Consequently, the water pump is a compromise between circulating too little coolant at engine idle and too much coolant at maximum engine speed. Too little coolant circulation obviously causes overheating, while too much circulation wastes gasoline and aggravates water jacket erosion. Most passenger car water pumps may be designed to deliver approximately 10-gallons-per-minute flow at normal engine speeds. Here again, the flow depends largely upon the engine’s size and average load. Many manufacturers also boost water pump performance by installing molded plastic impellers, which may operate more efficiently than stamped alloy steel versions.Failure Profiles
Leaking shaft seals, which are the most common water pump failure, usually reveal themselves by leaving a coolant stain around the vent area. Shaft seal leaks can be difficult to diagnose because they can be intermittently temperature and pressure sensitive, and can be aggravated by rust and other particulate contamination in the system.
Shaft seal leaks can often be diagnosed by using a cooling system pressure tester to pressurize the cooling system. In most cases, however, a visual inspection is the most reliable method simply because most intermittent shaft seal leaks are detectable only by the traces of coolant around the vent area and surrounding parts.Noisy shaft bearings are usually the second-most common water pump failure. Most shaft bearings fail due to normal wear in the bearing or due to the normal oxidation of lubricant on the bearing surfaces. In rare cases, bearing failure can be hastened by over-tightening conventional accessory drive belts. In many cases, a water pump bearing also fails because it supports an unbalanced fan assembly that also may have bent or misaligned blades. Water pump bearings also can fail because an amateur mechanic diluted the lubricant by washing the pump in a solvent tank! The third and most rare water pump failure is the impeller slipping on the water pump shaft. Since the impeller and shaft is a press-fit assembly, slippage occurs most frequently on remanufactured water pumps. In other cases where a plastic impeller is used, the plastic material can degrade through sustained heat and age. In any case, slippage can be intermittent in nature and can depend greatly upon the temperature and speed of the engine. Last, some replacement impellers can be manufactured from inferior metals that are susceptible to rust corrosion. In most of these cases, impeller blades begin to break away from the impeller due to a rust-through condition, which results in decreasing pumping capacity and an increasing presence of rust contamination in the cooling system.When to Replace
Water pumps have become an important routine replacement item largely because the water pump may act to help tension timing belts or because it may be accessible only after the timing belts are removed. Since a water pump replacement essentially requires the same labor operations as a timing belt replacement, it’s more cost-effective to invest in a new water pump when timing belts are replaced. Because the service life of most water pumps averages between 100,000 and 150,000 miles, it’s good to recommend replacing any pump in that mileage range, especially if it’s part of a repair or new engine installation service.
Installation Precautions
Since most water pump failures are caused by leaking seals, it’s important to inspect the cooling system for the presence of abrasive rust or sand particles. Rust, in particular, will cause early seal failure because of its abrasive qualities. Although rust is difficult to remove, it should be flushed from the system as thoroughly as possible before the old water pump is removed. Adequate flushing is aided by removal of the thermostat, which allows for a maximum water pump circulation rate.
In rare cases, the presence of dirt or loose core sand left over from casting the engine block also may cause repeated seal failure on water pump replacements, especially if the vehicle is driven on extended trips. Last, but not least, remember that many vehicles require application-specific antifreeze to prevent corrosion in the cooling system and prevent premature water pump seal wear.Before installing a new water pump, always compare the fan or belt pulley flange height with that of the old pump. If the height isn’t to specification, belt alignment may be adversely affected. To ensure the pump has the correct rotation, compare the impeller for similarity of configuration and size. Also, make sure that the old gasket has been completely removed from the engine block in order to maintain correct tolerances between the pump impeller and engine block mount and, of course, to prevent leaks. Before bolting the pump to the block, test for insufficient block clearance by holding the pump against the block and turning the impeller. When all dimensions and clearances have been checked, the water pump is ready for installation.To prevent damaging the new water pump seal, make sure that the engine is completely filled with new coolant before starting the engine. With that done, always warm the engine until coolant circulates freely through the radiator and all air is bled from the system. Last, inspect for leaks and check the coolant level before releasing the vehicle to your customer.Want to be sure the water pump you installed doesn’t return as a comeback? Follow these helpful tips for a successful water pump installation.Make sure the mounting surface is clean, smooth and dry, and that there is no old gasket or sealer residue, no deep nicks or scratches, and no dirt, oil or grease on the surface.If there’s a gasket between the pump and engine, coat both sides of the gasket with sealer. If an anaerobic sealer or RTV silicone is used instead of a gasket, the sealer must be applied all the way around the bolt holes. Use only a 1/8² bead of RTV and allow it to set before installing the pump. Excessive RTV or uncured RTV can be drawn into the pump housing and cause premature seal failure.Water pump bolt threads that extend into the water jacket also must be coated with sealer to prevent leaks.Tighten the pump drive belt to specifications. Too much tension is hard on the belt and the pump bearings.If the radiator has a fan shroud, don’t leave it off. The shroud is there to improve the cooling efficiency of the fan. The fan also should be inspected and replaced if any of the blades are bent, cracked or damaged.If the radiator has an electric cooling fan, the operation of the fan should be checked to make sure it comes on when the engine reaches its maximum operating temperature. An inoperative fan can allow the engine to overheat in slow moving traffic or when running the air conditioning.

Engine / Automobile Timing Chain / Engine Timing Belt – Houston,Texas

Tuesday, November 20th, 2007

<><><><>Timing Chains & Gears


By Larry Carley, Technical Editor
lcarley@babcox.comEver wonder why some engines have a timing belt while others have a timing chain?As a rule, most pushrod engines use a timing chain to drive the camshaft, though some older four and six cylinder engines use a gear set. A short chain or gear set works well in this kind of application because the camshaft is located in the block just above the crankshaft. In overhead cam (OHC) engines, the camshaft is located high in the cylinder head far from the crankshaft. This requires a much longer chain or a rubber belt to drive the camshaft. In some engines, such as a Chevy 3.4L DOHC V6, a timing chain is used to drive an intermediate sprocket that drives two belts (one for each cam).Timing belts and chains carry a heavy load. They have to turn the cam with enough force to overcome the resistance of all the valve springs. Belts are made of synthetic rubber reinforced with tough fiber cords that provide tensile strength and prevent the belt from stretching. Chains are made of steel links connected by flexible rollers. Chains are more durable than belts and typically have a longer service life. But chains are also heavier, noisier and more costly to replace. That’s why belts are used on many OHC engines.

The main cause of belt wear is heat. As a belt wraps around and turns the sprockets, friction creates heat (this is in addition to the heat from the engine itself). Over time, this causes the rubber to lose flexibility, harden and crack. The cords inside the belt also weaken as the belt accumulates wear, increasing the risk of the belt breaking.

Timing chains, by comparison, are mostly immune to the effects of heat. But they do stretch as they age. The increase in length can have an adverse effect on camshaft timing and become a source of noise if the chain becomes loose enough to rub against the inside of the timing cover.

When The Cam Drive Fails
If a timing belt or chain breaks, or the cam drive gears fail, the cam stops turning, the engine loses all compression and the engine stops running. A cam drive failure can also cause expensive valve damage in “interference” engines that don’t have enough clearance to prevent the valves from hitting the pistons if the cam stops turning or jumps out of time.

