LATE ENGAGE/SLIP IN DRIVE/200C BLOCKED FOR. CLUTCH OIL HOLE

VEHICLES AFFECTED: 1984 Vehicles Equipped with THM 200-C Transmission

Some early 1984 model THM 200-C transmissions may experience a late engagement or slipping in drive range. This condition is usually detected while the transmission is cold, and could be caused by a blocked forward clutch feed orifice hole. (Figure #1)

Other causes for late engagement or slipping in drive are, low transmission oil level cut or nicked forward clutch piston seals and/or cut or nicked teflon turbine shaft seals.

This bulletin is for early 1984 model THM 200-C transmissions. Refer to the chart below and verify serial and model number. If the serial number is prior to the number on the chart then follow this procedure.

MODEL SERIAL NUMBER ----- -------------

BH 54628 OI 21738 CZ 1041 JY 1075 OR 1119 OU 1727

SERVICE PROCEDURE:

1. Check transmission oil level correct if required.

2. Visually inspect the forward clutch piston seals and turbine shaft teflon seals for cuts and nicks.

3. Using a 1/16 allen wrench mark short end as illustrated in Figure 2. Using the allen wrench as a gauge insert the small end into the forward clutch feed orifice hole (Figure 3) and make sure the allen wrench goes into the orifice hole (without any drag) until the mark on the wrench is flush with the ground diameter (Figure 3).

If it is necessary to replace any of the parts listed in this bulletin refer to chart below:

Housing Assembly Forward clutch Turbine Shaft Model Forward Clutch Piston Seals Seals (Teflon) ----- -------------- ------------- -------------- CZ, JY 8633948 8628924 All Models BH,OI 8638944 8628924 8628090 OR, OU

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.