A/T - Leaks From the Oil Pump Body
86chevy14CORPORATE NUMBER: 677119R NUMBER: 86-T-124
GROUP: 7A - Automatic Transmission
IMPORTANT - All Service Personnel Should Read DATE: November, 1986
SUBJECT: FLUID LEAKS FROM THE OIL PUMP BODY
MODELS: 1984-86 LIGHT DUTY MODELS WITH 700-R4 AUTOMATIC TRANSMISSIONS
Some 1984 through 1986 THM 700-R4 transmissions may exhibit fluid leaks from the oil pump body caused by walk-out of the pump body bushing and helix seal assembly. Several changes have been made to this area.
Figure 1 - THM 700-R4 Transmission Identification Information:
Figure 2 - OIL PUMP BODY ASSEMBLY:
Beginning October 10, 1985 (Julian Date 283, see Figure No. 1) a new front pump helix seal assembly with a 270 degree lip was introduced. In addition, all THM 700-R4 transmission models incorporated a machine step (smaller bore diameter) in the oil pump effective January 6, 1986 (Julian Date 006) as shown in Figure No. 2. The latest change, effective February 11, 1986 (Julian Date 042), a new front pump seal retainer was added to eliminate walk-out of the pump body bushing and helix seal assembly.
SERVICE ACTION:
To service a 1984 (after Julian Date 180) through 1986 THM 700-R4 transmission that exhibits the subject condition, replace the pump body assembly. The new seal assembly and retainer are included with the pump body assembly or are available separately.
Figure 2 - OIL PUMP BODY ASSEMBLY:
SERVICE PARTS INFORMATION: (Figure No. 2)
8649950 Pump Body Assembly (including bushing)
8648394 Seal Assembly
8654491 Seal Retainer
SERVICE MANUAL REFERENCE:
Refer to Section 7A of the appropriate light duty model service manual for Oil Pump Assembly removal procedures.
Figure 3 - BUSHING INSTALLATION:
SERVICE NOTES: (Figure No. 3)
The pump body bushing is included in the above pump body assembly, however, the procedure for installing a service bushing has been changed. Because of the stepped bore in the oil pump body, the bushing is now installed from the rear (using Kent-Moore tool J 34196-12) and fits tight against the step in the bore.