SMU - SECTION 6A - ENGINE MECHANICAL - TIMING CHAIN

SUBJECT: SERVICE MANUAL UPDATE-SECTION 6A-ENGINE MECHANICAL- TIMING CHAIN TENSIONER SERVICE PROCEDURE

MODELS: 1997 CHEVROLET CAVALIER, MALIBU 1997 OLDSMOBILE ACHIEVA 1997 PONTIAC SUNFIRE, GRAND AM 1997 BUICK SKYLARK WITH 2.4L ENGINE (VIN T--RPO LD9)

THIS BULLETIN IS BEING ISSUED TO UPDATE THE SERVICE PROCEDURES FOR THE TIMING CHAIN TENSIONER ON LD9 ENGINES BUILT AFTER SEPTEMBER 29, 1996. THESE ENGINES HAVE A NEW TWO-PIECE TIMING CHAIN TENSIONER.

IMPORTANT: THE NEW TWO-PIECE TIMING CHAIN TENSIONER IS NOT INTERCHANGEABLE WITH THE PREVIOUS VERSION. DO NOT ATTEMPT TO REPLACE THE ONE-PIECE TIMING CHAIN TENSIONER WITH THE TWO PIECE DESIGN.

TIMING CHAIN, SPROCKETS, AND TENSIONER REMOVAL

NOTICE: THE TIMING CHAIN ON THE LD9 (VIN T) TWIN CAM ENGINE IS NOT TO BE REPLACED WITH THE TIMING CHAIN FROM ANY OTHER MODEL YEAR. THE TIMING CHAIN SPROCKETS ARE DIFFERENT ON THE TWIN CAM ENGINE AND THE SHAPE OF THE LINKS MATCHES THE SPROCKETS. ENGINE DAMAGE MAY RESULT IF THE WRONG TIMING CHAIN IS USED. THE TIMING CHAIN AND THE CRANKSHAFT SPROCKET MUST BE MARKED SO THAT THEY ARE REINSTALLED WITH THE SAME SIDE FACING OUT AT THE TIME OF REASSEMBLY.

PROCEDURE:

IMPORTANT: READ THE ENTIRE PROCEDURE BEFORE REMOVING THE TIMING CHAIN.

1. MARK THE TIMING CHAIN AND THE CRANKSHAFT SPROCKET OUTER SURFACES FOR REASSEMBLY. ENSURE THAT THIS IS DONE IN ORDER TO PREVENT NOISE AND INCREASED WEAR ON THE CHAIN. 2. REMOVE THE TIMING CHAIN GUIDES. (GRAPHIC 62882) 3. REMOVE THE TIMING CHAIN TENSIONER BLOCK AND TENSIONER. 4. REMOVE THE TIMING CHAIN TENSIONER SHOE FROM THE STUD. USE A SMALL LOCKING RING PLIER TO ENGAGE THE HOLE IN THE LOCKING TAB TO REMOVE THE SHOE FROM THE STUD. (GRAPHIC 62881) 5. REMOVE THE TIMING CHAIN. (GRAPHIC 33625) 6. INSPECT THE PARTS FOR WEAR, REPLACE THEM AS REQUIRED. 7. REPLACE THE TIMING CHAIN SHOE OR THE GUIDES IF THE SCORING EXCEEDS 1.12 MM (0.045 IN). 8. REMOVE THE TIMING CHAIN TENSIONER PLUNGER FROM THE TENSIONER BODY. WHEN THE TIMING CHAIN TENSIONER BODY WAS REMOVED FROM THE HOUSING, THE PLUNGER SHOULD HAVE EXTENDED TO FULL LENGTH EXPOSING THE DRAIN HOLES. IF THE PLUNGER DID NOT EXTEND, REPLACE THE TENSIONER ASSEMBLY.

