NEW OIL PUMP SHAFT SEALH REPLACEMENT PROCEDURE

Beginning August, 1981, all 1982 "J" car THM 125C transmissions have a new oil pump shaft seal. The 1982 "A" and "X" car THM 125C transmissions are being built with the new oil pump shaft seal at the start of production. This new oil pump shaft seal will assure adequate converter clutch apply oil pressure. See Figure 1.

Please add the following oil pump shaft seal and the bearing assembly replacement procedure to the 125C section of your 1982 Service Manual.

(1) To remove only the oil pump shaft seal, pry out with screwdriver.

(2) To remove the bearing assembly and the oil pump shaft seal, use tool J-28698 and J-7079-2. Drive out toward case cover side. See Figure 2.

(3) Install the new bearing using tool J-28698 and J-7079-2.Install until the bearing is 1.00mm to 1.20mm (.040" to .047") above the pump pocket face. Check this dimension with feeler gage. See Figure 3.

(4) Install the new oil pump shaft seal using tool J-28698 and J-7079-2. Install seal with steel side up from the case cover side. Install until the pump shaft seal is 0.50mm (0.020") above the surface to flush. DO NOT drive the oil pump shaft seal below the surface. See Figure 4.

(5) Recheck the bearing assembly to make sure the bearing cup is 1.00mm to 1.20mm (.040" to .047") above pump pocket face.

When a control valve oil pump assembly is installed on car be certain the oil pump shaft is completely seated in the control valve valve oil pump assembly before installing. The new oil pump shaft seal may be used on all THM 125C transmissions.

The service part numbers are as follows:

Oil Pump Shaft Bearing Assembly 8631277 Oil Pump Shaft Seal Assembly 8637569

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.