A/T - Intermittent Delayed Engagement In Drive & Reverse

9232chevy01

Number: 92-120A-7A

Section: 7A

Date: MARCH 1992

Corporate Bulletin No.: 277116

ASE No.: A2


Subject:
INTERMITTENT DELAYED ENGAGEMENT IN DRIVE & REVERSE


Model and Year:
1991-92 LUMINA AND 1991-92 LUMINA (APV) WITH 4T60 AND 4T60-E AUTOMATIC TRANSMISSION


TRANSAXLE APPLICATIONS:
1991-92 HYDRA-MATIC 4T60 (ME9)
1991-92 HYDRA-MATIC 4T60-E (M13)

TRANSAXLE MODELS:
All


SUBJECT:
Intermittent Delayed Engagement in Drive and Reverse after "Cold" Soak Overnight (Replace input clutch outer piston seal)

VEHICLE APPLICATIONS:
W-Car U-Van





CONDITION:
(Figure 1) Some vehicles equipped with a HYDRA-MATIC 4T60 (RPO ME9) or HYDRA-MATIC 4T60-E (RPO M13) transaxle built before November 1, 1991 may experience an intermittent delayed engagement in drive and/or reverse after a "cold" soak overnight. The condition may gradually become more noticeable as vehicle mileage increases, and as ambient temperature decreases.

NOTE:
Once transaxle is brought to operating temperature, the condition may not be able to be reproduced until a "cold" soak overnight is performed.





CAUSE:
(Figure 2)
The above condition may be caused by a rolled or cut input clutch outer piston seal (635).

NOTE:
An air check of the input clutch outer piston seal could be misleading, due to the position of the seal, and should not be used as a factor to determine proper function. Also, the seal may look good during visual inspection but should be replaced if the above condition is present. The seal may have rolled back into the proper position during disassembly

The following is a list of items which may also affect the engagement time into drive and/or reverse:

4T60 (RPO ME9)
- Fluid level low
- Cooler checkball (569) not seating properly allowing converter drain back
- Reverse servo assembly seal (547) cut or damaged
- 1-2 servo, assembly seal (557) cut or damaged
- Seal assembly 1-2 servo pipe (383) cut or damaged
- Pipe, 1-2 servo apply (136) split or damaged
- Retainer and ball assembly (625) damaged (in the input shaft and housing assembly)


4T60-E (M13)
- Fluid level low
- Cooler checkball (28) not seating properly allowing converter drain back
- Reverse servo assembly seal (43) cut or damaged
- Forward servo assembly seal (18) damaged or cut
- 2-1 servo seal (105) damaged or mislocated
- Retainer and ball assembly (633) damaged (in the input shaft and housing assembly)

CORRECTION:
To repair this condition, replace the input clutch outer piston seal. Refer to the appropriate Service Manual under "Automatic Transaxle Unit Repair" for the proper disassembly and assembly procedure.

LABOR TIME INFORMATION:
Labor time should be charged under Operation Number K7536, for "Input Clutch Piston Outer SealReplace" from the appropriate LABOR TIME GUIDE manual.