9. PLACE THE TENSIONER PLUNGER ON ITS SIDE ON A SHOP RAG TO ALLOW THE OIL TO DRAIN FROM THE INSIDE OF THE TENSIONER.

TIMING CHAIN, SPROCKETS, AND TENSIONER INSTALLATION

TOOLS REQUIRED J39579 CAMSHAFT SPROCKET WRENCH J36008-A CAMSHAFT SPROCKET ALIGNMENT PINS IMPORTANT: ENSURE THAT THE CAMSHAFT SPROCKET ALIGNMENT PINS ARE IN THE CYLINDER BLOCK AND THE TIMING CHAIN HOUSING, PRIOR TO INSTALLING THE TIMING CHAIN HOUSING. THE CAMSHAFT SPROCKET ALIGNMENT PINS ENSURE PROPER CHAIN HOUSING AND FRONT COVER LOCATION FOR CORRECT FRONT OIL- SEAL-TO-CRANKSHAFT ALIGNMENT.

1. INSTALL J36008-A THROUGH HOLES IN THE CAMSHAFT SPROCKETS AND INTO HOLES IN THE TIMING CHAIN HOUSING. THIS WILL POSITION THE CAMSHAFT FOR CORRECT TIMING. (GRAPHIC 62885) 2. USE THE FOLLOWING STEPS IF THE CAMSHAFTS ARE OUT OF POSITION AND MUST BE ROTATED MORE THAN 1/8 TURN TO INSTALL THE ALIGNMENT DOWEL PINS: NOTICE: FAILURE TO FOLLOW THIS PROCEDURE COULD RESULT IN SEVERE ENGINE DAMAGE. 2.1 THE CRANKSHAFT MUST BE ROTATED 90 DEGREES CLOCKWISE OFF OF TDC TO GIVE THE VALVES ADEQUATE CLEARANCE TO OPEN. 2.2 ONCE THE CAMSHAFTS ARE IN POSITION AND THE J36008-A CAMSHAFT SPROCKET ALIGNMENT PINS ARE INSTALLED, ROTATE THE CRANKSHAFT COUNTER-CLOCKWISE BACK TO TDC. NOTICE: DO NOT ROTATE THE CRANKSHAFT CLOCKWISE TO TDC. VALVE OR PISTON DAMAGE COULD OCCUR. IMPORTANT: THE TIMING CHAIN AND CRANKSHAFT SPROCKET MUST BE PUT ON IN A SPECIFIC DIRECTION FOR CHAIN NOISE AND WEAR CONSIDERATIONS. THE SURFACES THAT WERE MARKED DURING REMOVAL SHOULD BE SHOWING WHEN THE CHAIN AND CRANKSHAFT SPROCKET ARE INSTALLED. 3. INSTALL THE TIMING CHAIN OVER THE EXHAUST CAMSHAFT SPROCKET AROUND THE COOLANT PUMP SPROCKET AND AROUND THE CRANKSHAFT SPROCKET. 4. REMOVE THE J36008-A CAMSHAFT SPROCKET ALIGNMENT PIN FROM THE INTAKE CAMSHAFT. USE J 39579 IN ORDER TO ROTATE THE INTAKE CAMSHAFT SPROCKET COUNTER-CLOCKWISE ENOUGH TO ALLOW THE TIMING CHAIN TO SLIDE OVER THE INTAKE CAMSHAFT SPROCKET. 5. RELEASE J39579. THE LENGTH OF THE CHAIN BETWEEN THE TWO CAMSHAFT SPROCKETS WILL TIGHTEN. 6. IF PROPERLY TIMED, THE J36008-A CAMSHAFT SPROCKET ALIGNMENT PIN WILL SLIDE IN EASILY. IF THE DOWEL PIN DOES NOT FULLY INDEX, THE CAMSHAFTS ARE NOT TIMED CORRECTLY AND THE PROCEDURE MUST BE REPEATED. 7. LEAVE THE ALIGNMENT DOWEL PINS INSTALLED. 8. THE KEYWAY ON THE CRANKSHAFT AND THE MARK ON THE CYLINDER BLOCK SHOULD BE ALIGNED, WITH THE SLACK REMOVED FROM THE CHAIN BETWEEN THE INTAKE CAMSHAFT SPROCKET AND THE CRANKSHAFT SPROCKET. IF THE MARK AND THE KEYWAY ARE NOT ALIGNED, MOVE THE CHAIN ONE TOOTH FORWARD OR REARWARD; REMOVE THE SLACK AND RECHECK THE MARKS. (GRAPHIC 62885) 9. USE THE FOLLOWING STEPS IN ORDER TO RELOAD THE TENSIONER ASSEMBLY TO ITS ZERO POSITION: 9.1. ASSEMBLE THE TENSIONER PLUNGER AND THE TENSIONER BODY. 9.2. WITH THE TENSIONER PLUNGER FULLY EXTENDED, TURN THE TENSIONER AND TENSIONER BODY UPSIDE DOWN ON A BENCH OR OTHER FLAT SURFACE. A METAL WORKBENCH IS BEST FOR THIS. 9.3. WITH THE PLUNGER FACE AGAINST THE WORKBENCH, PRESS FIRMLY ON THE BOTTOM OF THE TENSIONER BODY, COMPRESS THE TENSIONER PLUNGER UNTIL IT IS SEATED FLUSH IN THE TENSIONER. (GRAPHIC 62880) 10. INSTALL THE TENSIONER BODY AND PLUNGER TO THE CHAIN HOUSING. 11. INSTALL THE TIMING CHAIN TENSIONER SHOE ON THE STUD. APPLY HAND PRESSURE TO THE TIMING CHAIN TENSIONER SHOE UNTIL THE LOCKING TAB SEATS IN THE GROOVE IN THE STUD. 12. TIGHTEN THE TIMING CHAIN TENSIONER BODY BOLTS. DO NOT OVER-TIGHTEN.