Interference engines include most Acura, Honda, Hyundai, Infiniti, Isuzu, Nissan and Porsche engines, also some Audi, BMW, Mazda, Mitsubishi and VW engines, as well as Chevrolet 1.5L and 3.4L, 1995 and newer Chrysler 2.0L and 2.5L, 1997 and newer Chrysler 3.2L and 3.5L, and Ford Probe 2.0L and 2.2L engines. Timing chains or belts may also jump time if loose. The engine may continue to run but will experience a loss of performance because of the altered valve timing.

Belt and Chain Replacement
The best time for a vehicle owner to replace a timing belt or chain is before it fails. For older (typically mid-1990s and back) engines, the recommended replacement interval for timing belts is usually 60,000 miles. On newer engines, the original equipment belts are made of better materials and usually have a service life of 100,000 miles or more.

If an engine is being rebuilt, the timing belt, chain or cam gears should always be replaced. Don’t take a chance reusing an old timing belt, chain or gear set. A high mileage timing chain that has stretched and is loose can’t maintain accurate valve timing and should be replaced if play exceeds specifications. The camshaft and crankshaft sprockets should also be replaced along with chain. These parts are included in a typical three-piece timing set.

On OHC engines that use a timing chain, the timing set may also include a chain damper or tensioner. The chain damper, tensioner, guide or rails should also be replaced when the chain and sprockets are replaced because these components play a vital role in supporting the chain and keeping it tight.

A case in point is grinding noise coming from the timing chain cover area in 2000 to 2003 Ford Crown Victoria and Mercury Grand Marquis with the 4.6L V8. According to Ford Technical Service Bulletin 03-15-7, excessive wear in the timing chain tensioner arms can cause a noisy condition. The tension arm has an aluminum base with a nylon surface. So if you find nylon and/or aluminum particles in the engine oil it probably means the tensioner, tensioner arms, timing chains and gear set all need to be replaced. The Ford part numbers for the 2000 model year tensioners are F6AZ-6L266-DA (RH) and F6AZ-6L266-CA (LH). For the 2001 to 2003 model years, the tensioner part numbers are 1L3Z-6L266-AA (RH) and XL1Z-6L266-AA (LH). The tension arms are 1L2Z-6L253-AA (RH) 1L2Z-6L253-AA (LH).

You should always check a database of technical service bulletins for any engine you are rebuilding to see if there are any known issues with the cam drive. Ford TSB 97-2-8, for example, describes a clattering noise at engine start-up, after the engine has sat overnight, that may be heard on 1995 Ford Contour and Mercury Mystique models with a DOHC 2.5L V6. Oil leaking out of the chain tensioners causes the timing chain to momentarily rub against the tensioner ratchet when the engine is first started. The noise only lasts a couple of seconds and goes away as soon as the engine builds up oil pressure.

The cure, says Ford, is to replace the original chain tensioner components with redesigned parts. These include two timing chain tensioners F5RZ-6L266-CA, the left hand tensioner adapter F5RZ-6C275-BA, the right hand tensioner adapter F5RZ-6C275-AA, the left hand chain tensioner arm F6RZ-6L253-AA and the right hand chain tensioner arm F6RZ-6L253-BA. The two DOHC timing chains and guide assemblies should also be replaced at the same time.

Replace, Don’t Reuse
As for timing belts, they do not stretch with age, but become weak internally and may fail with no warning. Consequently, a visual inspection of the belt may not reveal much. If the mileage is not known, replace the belt. And if the mileage is known and a belt has more than about 30,000 miles on it, replace it anyway.

Many OHC timing belt failures are actually caused by faulty belt tensioners and idler pulleys. Like belts, these parts also wear out and should be carefully inspected and replaced when the belt is changed. Reusing old tensioner components increases the risk of premature belt failure. The lifespan of many OEM tensioner components is only about 2,000 hours, or the equivalent of 40,000 to 60,000 miles or more depending on how the vehicle is driven. Tensioner bearings are “sealed for life” and are not serviceable, so there’s no way to clean, inspect or re-lubricate the bearings when a timing belt is changed. What’s more, it’s difficult to determine the true condition of the tensioner components because they are not running under a load. Consequently, a simple visual inspection may miss tensioner bearings that are on the verge of failure.

If you find a belt with stripped cogs, that tells you something in the cam drive system has jammed or stuck, overloading the belt and causing it to shear teeth or jump time. The most likely culprit is the camshaft, which may have seized due to engine overheating or lack of lubrication (low oil level or loss of oil pressure). Be sure to check the straightness of the cam bores in the cylinder head, and straighten or align bore the head as needed before the head goes back on the engine.

When OHC cylinder heads get too hot, they usually swell up in the middle causing the cam to bend or bind. In some cases, this may break the cam, snap the timing belt or shear the cam drive sprocket off the end of the cam.

Get The Right Parts
Similar engines may use different cam drive components, so make sure you get the correct replacement parts for the engine. For example, Chevy has used three different timing gears for the 262 V6 since it first appeared in 1985. The flat tappet engines use a p/n 340235 gear, the non-balancer, roller cam engines use a p/n 12552128 gear, and the balancer engines use a p/n 10144121 gear. None of these gears are interchangeable.

On 1992-’98 262 engines with balance shafts, make sure the two balance shafts are correctly phased with camshaft. The shafts are gear driven off the cam, and there are two different gear sets, one with wide teeth and one with narrow teeth. The wide teeth gears were used on the earlier engines, and can be replaced with the later narrow gears to reduce noise.

Chevy has also used two different timing gears on its LT1 V8 engines. The earlier 1992-’95 LT1 engines with aluminum heads use a p/n 10128349 cam drive gear with a small hole with 16 splines in the center. On 1995 and later LT1s, a different gear (p/n 10206039) with a larger, unsplined center hole is used.

You’ll also find three different front covers on these engines. The 1992-’94 engines have a cover with two small holes for the water pump and distributor drives, and a large hole for the crank. The 1994-’95 engines have a large center hole for the distributor, and the 1996-’97 covers have an extra hole at the bottom for the crank position sensor.

It’s also a good idea to inspect the seal surface on the water pump drive shaft when changing the timing gears and chain on an LT1. The water pump is driven off the cam on this engine, and if the shaft is worn it will leak.

If you are replacing a timing chain on a late model overhead cam engine with variable valve timing (VVT), be sure to look up the assembly procedure so the VVT unit on the end of the cam is installed correctly. On GM’s Vortec 4200 DOHC inline six (introduced in 2002 on the Chevy TrailBlazer, GMC Envoy and Oldsmobile Bravada), the VVT “phaser” unit is mounted on the end of the exhaust camshaft and uses oil pressure to change exhaust valve timing up to 25 degrees. The VVT unit is controlled electronically by the powertrain control module via a solenoid valve that opens to route oil pressure to the unit. When replacing the timing chain on one of these engines, you have to make sure the VVT unit is in the correct position (fully advanced).

Timing Belt Installation Tips
Make sure the replacement timing belt is identical to the original. Belt length, width, tooth profile and pitch must all be the same, and the material must be the same or better. Do not substitute a less expensive neoprene belt for one made of HSN (Highly Saturated Nitrile). Use a quality brand of belt because some no-name brands use inferior materials that won’t last as long as the OEM belt or a quality aftermarket belt.

When changing a belt, never attempt to “stretch” a belt over a pulley. Belts, remember, do not stretch and forcing one to do so will likely damage the cords and cause it to fail.

Also, never pound on a sprocket to force it into place. If it isn’t sliding into place, check its alignment and fit.

