LOSS OF POWER/DELAYED ENGAGE THM325-4L DIAG.AND REPAIR

MODELS AFFECTED: 1982 & 1983 THM 325-4L Transmissions - All Models

Some 1982 and 1983 vehicles equipped with a THM 325-4L transmission may exhibit an apparent loss of engine power. This condition may be caused by an incorrect application of the low and reverse clutch assembly, during third speed operation.

This condition is caused by a missing coiled spring pin that is used for locating the Lo-1st detent valve bushing in the control valve assembly.(Figure #1). The absence of the coiled spring pin allows the Lo-1st detent valve bushing to rotate in its bore, allowing detent oil to apply the low and reverse clutch.

When servicing any 1982 and 1983 THM 325-4L for this apparent loss of engine power condition, inspect the Lo-1st detent valve bushing for correct orientation in its bore (Figure #1). If the bushing is found misoriented and the coiled spring is missing, reorientate the bushing in its bore and install a coiled spring pin (Part #8628400).

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.