TRANSMISSION OIL PAN LEAKS NEW OIL PAN200-200C

MODELS: 1983 AND PRIOR LIGHT DUTY TRUCKS WITH THM 200C TRANSMISSION

Beginning September 6, 1983, a new transmission oil pan (Figure No. 1) and hex head screw and conical washer assembly (Figure No. 2) went into production for all THM 200C transmissions.

Refer to the chart below and verify serial and model numbers. If the serial number is prior to the number on the chart, then follow this procedure.

MODEL SERIAL ----- ------ BH 48567 OI 17716 CZ 1041 JY 1074 OR 1071 OU 1724

SERVICE PROCEDURE:

1. Diagnose source of leak to be certain leak is from the transmission oil pan area. (Refer to service bulletin 83-B-11 for diagnosing transmission oil leaks).

2. If a leak is determined to be from the transmission oil pan area:

Remove the oil pan and gasket.

Clean the case oil pan face (with solvent) and visually inspect the case oil pan face for nicks, and R.T.V. sealant (room temperature vulcanizing sealant). Make sure all R.T.V. sealant is removed from the case oil pan face.

3. If the THM 200 transmission being serviced is a 1979 or earlier model, verify which transmis sion oil screen is being used. (Figure No. 3) If the old oil screen is being used (Figure No. 3), it must be replaced with the new oil screen (Figure No. 3) provided in the service package.

4. Replace the former oil pan (Figure No. 1) hex head screws (Figure No. 2) with new oil pan (Figure No. 1) and hex head screw and conical washer assemblies (Figure No. 2). Order service package 8638929. This service package contains the following:

1 - 8648160 - New Oil Pan 1 - 8648161 - Transmission Oil Pan Gasket 11 - 8643693 - Hex Head Screw and Conical Washer Assembly 1 - 8630789 - Screen Assembly Transmission Oil 1 - 8628300 - Gasket, Screen to Valve Body 1 - 8632952 - Instruction Sheet

These parts are also available separately.

Torque all hex head screws to 11.0 N.M. (9.0 ft. lbs.) then retorque all the hex head screws a second time to the same specifications as above. The second retorque is important because the gasket material relaxes after the first tightening.

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.