Misalignment problems in the cam drive can also occur if the cam sprocket is installed backwards, the wrong thickness of washer is used (incorrect end play), a thrust button is forgotten, or the crank sprocket is not positioned properly on its keyway.

Belt tension is critical to belt longevity. Adjust to the recommended specifications (always refer to the manual because the amount of recommended play can vary depending on the application). If the belt is too tight, it won’t last. If the belt too loose, it may jump time.

On a Chrysler 2.0L engine, for example, here’s the recommended procedure for adjusting the belt:

1. Loosen the tensioner pulley bolt.

2. Using tool MD998752 and a torque wrench, turn pulley clockwise with 22-24 in.lbs., hold the pulley and torque the tensioner bolt to 31-40 ft.lbs.

3. Remove rubber plug from engine mount bracket and screw in tool MD998738 until it moves the automatic tensioner pushrod in.

4. Remove the 0.055″ rod from the tensioner body.

5. Remove tool MD998738, turn crankshaft clockwise two revolutions and wait 15 minutes.

6. Measure pushrod protrusion. It should be .15″ to .18″.

7. If not, repeat tensioning procedure.

Some engines such as GM’s 3.4L DOHC V6, a hydraulic tensioner is used to keep the belt tight. On these engines, the tensioner must be prepared before it is reinstalled by draining out the oil, fully retracting the plunger and refilling it with 5W-30 motor oil.

Also, check for revised or updated belt adjustment procedures that may be more recent. An example here is the timing belt and tensioner setup procedure that Ford originally published for the 1998-2000 Contour, Escort ZX2, 2000 Focus, 1998-2000 Mercury Mystique and 1999-2000 Mercury Cougar with 2.0L engine. Ford TSB 99-25-4 provides the following corrected information:

To achieve proper timing belt tension on this engine, Ford says the camshaft sprocket bolts should be loosened enough to permit the sprockets to turn freely on the camshafts. Once this has been done, rotate the crankshaft clockwise so cylinder #1 is at top dead center. Then install the camshaft alignment tool in the camshaft slots to hold the cams in place.

1. Back out the tensioner bolt four full turns and position the tensioner so the locating tab is at approximately the 4 o’clock position. Line up the hex key slot in the tensioner adjusting washer with the pointer that is located behind the pulley.

2. Working counterclockwise from the crank sprocket, install the timing belt.

3. Rotate the tensioner locating tab counterclockwise and insert the locating tab into the slot in the rear timing cover.

4. Position the hex key slot in the tensioner adjusting washer to the 4 o’clock position.

5. Tighten the attaching bolt enough to seat the tensioner firmly against the rear timing cover, but still allow the tensioner adjusting washer to be rotated using a 6 mm hex key.

6. Using the hex key, rotate the adjusting washer counterclockwise until the notch in the pointer is centered over the index line on the locating tab. (The pointer will move in a clockwise direction during adjustment).

7. While holding the adjusting washer in position, torque the attaching bolt to 18 ft.lbs. (25 N.m).

NOTE: If the pointer does not remain centered over the index line during final tightening, loosen the bolt and repeat the procedure beginning with step 4.

Special Timing Chain and Belt Tools
Before you replace a timing belt, chain or gear set on some engines, you will have to look up the timing reference marks. Some engines have multiple timing marks that can cause confusion if you don’t know which ones to use or how to line them up.

Many engines also require special tools when changing a timing belt or chain. At the very least, you should have a belt tension gauge to make sure the tension on a timing belt is correct. Special camshaft positioning tools (or a bolt or pins) may also be required on some dual overhead cam engines to hold the cams in place while the belt or chain is replaced.

Here are just a few of the special OEM timing tools that may be required:

· Audi 2.8L V6 (1992-’94) – Requires camshaft holding tool 3243, and crankshaft holding tool 3242.

· Chevrolet 3.4L V6 DOHC (1991-’94) – Requires two camshaft timing clamps J38613-A.

· Chrysler 2.0L OHC – Requires tensioner tool MD998752 and tensioner adjuster tool MD998738. The tensioner adjuster tool threads into a hole under a rubber plug in the engine mount bracket.

· Chrysler/Dodge/Plymouth 2.2L & 2.5L (1981-’95) – Requires tensioner wrench C-4703.

· Ford Escort 1.9L (1985-’91) – Requires crankshaft pulley wrench D85L-6000-A and camshaft holding tool D81P-6256-A.

· Ford Taurus SHO 3.2L V6 DOHC (1992-’94) – Requires tensioner tool T93P-6254-B and torque wrench adapter T93P-6254-A.

· Honda Accord 2.2L (1990-’94), Prelude 2.2L V-TEC (1993-’96) and 2.3L (1992-’94) – Requires the following for balancer shaft belt installation: locating pin 07LAG-PT20100 (or a M6×100 mm bolt).

· Honda Prelude 2.0L & 2.1L (1988-’91) – Requires two 5mm pin punches to hold dual overhead cams at TDC.

· Hyundai Sonata 2.0L & Elantra 1.8L & 1.6L – Requires tensioner pulley socket wrench 09244-28100 and tensioner adjusting screw 09244-28000.

· Isuzu 1.5L (1985-’93) – Requires belt tension gauge J326468-B and crankshaft wrench J37376.

· Lexus ES250 2.5L – Requires crank pulley holding tool 09213-70010, pulley tool handle 09330-00021, and puller 09213-60017.

· Lexus SC400 & LS400 4.0L V8 – Requires crank pulley holding tool 09213-70010, pulley tool handle 09330-00021, and puller 09213-31021.

· Mazda pickup 2.3L – Requires tensioner adjusting tool 49-UN10-067.

· Mitsubishi 3.0L V6 DOHC Diamante & 3000GT (1993-’95) – Requires tensioner tool MD998752-01.

· Mitsubishi 2.4L Eclipse & Montero 3.5L V6 DOHC – Requires tensioner tool MD998767.

· Mitsubishi 2.0L Eclipse & Galant (1988-’94) – Requires tensioner pulley tool MD998752 and tensioner tool MD998738.

· Nissan 3.0L V6 (300ZX) – Requires tensioner tool EG 14860000.

· Toyota 3.4L (4Runner) and RAV4 2.0L – Requires crank pulley puller 09950-50010.

· Toyota 3.0L V6 4Runner (1993-95) and Camry (1993-96) – Requires crank pulley puller 09213-31021.

· Volkswagen 2.0L Golf, Jetta & Passat (1990-94) – Requires tension gauge VAG 210 and 2-pin wrench – Matra 159.

