A/T - New Auxiliary Accumulator Valve Body/Cover

GMC NUMBER: 87-T-47

GROUP: 7A - Automatic Transmission

DATE: April, 1987

CORPORATE NUMBER:777120R

SUBJECT: NEW AUXILIARY ACCUMULATOR VALVE BODY AND COVER

MODELS: 1987 LIGHT DUTY MODELS WITH THM 700-R4 AUTOMATIC TRANSMISSIONS

Figure 1:

BULLETIN COVERS: (Figure No. 1)

A new auxiliary accumulator valve body (377) and a new cover (371) went into production to prevent the accumulator piston pin from working its way out of the auxiliary valve body. If the accumulator piston pin comes out of either end of the auxiliary valve body the following conditions could occur.

1. Loss of DRIVE
2. Slipping in DRIVE
3. Burned forward and overrun clutches

Figure No. 2 - Transmission I.D. Name Plate:

DATE OF PRODUCTION CHANGE:
(Figure No. 2)

Beginning January 27, 1987 (Julian Date 027) all THM 700-R4 transmissions were produced with an auxiliary accumulator valve body assembly (Figure No. 1) that has a stepped bore at one end of the piston pin and a new cover with an oval instead of a round exhaust hole at the other end of die pin to retain the accumulator piston pin in place.

SERVICE ACTION:

The new auxiliary accumulator valve body (377) and cover (371) can be used on any 1987 THM 700- R4 transmission that has an auxiliary valve body (377).

NOTICE: If the accumulator piston pin has come out of the auxiliary valve body, check for burnt forward and overrun clutches.

SERVICE PARTS INFORMATION:

Part Number Description Models Affected

8663597 Auxiliary MRM, MXM, FAM,
Accumulator MAM, MFM, MMM
Valve Body Assembly

8667036 Auxiliary MCM, MTM, PRM,
Accumulator TAM, TBM, YXM,
Valve Body PCM, TJM, TKM,
Assembly TNM, TRM, TUM,

TXM

8667037 Auxiliary MDM, MHM, MLM,
Accumulator MKM, MPM, MUM,
Valve Body MWM, MZM
Assembly

8667038 Auxiliary TSM, YAM, YDM,
Accumulator YFM, YKM, YLM,
Valve Body YMM, YNM, YPM,
Assembly YSM, TYM, YZM