FLUID LEAK FROM HOUSING VENT INSTALL REMOTE VENT

MODELS: 1988 C/K TRUCKS WITH HM-117 MANUAL TRANSMISSION (RPO M20)

A 1988 C/K truck with a HM-117 manual transmission may develop a fluid leak out the vent.

NOTE: Figure No. 1 - Transmission Identification Information.

SERVICE ACTION:

The addition of a remote vent will prevent fluid from leaking out the cover vent. To repair, perform the following:

1. Remove transmission (also transfer case if applicable).

o If the model code on the I.D. tag is GGD or GGG refer to GMC campaign 88-C-03 or Chevrolet campaign 88-C-02.

NOTE: PERFORMING THE CAMPAIGN WILL NOT CORRECT THE FLUID LEAK OUT THE VENT. The remote vent MUST be added.

2. Remove existing vent.

3. Install a vent sleeve and pipe assembly in the vent tube hole (Figure No. 2).

-Position the end of the fitting toward clutch housing.

-Install with dull wide blade screwdriver.

4. Attach 660 mm (2'6") of 8.00 mm (5/16") I.D. hose to the pipe assembly and secure it with a worm type clamp.

5. Reinstall transmission (also transfer case if applicable).

6. Install a NEW vent assembly in the end of the hose.

7. Secure the hose to the large wire harness underhood on the passenger side of the engine cowl with a plastic tie wrap (Figure No.3).

SERVICE PARTS INFORMATION

PART NUMBER PART NAME ------ --------- 8652580 Vent Sleeve and Pipe Assembly 9439104 5/16" I.D. Hose X 660 mm (2'6") 8640496 Vent Assembly 3816659 Plastic Tie Wrap 25518880 Clamp, worm type, 1/4" - 5/8"

SERVICE MANUAL REFERENCE:

Refer to transmission replacement in the on- vehicle service section of the appropriate service manual for procedures.

SERVICE NOTES:

1. Model designation YAY is the updated version of GGD and YBY is the updated version of GGG.

2. The 117 mm will now be referred to as the HM-117.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.