ERRATIC SHIFT 200 & 200C DAMAGED/ROLLED GOV. SEALS

MODELS AFFECTED: 1976 THROUGH 1980 THM 200 AND 1978 THROUGH 1987 THM 200C EQUIPPED VEHICLES

A 1978 through 1987 vehicle equipped with THM 200 or THM 200C transmission (See Figure 1) may have erratic shift patterns (such as late or no upshifts) due to an O-ring seal on the governor cover assembly causing incorrect governor pressure. NOTE: The erratic shift pattern may be more noticeable after transmission reaches nomal operating ternperature.

Remove the cover (on car service) and inspect the internal governor cover seal (37) (Refer to Figure 2). If damaged or rolled, replace the entire governor cover assembly (36). The seal is not available separately.

IMPORTANT: INTERNAL GOVERNOR COVER SEALS MUST BE WELL LUBRICATED WITH PETROLEUM (PETROLEUM JELLY) TO PREVENT DAMAGE OR ROLLING DURING INSTALLATION.

Service Parts Information:

8628933 THM 200C Governor Cover Assembly (with seals 35 and 37).

Service Manual Reference:

Refer to the Automatic Transmission Unit repair section of the 1987 THM 200C Service Manual for proper installation.

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.