TIGHTEN TIGHTEN THE BOLTS TO 10 NM (89 LB IN.) REFER TO FASTENER NOTICE IN GENERAL INFORMATION

13. REMOVE J 36008-A FROM THE CAMSHAFT SPROCKETS.

NOTICE: WHEN RELEASING THE TIMING CHAIN TENSIONER PLUNGER, USE CARE NOT TO SCRATCH OR GOUGE THE FACE OF THE TIMING CHAIN TENSIONER PLUNGER. 14. USING A FLAT-BLADE SCREWDRIVER OR A SIMILAR TOOL, PRESS AGAINST THE FACE OF TIMING CHAIN TENSIONER PLUNGER. THE PLUNGER WILL RELEASE AGAINST THE BACK OF THE TIMING CHAIN TENSIONER SHOE. (GRAPHIC 62883) NOTICE: THE TIMING CHAIN ON THE LD9 (VIN T) TWIN CAM ENGINE IS NOT TO BE REPLACED WITH THE TIMING CHAIN FROM ANY OTHER MODEL YEAR. THE TIMING SPROCKETS ARE DIFFERENT ON THE TWIN CAM ENGINE AND THE SHAPE OF THE LINKS MATCHES THE SPROCKETS. ENGINE DAMAGE MAY RESULT IF THE WRONG TIMING CHAIN IS USED. THE TIMING CHAIN AND THE CRANKSHAFT SPROCKET MUST BE MARKED SO THAT THEY ARE REINSTALLED WITH THE SAME SIDE FACING OUT AT THE TIME OF REASSEMBLY.

15. ROTATE THE CRANKSHAFT CLOCKWISE TWO FULL ROTATIONS. ALIGN THE CRANKSHAFT KEYWAY WITH THE MARK ON THE CYLINDER BLOCK AND REINSTALL THE J36008-A CAMSHAFT SPROCKET ALIGNMENT PINS. THE ALIGNMENT PINS WILL SLIDE IN EASILY IF THE ENGINE IS TIMED CORRECTLY. 16. INSTALL THE TIMING CHAIN GUIDES. (GRAPHIC 62882)

FIGURES: 6 ATTACHMENTS: 0

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