Engine / Car Evaporative Emmissions Diagnostics & Problems – Engine Codes: p0440,p0441,p0446,p0450,p0451- Houston,Tx

Tuesday, November 20th, 2007

Foreign Affairs


A Recipe for Locating EVAP LeaksBy Pete Meier, contributing writerWhen I first had to diagnose a Toyota EVAP code, I found the available information a little lacking. So I decided to do a little homework … and the following article is the result of what I’ve learned. I hope it makes diagnosing and repairing these systems a little easier for you.First, a word on basic EVAP leak testing. I often see techs trying to find EVAP leaks by immediately using the smoke function on an EVAP tester. Personally, I prefer to first verify there is a leak, then treat it in the same way I would if I were looking for an open wire in an electrical system.Seal It Up
The first step is to seal the system for testing. This is usually accomplished by sealing the air vent line to the tank and any other normally open vent lines in the system. One trick I’ve learned is to first hook up to the PCM and enter via Global OBD II. Then I go to Mode $08-Request Control of Onboard Systems (see Photo 1). Currently, the only option listed here is the EVAP system, and by commanding control, you order the PCM to close the system for testing. If this option is available, you don’t have to do anything to seal the system; the PCM will do it for you. Then all that’s left is to connect to the service port and pressurize the system. (Note: On some makes, you may still have to seal the tank air vent.) You will have to cycle the key in order to return the EVAP system to its normal state.Once the system is sealed, I use the pressure function of the tester to pressurize the system. I want the indicator ball to fall all the way to the bottom. Depending on the amount of fuel in the tank, it may take a minute or two. If the indicator won’t go down all the way, then I know there is a leak. My last step in checking the system is to release the pressure switch on the tester while it’s still connected and wait about 30 seconds. Then I reapply pressure. If the ball jumps up and starts back down, I know I have a really small leak — typically weathered rubber lines or seals.If a leak is indicated, the first thing I do is check the cap (don’t do this before testing or you won’t be able to verify you’ve found and fixed the problem). Even though the cap appears to be tight, that doesn’t mean it isn’t leaking. I like to remove the cap and seal the opening with one of the plugs supplied with the tester. If my leak test passes, I reinstall the cap and test once more. If it passes again, then I know the cap was just left loose and I’m done. If it fails, I inspect the cap and fuel neck for damage and repair as needed. Don’t forget to verify the repair. If the leak is not in the cap, then I break the system down into two parts, the purge side and the tank side. I isolate the two parts at the canister, and test each individually. Once I find which leg the leak is in, I can either break it down into smaller sections, or go straight to the smoke and look for the cause.If the leak is in neither side, then it’s time to test the canister itself. Some canister designs are simple, and others, like Toyota’s, are a little more complex. Here I refer to the service information for detailed testing instructions.Once the leak is repaired, I again pressure-test the entire system to verify the repair. This is an important step in customer satisfaction. Many EVAP codes are “2 trip” codes, meaning that the conditions that are needed to set the code must occur on two consecutive monitors in order for the MIL to be illuminated. This can take several drive cycles to accomplish and make many EVAP repairs hard to verify by running the monitors alone. And the average customer doesn’t understand or care; they only know the light is back on and they are back in your shop for the same thing. Toyota/Lexus System Types
There are two types of EVAP systems in use on Toyota and Lexus vehicles. The first is referred to as the “early” or “non-intrusive” type, and the second is referred to as the “late” or “intrusive” type. The PCM strategies for leak detection and system monitoring are different between the two and affect diagnostic procedures and code definitions.
The early system was developed to meet initial EPA and CARB requirements for leak detection. The late-type system was implemented when leak detection standards became more stringent. The easiest way to ID which system is in use on the vehicle you’re testing is to look for the fresh air line connected to the intake boot or air box. If this line is connected directly, it’s an early system. If it’s routed through a solenoid, it’s a late system (see Photo 2). By the way, the solenoid in the late system is called the Canister Closed Valve or CCV for short.Another important difference between the systems is located on or near the canister itself. On both systems, the PCM uses information from the Vapor Pressure Sensor (VPS) to monitor for leaks. The important difference is in how this information is obtained.On the early system, a solenoid called the 3-Way Vacuum Switching Valve (VSV) is used to connect the VPS to either the canister side of the system or the tank side of the system. The PCM then compares pressure in the side being tested to its internal expectations. If these are not met, a leak code is set. We’ll be discussing that in more detail in a moment.In the late system, the 3-Way VSV is replaced by a Bypass Vacuum Switching Valve. This valve connects the tank and canister side together for leak testing. The PCM closes the CCV mentioned earlier and opens the Bypass VSV, then commands the purge valve (called the EVAP VSV) on and draws a vacuum on the entire system until a specified pressure is met. It then closes the EVAP VSV and monitors the rate of vacuum loss to an expected value. Anything outside of this value will trigger a leak code.It’s also important to note that EVAP codes are “2 trip” codes and monitors can take 20-30 minutes or longer to complete under very specific conditions. This makes verification of repairs in the bay more important, as test driving to run the monitors is impractical. Also, be aware while reviewing this information that restrictions in the system can also cause codes to be set as quickly as leaks can. Lastly, always diagnose and repair leak codes first before diagnosing component failures.
Early System Codes, Conditions and Diagnostic TipsP0440 — EVAP System Malfunction
This code is set when the 3-Way VSV is switched to the tank side of the system, and the PCM sees atmospheric pressure instead of the values expected. This code is always a leak on the tank side of the system.
P0441 — Vapor Purge Flow Detection
This code can be set by two different conditions — either by a restriction in flow during purge or by purge occurring when it shouldn’t. It may also be caused by a leak in the purge side of the system. The PCM looks for these three conditions:

  1. If the expected pressure drop in the canister is not seen by the PCM when the EVAP VSV is commanded open, the PCM suspects a restriction in the system.
  2. If the PCM sees a pressure drop in the canister on initial start-up, the PCM suspects the EVAP VSV is not closed when it’s supposed to be.
  3. If the PCM doesn’t see pulsations in pressure in the canister during normal purge, the PCM suspects a fault in the purge system.

If this code is set alone, check for leaks in the purge line and check the operation of the EVAP VSV. To check for restrictions in the purge system, disconnect the purge line from the canister and connect it to a vacuum gauge. With the engine running, command the EVAP VSV on — vacuum should equal manifold vacuum (see Photo 3). Then command the EVAP VSV closed — vacuum should be 0. If not, test the EVAP VSV and its related electrical wiring for proper operation.This code test is dependent on readings from the VPS which, in turn, depends on proper operation of the 3-Way VSV. Should a problem exist in these components, expect a possible code P0446 to also be set (see below). And, as with any diagnostic, do a visual inspection of the lines for proper connection and condition.P0446 — 3-Way VSV Fault
The PCM tests the operation of the 3-Way VSV by first looking for a pressure difference when it’s switched from the tank side to the canister side. Remember, the 3-Way VSV switches the input to the VPS (see Photo 4). If no difference is seen, two steps are taken:

  1. If pressure pulsations (caused by normal pulsations in manifold vacuum) during purge are not seen by the VPS, the PCM concludes the 3-Way VSV did not switch.And/Or……
  2. If pressure pulsations are detected in the tank side of the system, then the PCM judges that the 3-Way VSV did not switch.It’s important to note that leaks in the system can affect these code criteria, and will also likely set either a P0440 or P0441. If so, diagnose and repair the leak conditions first before verifying operation of the 3-Way VSV. It’s also possible for an internal canister failure to set this code. If all other causes are ruled out, or freeze-frame data shows that the code set at 0 mph, suspect a canister fault and see the model-specific service information for canister testing procedures.

