ENGINE STALLS IN REVERSE 200C INSTALL PRESSURE VALVE

VEHICLES AFFECTED: 1984-1986 THM 200C Transmissions

Some vehicles equipped with 1984, 1985, and early 1986 THM 200C transmissions may exhibit a condition which may cause the engine to stop running when the transmission is placed in reverse range. This condition may be caused by transmission fluid leaking across the pump gear causing the torgue converter clutch (TCC) to engage. This conditon can be aggravated by hot transmission oil, high line pressure demand, low idle speed, and large pump drive gear side clearance.

A pressure regulator valve with two flats ground between line and converter feed lands (Refer to Illustration) will prevent transmission fluid leakage across the pump. It is scheduled for mid 1986 production.

If this condition exists, order and install service package, Part Number 8638951, which contains a pressure regulator valve, Part Number 8638950, and instruction sheet, Part Number 8638952. Refer to the appropriate Service Information Manual for proper installation procedures.

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.