NEW 2-4 SERVO COVER AND SEAL SERVICE INFORMATION. GMC Truck S15 Pickup - 2WD 1983

For 1990-2009 cars

# NEW 2-4 SERVO COVER AND SEAL SERVICE INFORMATION

#### MODELS: 1982-1984 L,K,S,T WITH THM 700-R4 TRANSMISSION

Beginning April, 1983, all THM 700-R4 trans- missions were built with a new 24 servo cover and seal. This change provides a tighter fit between the case servo bore and the 2-4 servo cover.

The new servo cover "O" ring (part number 8647351) is identified with a green stripe. This is to distinguish it from the past "O" ring (part number 8642112) which is sitill used on the second apply piston. Refer to Figure No. 2. numbers 14 and 21 for correct location of "O" rings.

#### NOTE: The past servo "O" ring (part number 8642112) cannot be u#sed with the new servo cover, if used together they will leak.

#### SERVICE INFORMATION

If a leak is found at the 2-4 servo cover.

1. Remove the 24 servo cover and "O" ring seal.

2. Check the case servo bore for sharp edges especially at the recessed slots. See Figure No. 1.

3. Check the case servo bore for burrs, nicks or damage on sealing wall. If damage is found replace the case.

4. Check the 2-4 servo cover for porosity or damage. If required, replace with part number 8642979 which will contain a new 2-4 servo cover and "O" ring seal.

5. If it is necessry to replace only the "O" ring seal, use part number 8647351.

6. When installing the 24 servo cover and "O" ring seal, lubricate the seal with petrolatum or equivalent and use care not to cut the seal during 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.