WHINE/SLOW OR SLIPPING/180-C CHECK TRANS OIL LINE PRESSURE

VEHICLES AFFECTED: 'T' Series Vehicles Equipped With 180-C Transmissions

Some THM 180-C transmissions built before serial number TP 2928976 (Fig. 1) may exhibit a whining noise and/or slow or slipping engagement in all ranges. The noise increases when the engine RPM is increased. This wining noise is similar to noise caused from the steering wheel being turned to its maximum travel.

If the above condition is experienced, check the transmission oil line pressure. (Refer to the service manual for procedure). If the line pressure is low, refer to the following service procedure.

Remove the oil filter and visually inspect for restriction.

If the oil filter is restricted, remove the transmission from the vehicle, and remove the pump.

After removing the pump, inspect the selective end play washer for wear especially on the inside diameter of the washer. If the washer is worn, replace tbe oil pump assembly and selective end play washer, using service package 96040245. This package contains the pump assembly and selective end play washer.

If the oil filter is not restricted, refer to the proper service manual for additional diagnostic procedures.

Starting March 22, 1984, serial number 2928976, a new oil pump assembly and selective end play washer went into production on all THM 180-C transmissions. The new oil pump assembly has a casting change to accommodate the new selective end-play washer. The new end play washer (Fig. 2) has 3 raised tabs to hold the washer stationary on the pump.

NOTE: The new end play washer is not interchangeable with the past oil pump assembly.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.