3-Way VSV failure is common, but placement of these valves can make bench testing difficult and time consuming. Another factor in diagnosing this code is the sensitivity of the VPS itself and the slow “refresh” rates of most scan tools. Here are some ideas on testing the valve without removal, and using a lab scope or DSO.Using the appropriate wiring diagram, locate the signal wire from the VPS to the PCM. In some cases, connecting directly at the PCM is the easiest. On others, it may be more practical to connect in the harness or at the VPS itself. Connect the DSO to this signal, command the 3-Way VSV “on” with a scan tool, open the tank cap and note the reading. That’s atmospheric pressure, and what we don’t want to see during our testing.Now reinstall the cap and let’s monitor the voltage. Connect the purge line from the canister directly to intake vacuum, either by commanding the EVAP VSV open, or using a length of vacuum line, and look for the pressure drop on the VPS signal line. You may also see the pulsations that should be present (see Photo 5). When the 3-Way VSV is “off” it’s connected to the canister side of the system, so make sure you command the VSV to this position.Now, command the 3-Way VSV “on.” It should switch to the tank side of the system, and you should see a corresponding change in the VPS signal. The VPS voltage will increase with pressure increase and decrease with pressure loss.If the results are reversed from what’s expected, check the hose routing between the 3-Way VSV and the VPS. If results on both sides are the same, check the electrical and mechanical operation of the 3-Way VSV and condition of the connecting lines. Inspect the valve for debris clogging the passages. If any is noted, then suspect internal failure of the canister as the root cause (charcoal granules escaping from the canister and clogging the valve).

P0450 or P0451 — Vapor Pressure Sensor Fault
Both of these codes relate directly to the VPS. They are set when the signal from the VPS is outside of specific parameters internal to the PCM. Use the DSO or scan PID to verify the signal fault and use basic electrical diagnostics to isolate the cause — typically a faulty sensor, open wiring or poor ground. Of course, verify that hose routing to the VPS and 3-Way VSV is correct. Check freeze-frame data as well; a run time of less than 200 seconds is a good indication of a fault in the sensor itself.
Late System Codes, Conditions and Diagnostic Tips
Remember the differences in the late system? The PCM uses a Bypass VSV and a Canister Closed Valve to seal the system for leak detection monitoring. The VPS is now mounted on the fuel tank and there is no 3-Way VSV. The PCM checks the system by closing the CCV and opening the Bypass VSV. It then opens the EVAP VSV and pulls a vacuum on the entire system until a specified pressure is met. It then closes the EVAP VSV and monitors the rate of vacuum decay in the system. Some decay is normal as tank pressure rises from fuel evaporation. Anything outside of the “normal” rate can trigger a code.
(Note: Some 2003 and later models have repositioned EVAP components to areas that make access more difficult. For these systems, the manufacturer has outlined a six-step test using the factory scan tool to assist in diagnosis.)P0441 — Purge (EVAP) VSV Operation
To test the EVAP VSV, the PCM seals the system as described earlier. If the specified pressure drop is not reached, or the pressure drop continues past the point that the PCM commanded the valve closed, this code will be set.
To diagnose this code, first make sure no leak codes (P0440 or P0442) are set. Any leaks in the system will not allow pressure to drop and can also set this code. If no other codes are set, you can monitor the VPS signal with either a scan tool PID or a DSO on the signal wire. Command the EVAP VSV to open and look for the pressure drop on the VPS signal. If no drop is seen, check the operation of the EVAP VSV itself and check the lines for restriction.If pressure drop is normal, then command the EVAP VSV closed and look for continuing vacuum on the purge line or as indicated by the VPS signal. If continued drop is noted, test the mechanical condition of the EVAP VSV.P0440 — EVAP System, Large Leak Detected & P0442 — EVAP System, Small Leak Detected
As described earlier, the PCM seals the system and applies a small vacuum. It then monitors vacuum decay. A rapid rate of decay indicates a large leak, and a rate of decay just above normal indicates a small leak. Use an EVAP tester as described in the beginning of this text to isolate the leak.
One important note: When testing Toyota/Lexus late systems for leaks via the service port, you will not be testing the fresh air inlet to the intake or the CCV valve. This line and valve need to be tested separately. The CCV is a common fault item, and some models have a TSB on an updated design.P0446 — Vent Control-Canister Closed Valve & Bypass Valve Operation
This is a two-stage test of the system’s ability to be sealed for testing. It shares nothing in common with the early system code P0446. In the first part of the test, the PCM opens the CCV and monitors the pressure increase in the system via the VPS. No change or a change at a rate less than the expected values is read by the PCM as a restriction on the fresh air inlet side of the system. This is a test for restrictions in the air inlet line. A leak in this line will set a corresponding leak DTC as described earlier.
In the second part of the test, the Bypass VSV is closed, isolating the tank from the rest of the system (and the open CCV). The pressure increase rate should drop as a result. If no change is seen, the PCM concludes that the Bypass VSV did not close.Testing is fairly simple. To test the CCV, command the valve open and ensure that there is free flow through the line all the way to the canister connection. Closing the valve should result in no flow (see Photo 6). Again, the CCV is a common fault item, so start here.To test the Bypass VSV, disconnect the canister side line to the valve and monitor VPS signal while applying vacuum or low pressure from the EVAP tester to the line with the valve commanded open. The VPS should read the change. With the valve commanded closed, no change should be seen.If either valve fails these tests, proceed with normal electrical-mechanical tests of the valves themselves. You should be able to hear them “click” when commanded on and off.And, as always, once your repair is made, verify the repair and system function before returning to the customer.Well, there you have it. Now you know what I know about diagnosing and repairing Toyota/Lexus EVAP systems. I’m sure we could both stand to learn more, but I think you’ll find this information will make it easier and more productive for you the next time you find a Toyota/Lexus in your bay with an EVAP failure.

