OIL LEAK AT FRONT CRANK SEAL NEW FRONT CRANKSHAFT SEAL

Subject: OIL LEAK AT FRONT CRANKSHAFT SEAL

Model and Year: 1990 C/K/G/P/M/L TRUCKS AND 1991 S/T TRUCKS WITH 4.3L (VIN CODE Z) ENGINE

TO: ALL CHEVROLET DEALERS

CONDITION: Some of the above trucks may exhibit an oil leak at the front of the engine coming from between the crankshaft seal and timing chain cover.

CAUSE: This condition may be caused by inadequate retention of the crankshaft seal in the timing chain cover.

CORRECTION: To correct this condition, a new front crankshaft seal must be installed per the following instructions.

1. Remove old seal per Service Manual section 6A.

2. Thoroughly clean the hole in the timing cover and metal outside diameter of the new seal. Wipe both surfaces using a clean rag damp with brake cleaner solvent, isopropyl (rubbing) alcohol or Loctite (R) 755 cleaning solvent.

IMPORTANT: Do not use gasoline, diesel fuel, kerosene, or solvents which may leave a residue or deteriorate the seal.

3. Inspect cover hole for any damage. If damage is apparent, replace cover assembly. If there is no damage, continue to step 4.

4. Apply a bead of Loctite (R) 680 retaining compound around the metal outside diameter of the new seal and install the seal per the service manual using tool J-35468.

IMPORTANT: Do not use RTV in place of Loctite (R) 680 to install the new seal.

SERVICE PARTS:

Description P/N ---------------------------- ----------- Seal, Crankshaft Front 10111769

Loctite (R) 680 Retaining Compound Obtain from local Loctite Distributor

Loctite (R) 755 Cleaning Solvent Obtain from local Loctite Distributor

Parts are currently available from GMSPO.

"We believe this source and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from this firm or for any such items which may be available from other sources."

Use Labor Operation Number: J0750

Labor Time: S/T .7 hrs P .9 hr M/L/C/K/G .6 hrs

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.