A/T - New 2-4 Servo Cover and Seal
Number: 83-I-115Section: VIIc
Date: Feb., 1984
Subject: NEW 2-4 SERVO COVER AND SEAL
Model and Year: ALL THM 700-R4
TO: ALL CHEVROLET DEALERS
This cancels and replaces Chevrolet Dealer Service Information Bulletin 83-I-115 dated September, 1983 which should be destroyed. This copy includes additional means of identification of components, clarification of usage of "O" rings and additional illustrations.
Beginning April, 1983, all THM 700-R4 transmissions were built with a new 2-4 servo cover and seal. This change provides a tighter fit between the case servo bore and the 2-4 servo cover.
-Case Servo Bore:
The new servo cover "O" ring (P/N 8647351) is identified with a green stripe. This is to distinguish it from the past "O" ring (P/N 8642112) which is still used on the second apply piston (refer to Figure 2, numbers 14 and 21 for correct location of "O" rings).
NOTICE: The past servo "O" ring (P/N 8642112) cannot be used with the new servo cover. If used together, they will leak.
-Case Servo Bore:
-Case Servo Bore:
SERVICE INFORMATION
If a leak is found at the 2-4 servo cover:
1. Remove the 2-4 servo cover and "O" ring seal.
2. Check the case servo bore for sharp edges especially at the recessed slots (see Figure 1).
3. Check the case servo bore for burrs, nicks and 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 P/N 8642979 which will contain a new 2-4 servo cover and "O" ring seal.
5. If it is necessary to replace only the "O" ring seal, use P/N 8647351..
6. When installing the 2-4 servo cover and "O" ring seal, lubricate the seal with petrolatum or equivalent and use care not to cut the seal during installation.