Tire Pressure Monitoring Systems Present a New Service Opportunity – Houston, TX

Monday, November 19th, 2007

By Larry Carley, Technical Editor
lcarley@babcox.comChanging technology always brings with it a need for new tools, and today’s new Tire Pressure Monitoring Systems (TPMS) are no exception. In 2000, Congress passed legislation called the TREAD (Transportation Recall Enhancement, Accountability and Documentation) Act in response to tire failures that were causing SUV rollovers. Many of these tire failures were blamed on underinflated tires. Studies have shown that nearly 250,000 accidents a year in the U.S. may be attributed to low tire pressure, and about 75% of all roadside flats are preceded by a slow leak or under inflation.Low tires also increase rolling resistance and increase fuel consumption. According to the U.S. Department of Transportation, low tires waste 5.4 million gallons of fuel a day! Fuel efficiency is reduced 1% for every 3 psi under-inflation, so keeping tires properly inflated translates to a free tank of gas every year.
The TREAD Act requires vehicle manufacturers to equip all passenger cars and light trucks under 10,000 lbs. with tire pressure monitoring systems starting with 20% of model year 2006 vehicles. The law requires 70% of all vehicles to have it by model year 2007, and every new vehicle to be equipped with TPMS by 2008.Actually, about 45% of 2006 vehicles have TPMS, and a number of earlier models dating as far back as 1997 (such as Corvettes with run-flat tires) have TPMS as well. So there are more than 20 million vehicles with TPMS on the road today.Service Opportunity
Adding TPMS to a vehicle adds yet another warning light. Like all the other onboard electronics, TPMS monitors itself and turns on a warning light if it detects a fault such as loss of signal from one of its tire pressure sensors.
There are two basic types of TPMS, direct and indirect. Direct systems have a pressure sensor in each tire. The sensor may be attached to the inside of the wheel or it may be located at the base of the valve stem. The sensor contains a pressure transducer, battery and transponder that broadcasts a signal periodically. Each sensor is individually coded so the TPMS module can keep track of the signals and identify any tire that is low.The signals sent by the pressure sensors may be received by the “keyless” entry system on some vehicles, the Powertrain Control Module or the TPMS module. The coded signal is broadcast at 125 kHz, or 315 or 434 MHz (depending on the application), and includes the sensor’s location and pressure reading. On most systems, the signal is broadcast every 30 to 60 seconds when the vehicle is traveling faster than 12 to 15 mph.If tire pressure drops below a certain threshold (the law says 25% less than the recommended inflation pressure, but some systems will alert the driver if the pressure drops only 15%), the system will warn the driver. On some vehicles, a low tire will turn on a “LOW/FLAT TIRE” warning lamp or U-shaped icon. On others, it may also display that actual pressure reading in psi or kpa.The main service issue with direct systems is loss of signal from any of the tire pressure sensors. This may happen if the transducer or transponder fails, or the battery goes dead. Most use a long-life lithium battery with a life expectancy of five years or more, but they don’t last forever. Consequently, once these vehicles get some age and miles on them, sensor failures will occur and repairs will be needed. Most OEMs are also recommending the TPMS pressure sensors be replaced when the tires are replaced. This requires a “relearning” procedure so the TPMS module can relearn the position of each sensor (right front, left front, right rear and left rear).With indirect TPMS systems, there are no pressure sensors in the wheels. Tire pressure is monitored by comparing the relative speeds of the wheels via the ABS wheel speed sensors. Loss of air pressure from a tire causes a decrease in its diameter, which can be detected as a slight change in speed. Indirect systems are not as sensitive as direct systems, but require no additional hardware in the wheels. It’s essentially an enhancement to the existing ABS system. Failures here will be limited to the wheel speed sensors, which will also affect the operation of the ABS/traction control/stability control system.TPMS Kits
Though TPMS is primarily an OEM-installed item, aftermarket TPMS kits are available for retrofitting older vehicles. The kits include pressure sensors for each wheel, a TPMS control module/receiver and a dash warning panel to alert the driver if tire pressure is low. Most of these kits cost several hundred dollars, but there are a few low cost kits that sell for under $100 that transmit a pressure reading to a special tire gauge.
TPMS service kits are another item that your shop will need in order to service vehicles with direct TPMS systems. The service kits include all the caps, cores, grommets and nuts that are needed to replace valve stem-mounted pressure sensors in the wheels.Tooling Up
Servicing TPMS systems will require a variety of special tools. For removing valve stem-mounted pressure sensors, various valve core and nut tools will be needed, including 11 and 12 mm sockets. The torque on the nut at the base of the valve stem is critical because too much torque may damage the sensor and too little torque may allow air leaks. For tightening the base nut, plan on using a valve torque tool (essentially a mini-torque wrench that reads 2 to 10 Nm).
For testing sensor transponders and running relearn procedures, you will need a special TPMS test and learn tool and/or scan tool. Dedicated TPMS testers are small hand-held products that communicate electronically with the sensors and TPMS system. The unit typically activates the pressure sensors so they will broadcast a signal. The unit then programs the TPMS module or receiver in the vehicle so it will recognize which sensor is which (RF, LF, RR and LR). The tool can also be used to verify the operation of each individual sensor and to troubleshoot TPMS faults. Many of these tools have a USB port that allows the tool’s software to be updated as needed, and to download information from the tool to a PC for printing or recording.TPMS test and learn tools are available from a variety of tool suppliers, and typically sell for $500 or less. Most of these tools will work with all types of pressure sensors, but some may be limited to specific models or types of sensors (such as sensors that operate in continuous mode or modulated mode only).For more advanced diagnostics involving communication problems between the TPMS module in the vehicle and the PCM or keyless entry system, an OEM scan tool or aftermarket professional grade scan tool with the appropriate software will be needed. A scan tool is also needed for most indirect (ABS) TPMS systems, too, for diagnostics and resetting the system.Service Precautions
On vehicles with direct TPMS with pressure sensors attached inside each wheel, the sensor is usually mounted in the drop center of the wheel 180 degrees (on the opposite side) from the valve stem. If you’re changing a tire on one of these applications, avoid dragging the tire bead across the sensor when dismounting or mounting the tire on the wheel as this may damage the sensor or tire bead.
On applications where the TPMS pressure sensor is on the end of the valve stem, the valve stem should be positioned 180 degrees from the bead breaker on the tire machine when dismounting the tire.An alternative method for changing tires on vehicles with valve stem-mounted sensors is to vent all the air from the tire (by removing the valve core), then remove the nut on the base of the valve stem and allow the sensor to fall inside the tire. The sensor can be retrieved from inside the tire after the bead has been broken loose.As with normal tire service procedures, new valve stem seals should be installed on the pressure sensor to assure a long-lasting, leak-free installation.Most direct TPMS systems require a relearn procedure if any of the sensors have been replaced, or if any of the tires have been rotated to a different location on the vehicle. The relearn procedure will vary from one vehicle to another, so always refer to the owner’s manual or service literature for the exact procedure that is required. Generally, one of two methods will be used: a magnetic tool that is placed over each valve stem in a specific sequence, or using a transponder and/or scan tool to reset the system.For example, on Corvette and Cadillac applications, the relative position of each tire pressure sensor can be relearned either way, by placing a J-41760 magnet over the valve stem, or by using a Tech 2 or equivalent scan tool to run the relearn procedure.Magnetic Method: With the key on, engine off, press both the lock and unlock buttons on the key fob. A horn chirp within 10 seconds indicates the TPMS receiver is in the programming mode. Place the magnet over the left front valve stem until the horn chirps once. This forces the LF pressure sensor to transmit its code to the main module. Repeat the same procedure for the right front, right rear and left rear sensors in this order.Note: You have only 60 seconds per wheel to complete this procedure otherwise the system will stop and you’ll have to start over. Verify all four pressure readings are displayed on the driver information center.Relearn procedure with a scan tool: Choose Tire Pressure Monitor from the menu (Body/Remote Function Actuation/Special Functions/Set Options/Tire Pressure Monitor) and follow the prompts for the relearn procedure. This mode will program a unique code into the TPMS receiver’s memory for each sensor location.Note: Do not attempt a relearn procedure if there is a similar vehicle with TPMS nearby. Signals from the other vehicle may interfere with the vehicle you are reprogramming.

Engine / Auto / Car Timing Chain / Timing Belt 22r series – Toyota’s Cars & Trucks (same design almost 30yrs. ) – Houston,Tx

