Service Slants

Motor, Feb 2005 by Rosario, Tom

Jeep

Oil leakage. Some 1997-2005 Wranglers with the 4.0L Six and manual gearbox (build date prior to 9/2/04) may leak or weep oil from the area of the rear main bearing seal. What's really newsworthy here is what causes the oil seepage-dirt or road debris accumulating around the outside edge of the main seal, which damages the seal and affects its ability to properly seal off the lube.

Jeep says the problem is much more prevalent on vehicles that are subjected to off-road usage, and is due to a small gap at the top of the adapter plate between the engine and transmission bellhousing. It's this small gap that allows the junk in and causes all the headaches. Sealing it off with RTV should help eliminate future problems. Here's how to go about it:

Start by opening the hood and positioning yourself on the drivers side of the engine. Now locate the adapter plate. The area you want to hit with the RTV sealant is at the top of the bellhousing, indicated by the dotted oval in the illustration at right. Before doing so, though, clean the area with spray carburetor or throttle body cleaner so the sealant adheres to the metal. Now wipe off any residue and let the cleaner air-dry. Finally, squeeze enough RTV from the tube to completely cover the area indicated, allow it to take a set, close the hood and you're done with the repair.

GM Truck

Unstable idle, hesitation, shifting complaints. GM notes that some of its 2002 4.2L Chevy TrailBlazers, GMC Envoys and Olds Bravadas can exhibit a host of seemingly unrelated driveability problems. Among the customer complaints you're likely to hear are that the idle fluctuates incessantly on initial startup following an overnight soak at higher altitudes, that there's a wicked hesitation on acceleration at operating temperatures below 175°F or that the transmission delays or won't perform a 1-2 upshift until the throttle is opened greater than 25% and the engine coolant is above 85°F.

Naturally, you'll want to begin diagnosis with a thorough scan check of the PCM. Take care of all relevant DTCs, then clear the codes and take to the road to ensure that the problem(s) has been eliminated. If no codes are logged, however, the only real solution is to reflash the PCM with new software files, says GM. You'll find the updated calibration in software revision TIS 2.5/2003, which became available on 2/22/03.

Ford

MIL illuminated, DTCs stored. Some 2001-02 flexible fuel (FFV) Taurus and Sable models with the 3.0L V6 can turn on the MIL and store DTC P0172 and/or P0175 in computer memory. If you're thinking of replacing the MAF sensor, the front O2 sensors or the PCM, don't, says Ford, it won't do you any good. Reprogramming the PCM with updated software will. Use WDS release B32.8 or higher. You can also download the new calibration files from Ford's website at www.motor craft.com.

Chrysler

Power steering fluid warning. Chrysler reports that many of its 2004-05 vehicles (full list below) can suffer severe damage to the power steering system if the wrong fluid is used to replenish or top off the system. Most at fault are fluids or supplements containing Teflon, which has a nasty habit of clogging or restricting the mesh filter in the pump reservoir. That, of course, leads to pump starvation and the eventual demise of the pump and, possibly, the steering rack.

When servicing a late-model Chrysler power steering system, the carmaker recommends using genuine Mopar fluid or an equivalent. In a pinch, you can also use ATF 4 transmission fluid, with no ill effects.

Vehicles that have the mesh filter and are most susceptible to the problem are: 2004-05 Pacifica, Sebring, Stratus, Neon, SRT4, PT Cruiser, minivan (Town & Country, Caravan, Voyager) and Viper models, and 2005 300s and Magnums.

Dodge Truck

Rattling noise from transmission. Dodge wants you to know that some 2003 Ram Trucks equipped with the 5.9L Cummins turbodiesel and sixspeed manual gearbox (build date on or before 5/11/03) are prone to giving off an annoying rattling sound from the tranny while idling with the gearshift lever in Neutral. Insufficient tension in the clutch disc springs is the likely cause of the noise complaint.

To check things out, set the parking brake, place the transmission in Neutral and start the engine. If you hear the noise, depress the clutch pedal and see if the rattling sound goes away. If it does, that tells you that the clutch springs just aren't up to the job at hand. Replacing the clutch disc with a newdesign unit (Part No. 52107775AC) with upgraded, beefier springs should help restore some peace and quiet. Figure about 2.6 hours labor to complete the parts swap.

Hyundai

Barking up the wrong diagnostic tree. If you're one of those guys who follows trouble trees to the letter when a hard code is stored, be on your toes when diagnosing DTC 1372 on a 2002 Elantra, Sonata or Santa Fe, or a 2003 Tiburon. That's because the factory repair manuals for these models have a major gaffe in the diagnostic flow chart for the code.

Here's the deal: Code 1372 sets when the measured time for a 120° rotation of the crankshaft varies too much from one segment to another. The time is analyzed by the PCM based on signals from the crank sensor. So it's pretty obvious that it's the operation of the crank sensor that should be checked whenever DTC 1372 stores hard. Problem is, the repair manuals for these vehicles tell you to check the signal from the right front wheel speed sensor to the PCM. Odd? Sure! But if you're not paying attention, that could lead to hours of frustrating diagnosis. To be on the safe side, cross out any reference to "right front wheel speed sensor" in the trouble trees for the above-mentioned vehicles and replace it with "crank sensor." That goes for aftermarket manuals, as well.