Service Slants

Motor,  Oct 2006  by Rosario, Tom

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GM Truck

Engine oil leakage. An owner of a 2001-05 2500- or 3500-series Chevy Silverado or GMC Sierra with the 6.6L Duramax diesel may show up in your shop complaining that there are drops of engine oil on his driveway. One likely area of the leak is at the interface between the oil cooler and engine block. GM says the block may have casting imperfections that allow oil under pressure to leach out past the O-ring seals on the cooler. The oil then travels down the cooler onto the surface below.

To make a definitive diagnosis, get the truck in the air and have a good look around. Pay special attention to the main bearing cap side bolts, because leaks at the bolts can appear to come from the cooler. If you can definitely trace the leak as coming from the oil cooler, remove the cooler from the engine. Now turn it over to the flange side and remove the old O-rings, installing two new ones in their place. Using the illustration at right as a guide, coat the area around the O-rings with a special sealant (Part No. 12378521), as shown. Make sure the sealant doesn't get into the O-ring grooves, and work quickly at installing the cooler because you have about 20 minutes before the sealer takes a set. To complete the repair, fill the engine with oil, wait two hours, then fire the engine up and check for leaks.

Chrysler

Brake noise. Owners of 2004 all-wheel-drive Pacifica models built on or before 6/9/03 may come in complaining of an annoying squeal or squeak from the front brakes under light pedal application while driving in Reverse. Chrysler says the noise typically occurs after an extended soak in temperatures below 45°F, and is most likely due to design incompatibilities between the brake calipers and supports. Installing new-design caliper supports (Part No. 05134356AA, right; 05234357AA, left), along with updated front brake pads (Part No. 05134358AA), should eliminate the brake noise immediately.

Ford

Instrument panel rattle. Some 2001-04 Mustangs may produce an annoying rattling sound from the instrument panel. In addition, the climate control vents may be difficult or impossible to adjust. Both problems are likely due to one or more detached vanes in the vent housing(s).

A new-design, better quality vent housing (Part No. 3R3Z-19893-AB) is now available to put the annoyance to bed. To install it, pry out the defective housing from the instrument panel with a flatblade screwdriver, then simply press the updated housing into place in the dash. Repeat the drill for all affected vents.

Acura

Noise from rear wheel(s). The driver of a 1995-98 2.5TL or 1996-98 3.2TL may come into your shop one day complaining of a growl or whine from one or both rear wheels. When he does, get the car on the road pronto and see if the noise changes pitch as you increase and decrease vehicle speed. If it does change pitch, says Acura, chances are one or both rear hub bearings are contaminated with water. The water finds its way to the bearing by following a path from the wheel to the brake caliper, where it then enters the bearing internals through a defective grease seal.

Installing new-design parts from a wheel bearing kit (Part No. 06427-SW5-305, 2.5TLs; 06427-SZ5-305," 3.2TLs) should stamp out the noise and prevent future troubles. Included in the kit are two rear hub bearing assemblies, two splash guards, two spindle nuts and two grease caps.

GM Truck

Fluctuating idle, hesitation, delayed 1-2 upshift. Owners of 2002 Chevy TrailBlazers, CMC Envoys and Olds Bravadas (all with the 4.2L engine) may complain of a potpourri of driveability problems. Among the comments you might hear are that the idle fluctuates on startup after an overnight soak at higher altitudes, that the engine hesitates on acceleration when the coolant temperature is between 140° and 175°F or that the transmission won't perform a 1-2 upshift until the throttle is opened more than 25% and the coolant temperature is between 45° and 85°F.

Begin your diagnosis by hooking up a scan tool and checking for relevant DTCs. If no codes are stored, says GM, the PCM needs to be flashed with new software files. You'll find the updated calibration in software revision TIS 2,5/2003 and later.

Dodge Truck/Jeep

Refrigerant leak. If you encounter an a/c leak on 1997-98 Dodge Dakotas and Jeep Cherokees and Wranglers, don't overlook the hose manifold-to-compressor connection or you could be setting yourself up for needless work. Apparently, the bolt that retains the manifold on these trucks bottoms out in the compressor before adequate torque can be applied to produce a sufficient seal. Installing a flat washer under the bolt and topping off the refrigerant charge is the simple yet permanent solution.

Pontiac

Inadequate a/c performance. Owners of 2003 Vibe models may complain that the a/c system isn't producing enough cold air. According to Pontiac, one likely cause for the problem is a misadjusted temperature control cable. Readjusting the cable should bring back the cool air immediately.