Engine - Stops Running When A/T is Placed in Reverse
85buick04Bulletin 86-7200-1
Date Nov. '85
Ref.No. 86-030-7200
SUBJECT: ENGINE STOPS RUNNING WHEN TRANSMISSION IS PLACED IN REVERSE RANGE
MODELS AFFECTED: 1984-1986 THM 200C TRANSMISSIONS
200-C PRESSURE REGULATOR VALVE:
Some vehicles equipped with 1984, 1985 and early 1986 THM 200C transmissions may exhibit a condition which could 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 torque converter clutch (TCC) to engage.
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 and is scheduled for mid 1986 production.
In the meantime, if this condition exists on one of the above units, 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.