Tuesday, November 13th, 2007

Servicing Solutions



Chain Reaction: Timing Chain Replacement on Toyota’s 22R Series Engine

By Larry Bailly

Toyota’s 22R series four-cylinder SOHC engine has survived and thrived in its cars and trucks for nearly 30 years, and is a desired powerplant for its power, torque and reliability. The basic design is a continuation of the engine that preceded it, the 20R, which was used in cars and trucks in the mid 1970s. Last month, we highlighted servicing head gasket issues on the 20/22R series 4-cyl SOHC engine. This month, we’ll take a look at timing chain and oil sludge issues for the 22R.A Series of Unfortunate Events
The incidence of timing chain failure on this series of engines seems to have increased over the last few years. We seldom saw a failure until 175,000 to 200,000 miles. Now, we often see failures under 150,000 miles. We’ve concluded that the use of lower viscosity oil has had a detrimental effect on timing chain life.Although there is still some disagreement on what is the ideal oil for all conditions, the fact remains that, on this engine, viscosity and oil pressure have a significant impact on timing chain life (more on this later).
There are, however, a couple of other problems that can significantly shorten chain life and cause other failures. Oil sludging, due to lack of maintenance and overheating, can damage any engine over time. Unfortunately, there is one other cause that is usually the direct result of an improper repair for a common oil leak.A common sequence of events in the failure of a timing chain on this engine often goes like this. The engine has a serious oil leak at the front pulley area. The leak is partially at the front crank seal, but the thin, odd shaped O-ring that seals the oil pump to the front cover is also leaking.The oil pump is removed, the seal is replaced (a repair sleeve is sometimes needed on the pulley), and everything is cleaned and reassembled. The engine starts, runs fine, oil pressure is normal and no warning lights are on. But, there is a light “ticking” noise from the front cover area. The noise doesn’t change significantly with engine speed, so the vehicle is returned to the customer, only to return in a short time with serious noises from the front cover and water in the oil — lots of water in the oil.So what happened?The top center retaining bolt for the oil pump housing was replaced with one of the other retaining bolts that is less than a quarter of an inch longer. That blew the bottom out of a blind hole (see Photo 1) in the front cover, allowing the bolt to rest on the plunger pad of the chain tensioner. The oil pressure couldn’t move the plunger, and the chain ran loose and beat on the guide until it broke. Then the noise got worse, mostly upon acceleration.Within a few hundred miles, the timing chain destroyed the long, straight guide on the distributor side of the engine, the chain chewed a groove in the front cover (see Photo 2) and coolant started disappearing in great amounts, winding up in the crankcase.The front cover is still available from a number of sources. The timing chain components are sold in kit form and the replacement can be performed with the engine in the vehicle and without pulling the cylinder head. If the head is off, a close inspection of the timing components, as noted above, is advisable.Teardown and Replacement
Timing chain replacement without head removal goes like this. The less bending and prying you do, the better the repair will come out. Depending on accessories, the repair will take more or less time, due to the mounting brackets.

  1. Remove the fan, shroud, drive belts and any bracket attached to the front engine cover. You will also need to remove the valve cover. Set the engine on TDC, disconnect the battery and hide the keys to the ignition.
  2. Remove the lower engine shield, then drain the radiator and crankcase. Remove the lower radiator hose from the water pump. You don’t need to remove the radiator, but it’s usually easier to see what you’re doing with it out of the way; it’s your call.
  3. Remove the crank pulley, oil pump housing and drive gear.
  4. Remove the oil pan bolts that screw into the front cover. Loosen, but don’t remove, the oil pan bolts on both sides of the crankcase.
  5. Use a sharp, stiff putty knife to separate the oil pan gasket from the bottom of the front cover. Try to keep the gasket as intact as possible to prevent small pieces from falling into the oil pan.
  6. Remove the ignition distributor, drive gear and fuel pump eccentric, and separate the camshaft sprocket from the camshaft. Remove the sprocket and let the chain settle into the chain guides.
  7. Remove the small bolt that goes into the top of the front cover (remember, it’s probably in a pool of oil so you can’t easily see it).
  8. Remove the bolts holding the front cover to the block, and the water tubes to the back of the front cover. Organize the bolts in a way that it will be obvious where they go on reassembly.
  9. Use the putty knife again to separate the front cover from the front part of the head gasket. Use great care here. Unless you want to pull the head later, try to not separate the head gasket from the bottom of the head.
  10. Carefully pry the cover away from the front of the block, making note of the alignment sleeves and their positions.
  11. Remove the rest of the timing components, guides, tensioner and crankshaft gear. Carefully inspect the front cover. If the chain has started to chew only on the cover, it may be reusable. The best determining point is to look into the water pump cavity (see Photo 3) with the pump removed to see if the grooves have been imprinted there. Once there is a failure in this area, coolant, under pressure, is just redirected into the crankcase by the water pump.

Reassembly involves carefully cleaning the front of the block, mounting the new timing components and installing per the service manual. I use RTV on the mating surfaces of the pan and head gasket. Some of the timing kits come with a replacement piece of pan gasket that requires trimming off the front of the old gasket. If the original gasket survived the separation process, it may be better left intact. As a final check before putting the valve cover on, look down the chain at the tensioner plunger and make sure there isn’t a bolt pressing on it!Oil Issues
As noted earlier, we have come to the conclusion that a lot of the timing chain failures on this engine can be eliminated by a different mindset on oil. It’s very obvious that engine noise is greater with thinner oil, the oil pressure indicated is lower and the benefits of thinner oil are negligible. So we have as a shop policy suggested stepping up to 15W/40 or 20W/50, depending on vehicle use. Since we don’t generally have the temperature extremes here in the Northwest that some of you see, you’ll need to educate yourself on the various properties of motor oil, and then determine what would be best for your part of the country.
Although there are different qualities for various viscosities of motor oil, there are also some anomalies where viscosity, thermal breakdown and low temperature pour ability are more dependent on additives than a particular weight rating.The single most important factor in motor oil failure remains the lack of preventive maintenance. Remember that it isn’t the “oil” that usually breaks down in motor oil. It’s the failure of the additives that control oxidation, foaming and maintain viscosity that causes the oil to become ineffective. I suggest you get technical information from your lubricant supplier, and make your own determination as to the best compromise for a particular vehicle, based on the normal use it will see. We keep a photo record of various engine failures in a three-ring binder. It’s become a great tool for explaining the merits of maintenance, since a picture is better than thousands of words to some customers.

