LOSS OF OIL PRESSURE/TURBO FAILURE INSPECT/REPL. OIL PLUG

SUBJECT: LOSS OF ENGINE OIL PRESSURE OR TURBOCHARGER FAILURE (INSPECT/REPLACE OIL GALLERY PLUGS)

MODELS: 1994 CHEVROLET AND GMC C/K, G AND P TRUCKS WITH 6.5L DIESEL ENGINE (VINS F, P, S, Y - RPOS L65, L49, L56, L57)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * NOTE: THIS BULLETIN ADDRESSES ENGINE SERVICE PROHIBITED IN THE * * ENGINE EXCHANGE BULLETIN 376115A. IF, HOWEVER, THERE IS * * NO MAJOR ENGINE DAMAGE AND THE OIL GALLERY CUP PLUGS HAVE * * FAILED, THESE INSTRUCTIONS TAKE PRIORITY OVER THOSE FOUND * * IN BULLETIN 376115A. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

CONDITION:

SOME OWNERS MAY EXPERIENCE A LOSS OF OR LOWER OIL PRESSURE IF THE LEFT OIL GALLERY CUP PLUG FALLS OUT, OR TURBOCHARGER FAILURE IN ADDITION TO LOSS OF OIL PRESSURE IF THE RIGHT OIL GALLERY CUP PLUG FALLS OUT.

CAUSE:

A SMALL NUMBER OF PRODUCTION ENGINES BUILT PRIOR TO APRIL 1, 1994, MAY HAVE HAD TOO MUCH CHAMFER ON OIL GALLERY PLUG BORES. AS A RESULT, THE CUP PLUG DID NOT FIT PROPERLY IN THE CHAMFERED AREA AND COULD POP OUT.

CORRECTION:

IF THE VEHICLE HAS LOWER OIL PRESSURE (SPECS: 10 PSI AT IDLE - HOT; 40 TO 45 PSI AT 2000 RPM) AND IT CAN BE VERIFIED USING A MANUAL GAUGE, REMOVE THE FRONT COVER AND INSPECT THE OIL GALLERY CUP PLUGS. IF THE LEFT PLUG HAS FALLEN OUT, INSPECT THE ENGINE'S MAIN AND ROD BEARINGS. THE FRONT ROD BEARING (#1) AND FRONT MAIN BEARING (#1) WILL BE THE FIRST TO FAIL. IF INSPECTION INDICATES THE BEARINGS ARE NOT DAMAGED, REPLACE BOTH OIL GALLERY PLUGS. IF INSPECTION FINDS DAMAGE TO THE BEARINGS, REPLACE THE ENGINE. SEE PARTS AND INSTALLATION INFORMATION FOR PROPER PROCEDURES.

IF THE TURBOCHARGER FAILED BECAUSE OF LOSS OF OIL FEED, REMOVE THE FRONT COVER AND INSPECT THE RIGHT OIL GALLERY CUP PLUG. IF THE RIGHT CUP PLUG HAS FALLEN OUT, REPLACE BOTH OIL GALLERY CUP PLUGS. WHEN THE TURBOCHARGER HAS FAILED, INSPECT THE INTAKE SYSTEM TO THE ENGINE AND OIL RETURN TUBE FOR ANY METAL SHAVINGS. IF METAL SHAVINGS HAVE ENTERED THE ENGINE, REPLACE THE ENGINE. SEE PARTS AND INSTALLATION INFORMATION FOR PROPER REPAIR PROCEDURES.

INSTRUCTION:

AFTER INSPECTING THE ENGINE, VERIFYING THERE IS NO FURTHER DAMAGE AND THE CUP PLUGS ONLY NEED TO BE REPLACED, PERFORM THE FOLLOWING:

REMOVE THE ENGINE FRONT COVER AND TIMING GEARS TO REPLACE THE CUP PLUGS. FOLLOW INSTRUCTIONS IN THE SERVICE MANUAL FOR PROPER PROCEDURES.

**NOTICE: IF THE TIMING CHAIN, TIMING GEARS, FRONT COVER, CRANKSHAFT OR OTHER COMPONENT(S) AFFECTING TIMING ARE REPLACED, IT WILL BE NECESSARY TO REPROGRAM TDC OFFSET INTO THE PCM. REFER TO BULLETIN 476508 (VINS F, P, S - RPOS L65, L49, L56 ONLY). FOR VIN Y - RPO L57, FOLLOW SERVICE MANUAL PROCEDURE.**

1. REMOVE BOTH PLUGS FROM OIL GALLERY; SEE FIGURE 1 FOR LOCATION OF PLUGS. 2. CLEAN BORES FOR PLUGS FROM ANY OIL AND DRY. 3. USE P/N 12345493 ON NEW PLUGS FOLLOWING MANUFACTURER'S DIRECTIONS. 4. INSTALL NEW CUP PLUGS, P/N 10105918, TO A DEPTH THAT THE TOP LIP OF PLUG IS AT BOTTOM OF CHAMFER BUT NOT TOO DEEP TO BLOCK OIL FEED PASSAGES (SEE FIGURE 2). 5. IF PLUG(S) HAVE FALLEN OUT, LOCATE AND REMOVE THEM; PLUGS ARE PROBABLY IN THE OIL PAN.

PART INFORMATION:

DESCRIPTION PART NUMBER QUANTITY ----------- ----------- -------- CUP PLUGS 10105918 2 SEALER 12345493 1

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO. THE NEW ENGINES WILL COME WITH NEW CUP PLUGS (P/N 10105918) AND CHAMFER CHANGE.

WARRANTY INFORMATION:

LABOR OPERATION: J0820 - TIMING CHAIN REPLACEMENT USE PUBLISHED LABOR TIME PLUS 0.3 HOUR FOR OIL CUP PLUG REPLACEMENT.

J1150 - BEARING INSPECTION USE PUBLISHED LABOR OPERATION TIME.

FIGURES: 2

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.

COPYRIGHT 1994. GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.