A/T - Delayed or No Engine Braking in D3

File In Section: 7 - Transmission

Bulletin No.: 87-71-64

Date: May, 1998

Subject:
Delayed or No Engine Braking in D3
(Replace Forward and Coast latch Piston Assemblies)

Models:
1998 Cadillac DeVille, Eldorado, Seville
1998 Oldsmobile Aurora
Built Prior to October 24,1997 - with HYDRA-MATIC 4T80-E Transaxle (RPO MH1) and 4.0L, 4.6L Engine (VINs C, Y, 9 - RPOs L47, LD8, L37)





Condition
(See Figure 1)

Some owners of the above 1998 model transaxles built prior to October 24, 1997 (Julian Date 297) may comment on a no engine braking condition or a several second delay when the shift lever is placed in the D3 position.





Cause
(See Figure 2)

This condition may be the result of coast clutch apply fluid being restricted within the forward clutch piston assembly (807), which is the housing for the coast clutch piston (810). Coast clutch piston apply does not occur due to this fluid restriction.





Correction
(See Figure 3)

To repair this condition, a revised forward clutch piston assembly (807) must be installed. The revision to the forward clutch piston is an additional machining operation on the coast clutch piston side that appears as a shiny surface at the center hub of the forward clutch piston.

Transaxles built prior to October 24, 1997 (Julian Date 297) will be serviced with a service kit P/N 24213271 that contains both the new forward clutch piston (807) and the coast clutch piston (810). Both pistons must be replaced together to ensure that coast clutch fluid is no longer restricted.

Service Information

Road test the vehicle and verify that it has no engine braking in D3 as described under "Condition". Replace the forward clutch piston assembly. Refer to the Unit Repair Section of the Service Manual for the proper procedure.

Parts Information

Part Number Description

24213271 Piston-Kit

Parts are currently available at GMSPO.

Warranty Information

For vehicles repaired under warranty, use table:

Labor Operation Description Labor Time

K7572 Forward/Coast - Use published
R & R Replace labor operation time