ENGINE OIL LEAK @ OIL PAN SEALING FLANGE. Pontiac Bonneville 1996

SUBJECT: ENGINE OIL LEAK AT OIL PAN SEALING FLANGE (REPLACE OIL PAN AND OIL PAN GASKET)

MODELS: 1995-97 BUICK PARK AVENUE, LESABRE, REGAL, RIVIERA 1995 CHEVROLET LUMINA APV 1995-97 OLDSMOBILE NINETY EIGHT, EIGHTY EIGHT, LSS 1995 OLDSMOBILE SILHOUETTE 1997 OLDSMOBILE REGENCY 1995-97 PONTIAC BONNEVILLE 1996-97 PONTIAC GRAND PRIX 1995 PONTIAC TRANS SPORT WITH 3800 ENGINE (VINS 1, K, L--RPOS L67, L36, L27)

CONDITION:

SOME OWNERS MAY COMMENT ABOUT AN ENGINE OIL LEAK THAT APPEARS TO ORIGINATE FROM THE BOTTOM OF THE ENGINE.

CAUSE:

THE ENGINE OIL PAN SEALING FLANGE MAY HAVE A WAVY SURFACE PREVENTING THE OIL PAN GASKET TO PROPERLY SEAL.

DIAGNOSTICS 1. INSTALL OIL DYE (P/N 12345795) INTO THE CRANKCASE AND WARM THE ENGINE UP TO OPERATING TEMPERATURE BY DRIVING THE VEHICLE A FEW MILES.

2. RAISE THE VEHICLE ON A HOIST WITH THE ENGINE RUNNING AND THOROUGHLY INSPECT FOR OIL LEAKS BY USING A BLACK LIGHT. PAY PARTICULAR ATTENTION TO THE OIL PAN SEALING FLANGE.

IMPORTANT: AN OIL LEAK ORIGINATING ABOVE THE OIL PAN SEALING SURFACE MAY BE DUE TO A CRANKSHAFT REAR OIL SEAL HOUSING GASKET LEAK, AN INTAKE END SEAL LEAK, MAIN BEARING SIDE BOLT LEAK, OR OTHER SOURCES. REPAIR ANY LEAKS ORIGINATING ABOVE THE OIL PAN FIRST BEFORE REPLACING THE OIL PAN.

3. SHUT THE ENGINE OFF AND REMOVE THE FLYWHEEL INSPECTION COVER.

4. USE THE BLACK LIGHT TO CHECK FOR OIL LEAKS IN THE FLYWHEEL AREA. A LEAK IN THIS AREA MAY BE DUE TO A SPLIT GASKET ON THE CRANKSHAFT REAR OIL SEAL HOUSING.

CORRECTION:

1. IF THE LEAK APPEARS TO ORIGINATE AT THE OIL PAN FLANGE, THEN REPLACE THE OIL PAN AND OIL PAN GASKET USING PROCEDURES OUTLINED IN THE APPROPRIATE SERVICE REPAIR MANUAL. THE ENGINE OIL PAN PART NUMBERS LISTED IN THIS BULLETIN SUPERSEDE PREVIOUS PART NUMBERS AND HAVE MUCH IMPROVED SEALING FLANGE FLATNESS.

IMPORTANT: 1. DO NOT USE ANY TYPE OF ADHESIVE ON THE OIL PAN GASKET. 2. THOROUGHLY CLEAN ALL THE OIL PAN BOLTS AND APPLY TWO DROPS OF GM P/N 12345382 (LOCTITE 242 - BLUE) THREAD LOCKER TO THE THREADED END OF THE BOLTS BEFORE INSTALLATION. 3. TORQUE OIL PAN BOLTS TO 14 NM (125 LB IN).

2. IF THE LEAK APPEARS TO ORIGINATE IN THE FLYWHEEL AREA, THEN REMOVE THE CRANKSHAFT REAR OIL SEAL HOUSING AND INSTALL A NEW GASKET AND A NEW CRANKSHAFT REAR OIL SEAL PER BULLETIN 77-61-16.

PARTS INFORMATION FLUORESCENT TRACER DYE, GAS ENGINE OIL (1OZ.) 12345795 GASKET - ENGINE OIL PAN 24502397 PAN - ENGINE OIL (WITH OIL LEVEL SENSOR HOLE) 24507900 PAN - ENGINE OIL (WITHOUT OIL LEVEL SENSOR HOLE) 24507902

WARRANTY INFORMATION FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION DESCRIPTION TIME J1000 PAN AND/OR GASKET, USE PUBLISHED LABOR OIL - REPLACE OPERATION TIME

FIGURES: 0 ATTACHMENTS: 0

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.