SLIPPING OR NO DRIVE/THM325-4L LOOSE OR MISSING CUP PLUG

MODELS AFFECTED: ALL 1983 THM 325-4L TRANSMISSIONS

Some 1983 THM 325-4L transmissions may experience a slipping or no drive condition. This condition, while not noticeable in reverse, could be caused by a missing or loose solid cup plug in the input shaft of the forward clutch assembly.

When servicing any 1983 THM 325-4L transmission for a slipping or a no drive condition, and the forward clutch assembly shows signs of burning, inspect the housing end of the input shaft which is part of the forward clutch assembly (Figure 1). If the solid cup plug is missing or loose, you will lose apply pressure to the forward clutch piston, and a no drive or slipping condition will result. If the cup plug is missing, it must be located before reassembly of the transmission. It could possibly be in the open end of the output shaft (Figure 2). Simply tape the end of the output shaft on a table to remove it.

Replace the cup plug using a new plug Part #8628145. Apply a thin coat of Loctite (or equivalent) to the plug. Using a 5/16" punch, install the plug in the larger of the two holes in the shaft until it is 1.0mm (.039 in.) below surface and reassemble unit.

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.