Service slants

Motor,  Jun 2002  by Marcy, Thomas

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Infiniti

Contaminated transmission oil cooler. When you repair, overhaul or replace an automatic transmission on 1990 and later models, except Q45s (G50s) with a transmission filter, Infiniti stresses that you must inspect and clean the oil cooler mounted in the engine radiator for metal debris and friction material that often get trapped inside. Upon startup, the debris then contaminates the oil, and may block or restrict its flow. In either case, failure of the newly serviced tranny can result.

When contamination enters the cooler inlet, it's necessary to backflush the cooler to rid the circuit of any built-up debris. To begin the fix, first inspect the cooler fluid using a white coffee filter. Drain cooled fluid from the inlet hoses into the filter and inspect it for debris. Metal powder or debris less than lmm (.040 inch) in size in the filter is considered normal, and the oil cooler and radiator can simply be reused. If the debris is larger, however, clean the cooling circuit before reuse.

Infiniti advises that the cooler inlet and outlet vary from model to model. Therefore, identify the connections before you clean the unit. Also note that 1992 Q45s/G50s after VIN JNKNG01C(*)NM205387 and all 1993 Q45s/G50s are equipped with a twin oil cooler system. Do the cleaning procedure for both cooler units on these models.

Wear safety glasses and rubber gloves when spraying any transmission cooler cleaning agent and ensure adequate ventilation. Do not breathe vapors or spray mist. Infiniti suggests that you spray the cooler cleaner in a continuous stream into the outlet until fluid flows out of the inlet hose for about five seconds. Next, insert an air gun tip into the outlet. Blow compressed air regulated to 70 to 130 psi through the outlet hose for 10 seconds to force out any remaining fluid. Position yourself so the cleaner doesn't strike exposed skin and you don't inhale it. Perform this step several times to ensure a clean circuit.

Now position an oil drain pan under the banjo bolts that connect the oil cooler steel lines to the transmission, then remove the banjo bolts. Flush each steel line from the cooler side back toward the transmission by spraying the cleaner in a continuous stream for about five seconds. Next, blow 70to 130-psi compressed air through each steel line from the cooler side back toward the transmission for about ten seconds to force out any remaining fluid and contaminants. Make sure all debris is ejected from the steel cooler lines, banjo bolts and fittings. Lastly; reconnect all cooler lines and refill the transmission and cooler to the recommended levels.

GM Truck

Front suspension noise. Some 1999-- 2000 GMC and Chevy C/K trucks exhibit a clunking or banging noise, most noticeable when driving slowly over bumps or backing out of a driveway. According to GM, the cause may be the coil springs contacting the vehicle frame. For these vehicles, a new-design front spring insulator (Part No. 15756770) should eliminate the noise.

Chrysler

High shifter effort. Some 2000 Dakotas and Ram Trucks and Jeep Wranglers and Cherokees equipped with an NV3500 (DDC) or NV3550 (DDD) five-speed manual transmission may require high shift lever effort when the driver shifts out of a gear. This condition may commonly arise when either a 2nd-to-3rd upshift or 5th-to-4th downshift is attempted. Other shift patterns may also require high shift effort when coming out of the original gear. In most cases, these latter shift patterns are less common. The cure for the difficulty involves replacement and lubrication of the fivespeed manual transmission's shift shaft detent plunger.

To begin the fix, access the shift shaft detent plug. On a Dakota or Ram Truck, you've got to do it from under the vehicle, so get the vehicle on a lift. The detent plug is located on the driver's side of the transmission, in the recessed area above the clutch slave cylinder. On a Cherokee or Wrangler, you can access the shift shaft detent plug from inside the vehicle. Remove the gear shift knob, the gear shift lever boot and bezel, the center console, the inner gear shift boot and the floor pan cover. The detent plug is located on top of the transmission and immediately to the rear of the shift tower.

Now remove the detent plug, spring and plunger. Note that on Cherokees and Wranglers, access to the shaft detent plug may be too tight to alow use of special tool 8117A to remove the plug.

Carefully pry off the detent plug evenly around its top lip. Liberally lube the inside and outside of the new shift shaft detent plunger (Part No. 05016233AA) with lubricating grease containing molybdenum disulfide, and which has an operating temperature range of at least -40 deg to 350 deg F.

Install the new plunger and the original spring into the transmission bore, then the new detent plug (Part No. 04741128). Make sure the detent plug fully seats to the transmission housing. On Cherokees or Wranglers, reinstall the floor pan cover, the inner gearshift boot, the center console, the gear shift lever boot and bezel and the gear shift knob.