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Automotive Industry

Service Slants

Motor, Dec 2003 by Savasta, Bob

GM Truck

Rear main seal leakage. Some 2002-03 Chevy and GMC C/K pickups with the 6.6L Duramax diesel may leak oil from the rear main seal in extremely cold temperatures-typically -20°F or below. According to GM, the problem is most likely the result of a restriction in the PCV system of the big "oil-burner." Nothing unusual there, but what's interesting is what causes the restriction-accumulated water in the vent tube for the PCV oil separator housing. During the temperature extremes noted above, the water freezes. That creates a blockage in the PCV system and causes the crankcase pressures to soar. It's these high pressures that cause the seal leakage.

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Diagnosing the problem in the shop can be difficult, says the General, because the higher temperatures will most likely thaw the ice before you can take a pressure reading. Creating a secondary atmospheric vent path for the oil separator housing should alleviate the problem.

To do this, first remove the alternator bracket, then flip the bracket over and remove the oil separator cover bolts, cover and gasket. Using a 25/64-in. bit, drill a hole in the back of the alternator bracket and through the housing in the location shown in the illustration. Make sure the hole is located above the vent tube. Clean the metal shavings from the housing, then reinstall the oil separator cover and bolts using a new gasket. To complete the fix, torque the cover bolts to 71 in.-lbs., then reinstall the alternator bracket.

Chrysler

No-start, long crank times, MIL illumination. Some 2003 Chrysler cars and minivans (complete list below) may exhibit no-start problems, long crank times and/or MIL illumination, with any or all of the following DTCs stored in PCM memory: P0016, P0335, P0339, P0340, P0462, P0498, P0499, P0522, P0622, P1604, P1681 and P1686.

With so many codes present, you might be inclined to think that the PCM has gone wacko and is in need of some fresh, new software. And you'd be right! If you have the capability, reprogram the black box using the DRB III and software operating at level CIS CD2137 or higher. Don't forget to fill out an authorized software update label and affix it to the PCM when the job is done.

Vehicles that are susceptible to the problem and can benefit from the PCM reflashing are 2003 Neons and PT Cruisers built before 9/25/02 and 2003 2.4L-equipped Town & Countrys, Caravans and Voyagers built before 5/7/03.

Ford Truck

Engine ticking. Some 1997-99 Ford trucks and minivans with the 3.8 (VIN 4) or 4.2L (VIN 2) engine may produce a ticking sound that's reminiscent of valvetrain noise. According to the Automotive Engine Rebuilders Association (AERA), there's a good chance that the ruckus is actually caused by abnormal contact between the bottom of the piston skirts and the crankshaft counterweights, due to bent connecting rods.

The cause for the bent rods, say AERA members, is a hydrolock condition that sets up as coolant from a leaking intake gasket makes its way into the cylinders, typically in the front part of the engine. Coolant can't be compressed, so even a small leak can shorten a rod by .030 to .040 in. And that's all it takes to cause the unhappy marriage between the piston and crank. Gross leaks will typically result in the rod shattering into two pieces.

Diagnosing the condition can be tricky, AERA reports, because the misfire monitor has a wide range of coverage and may be reluctant to spit out a DTC. Fortunately, a cranking compression test should point you in the right direction, with the compression lower in the cylinders affected by the bent rods.

AERA points out that Ford went to a different-style intake gasket for the 3.8 and 4.2 in 1999, so the chance of coolant leaking into the cylinders and causing damage to the rods is reduced on later-model trucks.

Acura

Front suspension noise. Acura reveals that some of its 1996-98 3.5RL models are prone to giving off an annoying knocking sound from the front end when going over irregular road surfaces such as bumps or dips. The Japanese carmaker has concluded that wear in the upper control arm bearings (part of the front anchor bolt assemblies) is the most likely cause of the noise.

To home in on the diagnosis, road-test the vehicle to determine where the noise is coming from. If it's indeed coming from the front suspension, drive back to the shop and get the vehicle up on a lift. Next, head for the comer of the car you think is making the noise, reach in over the tire and place your hand over the upper arm bearing. Now hit the upper portion of the tire sharply with a large rubber mallet. Repeat the exercise at the other bearing. If you feel looseness in the bearing(s) or hear the knocking noise, replace the front anchor bolt(s) with a new design (Part No. 51010-SZ3-000).

Jeep

Brake moan. Some 2003 Liberty trucks (build date prior to 4/15/03) may give off a moaning noise from the rear brakes during light pedal application. According to Jeep engineers, the noise usually occurs during the first stops of the day in ambient temperatures below 50°F, and is the result of moisture infiltration into the lining material of the rear brake pads. New-design pads (Part No. 05083882AE) that are more moisture-tolerant are now available to alleviate the concern. When installing the revised pads, make sure the calipers are clean and dry, to allow the adhesive backing on each new pad to take a good set to the caliper mating surface.

Automotive Industry

Service Slants

Motor, Dec 2003 by Savasta, Bob

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