Audi General Maintenance-Auto Check-Midtown Auto Service Blog-Houston,Tx

Tuesday, November 13th, 2007

Audi


GENERAL MAINTENANCE
Vital Checks on Key Vehicle Systems

by Larry Bailly, Import Specialist Contributor

From basic transportation to record-setting performance cars, Audi is a recognized leader today in innovation and cutting-edge technology. Growth in the automotive market for a broad spectrum of models has put a huge number of Audis on the road, and these cars will provide many years of potential repair and service opportunities. Getting to know the various models, repair techniques and a few shortcuts will help make repairs more routine and profitable. In this article, I’ll focus on common repairs we see on at least a weekly basis. The series of cars covered in this article will be the A4 and A6 line from 1998 to 2004. These cars are all very similar in design and equipment, and most repairs are consistent between models. Be aware that many Audi models are close cousins of VW models so they share platforms and powertrains.Increasing numbers of distinct models, multiple manufacturing plants and countries of origin, and constantly changing technology make vehicle identification ever more important (See Photo 1), especially as it relates to obtaining the proper parts and data needed to complete repairs.Most Audis will have engine and transmission ID tags that are easy to access and read. With many models, having the VIN is all that’s needed to determine the drivetrain. I won’t get into specifics in this article, but just remember that having a clear determination of the exact model and equipment will make parts ordering and repair much easier. TRANSMISSION SERVICE
With Audi service still a little foreign to some shops, we see a number of cars come in after a misdiagnosis or attempted repair that actually made the transmission operate worse than the initial complaint. The days of drain and refill or filter replacement have morphed into a job that needs to be done in a very deliberate and concise manner. Transmission dipsticks and fill tubes disappeared from most Audi models in the late 1990s and, on most models, remotely mounted coolers with accessible lines went away even earlier. On models built since 1998, the procedure to change, add or refill a transmission requires some additional steps to successfully complete a service.
Failing to get the fluid level in the transmission correct will cause shifting problems, codes to set and possible damage. There is a very delicate balance between too much and too little fluid, depending on temperature and the fill status of the torque converter. This process requires a scan tool, a means to fill the transmission while it’s elevated and running, and planning to complete the steps before the transmission temp climbs too high. Each year, model and transmission has a specific procedure, although most are based on the same principle.Following are the steps involved with performing a basic tranny service on a 2003 Audi TT, 1.8T, FWD. The design of this car differs from other Audi models and is based on the platform used by VW for a number of its models, but the fluid changing procedure is the same.This car came from another shop with erratic, sometimes delayed, shifting, and the customer felt the transmission was slipping. A quick inspection showed no fault codes, a dent in the transmission pan (See Photo 2), a fluid level inspection plug that had been removed, but a fill plug that hadn’t been removed since the factory installed it.This car does not have a dipstick, fill tube or “drain” plug. The small level check plug on the pan is an access point for the fluid level tube (See Photo 3). If the transmission is “cold” (under 30° C), removing this plug will allow some fluid to escape, which makes performing a refill procedure necessary. Failing to properly go through the refill steps will cause shifting problems and potential damage. In short: If the transmission has no fault codes, take the time to explain and recommend a transmission service and refill as a first step. Bear in mind that special fluid, tools and equipment will be needed, so be prepared before you pull that plug.In this case, the dent in the pan appeared to be large enough that there could be internal damage; on earlier models this type of impact has dislodged the filter from the valve body. Though that was not the case here, it was a reasonable assumption and needed to be investigated. At this point, it was discovered that there was yet another new type of fluid for VAG cars and we ordered that along with a filter and pan gasket. Due to the cost of these transaxles, substituting another fluid isn’t advisable. When the check plug was pulled with the transmission cold, there were about three drops of fluid that came out. There should have been more. Even with the level-checking tube removed, there was probably only about a quart of fluid in the pan. I don’t know why, as there were no significant leaks, but since this was a new car for the customer, there was no service history.The pan was pulled and a basic inspection revealed no internal damage (See Photo 4), discolored but not burnt fluid and a filter that showed very few impurities. A point worth noting here is that the filter is actually a metal screen that when wet looks like a piece of sheet metal because it’s so fine. We replaced it in this case since it took a week to get it. Unless it’s seriously contaminated, a thorough cleaning could allow it to be reused.With the pan and new gasket in place, the level tube was reinstalled but not the level-check plug. The filling bottle was prepared with the new fluid, and hung from the hood latch loop (See Photo 5). Although the factory fill bottle isn’t absolutely necessary, it has paid for itself in allowing this job to be completed in a much more controllable manner. In this case, the filler plug is on the differential housing, high on the back of the transaxle. It took a couple of hits with an air hammer to get it to move, but with a 55 torx bit it was removed and the O-ring seal was inspected.To start the procedure, the transmission temperature must be under 30° C, with the dispenser valve and tube inserted in the fill hole (See Photo 6). On other VAG cars, the hooked end of the dispenser makes more sense. The valve is turned to the open position and fluid fills the transmission pan until it starts to drip from the check hole. With the dispensing valve closed, the car is lowered and a scanner is attached to the DLC connector under the dash.After carefully inspecting the route of the fill hose and running the lead from the scanner to a place where it can be read with the car on a lift, start the car in park and let it idle. Raise the car in the air and allow the transmission fluid to warm while monitoring with the scanner. A less precise way to do this would be to use a temp probe or non-contact thermometer, but getting actual fluid temps this way could be difficult.As the fluid temp rises above 30° C, open the dispensing valve and allow the transmission to fill. It will take a few minutes, so keep track of the fluid temp and watch for the fluid to start spilling out of the checking hole. It will be obvious that by not filling in this manner, it would be impossible to get enough fluid into the transmission for proper operation, or result in grossly overfilling and causing similar problems or leaks due to excess fluid.Once the fluid has reached 40° C (higher in warmer climates; see the workshop manual), add or remove fluid until there is just a small amount of fluid coming from the level check hole. Remove the filler unit and install the plugs at the check hole and filler hole.Check for leaks and do a road-test. A final check for codes is a good idea. This service often makes a significant difference in tranny operation, and will most likely save your customer a lot of money and gain you a new customer for life.FINDING THE SOURCE OF LEAKS
Leak detection and repair can be a constant struggle for any shop. Tracing the actual source of a minor leak is always a challenge. With engine compartments getting smaller and crammed with even more equipment, even a small leak can require removing a number of components to actually determine the leak’s source. For example, a leak appeared to be coming from under a twin-turbo A6, at the rear face of the engine — possibly a head gasket or coolant transfer tube. After removing the intake manifold, the source was obvious; however, there is an auxiliary coolant pump (See Photo 7) mounted in the valley between the heads.
Other common leak points with these engines are oil leaks at the valve (cam) covers, and at the valley pan on early models. Both of these leak points require some investigation to determine the actual source before repair.BELTS
I’ve covered the timing belt replacement procedures on these cars with the V6 engines in previous articles. The procedure for the 4-cylinder models is similar, but, in most cases, the space restrictions are even worse. The removal of the front bumper cover (See Photo 8)and movement of the core support (lock carrier in VAG speak) to the service position is mandatory. On the TT, the procedure is the same as on the New Beetle, and just as tight.This is one repair where it’s very important to know exactly which engine series you’re working on. There have been a number of design changes and different repair procedures as well as updated parts to consider when replacing the belts on the 4-cylinder turbo cars. The basic differences are whether the water pump is externally mounted and driven by a serp belt, or internally driven by the timing belt. The same failures of the water pump impeller occur on these engines as on VW engines. An inspection of the water pump while the timing belt is off is a good idea, if you don’t have an automatic replacement policy. On the models with the external water pump, it’s easier to remove the thermostat cover than the water pump to inspect for a cracked or otherwise damaged impeller.One tip for this job is that the belt is barely long enough to reinstall, even with the tensioner locked in the relaxed position. Be extremely careful to double-check the timing marks before starting, and it’s always a good idea to turn the engine over by hand several times to check for interference. Depending on the engine code, there will be two or three external belts. On some models, the power steering belt is a non-adjustable type with a split pulley for removal and installation, so having the exact replacement belt is very important.UNDERCAR SERVICE
There are two specific areas to look for service under these cars: the front brake flex lines and the front suspension.
The front brake flex lines on these cars tend to crack at the connection point to the caliper. Although the manufacturer has recalled some of these cars for this fault, not all are covered. Even if you’re not doing brake work, this is one inspection that should be done on every VAG car that comes into your shop. Replacement hoses are readily available, but again, specific hoses are needed depending on how the car is equipped.Like the cautions above concerning identification of the engine and transmission, there are several very different brake systems used throughout this model run, so be ready to pick parts based on rotor diameter and caliper design.The front suspensions on the A4 and A6 cars are a multiple-link system with up to four ball joints. The ball joints are not replaceable, but instead need to be replaced with their respective suspension arm. Most problems are with the upper ball joints where they attach to the bearing carrier. By grasping the wheel front and rear, and turning (steering action) slightly, the joints will very obviously show wear and movement. Do not mistake this movement for the tie rod ends, which are also prone to failure on the earlier models in this series (many were recalled).Adding Audi to the list of models serviced by any shop will ensure maintenance work for a long time to come. Since many tools, parts and software interchange with VW models, the purchase of model-specific equipment is well worth the investment.


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