SERVICE MANUAL UPDATE-REVISED CAM GEAR REPLACEMENT PROCEDURE

SERVICE MANUAL UPDATE - REVISED C M GEAR REPLACEMENT SERVICE PROCEDURE (NEW PROCEDURE)

MODELS AFFECTED: 1982-88 CENTURYS WITH 2.5L L-4 ENGINES (VIN CODE R) --------------- 1985-87 SOMERSETS WITH 2.5L L-4 ENGINES (VIN CODE U) 1986-88 SKYLARKS WITH 2.5L L-4 ENGINES (VIN CODE U)

SERVICE MANUAL UPDATE

NOTICE: THIS BULLETIN SUPERSEDES CURRENT AND PAST SERVICE MANUAL PROCEDURES.

A set of revised service procedures had been developed for replacement of camshaft timing gears. The revised methods do not require the complete removal of the engine from the vehicle. Cam gear replacement is generally accomplished by partially lowering the engine/cradle assembly to gain access to the cam gear.

This bulletin contains two separate and complete procedures for servicing cam gears on A, and N cars.

NOTICE: See appropriate Service Manual Section for fastener torque specifications.

A CAR SERVICE PROCEDURE

Tools Required:

J28467-A Engine Support Fixture J24420-B Cam Gear Removal Tool J25O33-B Cam Gear Installation Tool J34995 Crankshaft Front Cover Oil Seal Installer J8001 Universal Dial Indicator w/Magnetic Base

Remove or Disconnect

1. Negative battery cable. 2. Drain coolant. 3. Belt tensioner and belt, or drive belts, as applicable. 4. Upper engine torque strut. 5. Timing pointer plate (as applicable). 6. Both forward hood bumpers. 7. Install engine support fixture - J28467-A per Service Manual. 8. Raise Vehicle. 9. Both front wheels. 10. Drain engine oil (remove oil filter). 11. Steering shaft pinch bolt at steering gear. 12. Right front lower ball joint. 13. Right front brakeline-to-body bracket. 14. Right front wheelhouse engine splash shield. 15. Flywheel/flexplate cover. 16. Crankshaft pulley (have assistant hold flywheel). 17. Frame (cradle) bolts and insulators (4). 18. Lower vehicle. 19. Timing gear cover bolts (8). 20. Lower the passenger side of the cradle/powertrain assembly 4 inches with support fixture may require lowering of driver's side). 21. Raise vehicle. 22. Timing gear cover - do not distort.

Clean

- Timing gear cover and engine sealing surfaces.

23. Align crankshaft/camshaft timing marks on gears. 24. Drill and tap hole on the camshaft centerline (8mm drill, 1/2 inch deep).

CAUTION:

WEAR SAFETY GLASSES TO AVOID EYE DAMAGE

USE CARE WHEN DRILLING AND TAPPING CAM GEAR TO AVOID DAMAGE TO THE CANSHAFT.

IMPORTANT: COVER OIL PAN OPENING WITH RAGS TO PREVENT CHIPS FROM FALLING INTO PAN.

25. Tap the 8mm hole with a 3/8-16-NC bottoming tap.

IMPORTANT! AVOID BUILD-UP OF CHIPS. BACK OUT THE TAP EVERY FEW TURNS AND REMOVE CHIPS.

26. Center punch and drill (2) 3mm pilot holes in the metal hub of the cam gear (180 degrees apart).

IMPORTANT! USE CARE TO AVOID DRILL MANDER THAT COULD DAMAGE CAMSHAFT.

27. Enlarge pilot holes with 5.5mm drill; 1/4 inch deep. 28. Tap 5.5mm holes with 1/4-28-NF bottoming tap. 29. Drill a hole no larger than 1mm (.040 in.) in the front oil gallery plug. This provides improved lubrication to the timing gears.

Clean

- Oil pan of debris.

30. Cam gear with J24420-B - do not move cam or crank.

Inspect

- Thrust plate for scuffing and/or grooving. If evident, install new thrust plate, spacer ring, and key. Thrust plate-to-block bolts torque - 10 Nm.(90 lb. in.).

IMPORTANT: LUBRICATE FRONT THRUST PLATE SURFACE WITH CLEAN ENGINE OIL.

Install or Connect

1. Cam gear using J25033-B - align timing marks.

Measure

Camshaft end play using dial indicator - J8001 or equivalent. Push cam gear onto camshaft until camshaft end play is in the range of .0015 in. to .0050 in. (.04mm to .13MM).

2. J34995 into front cover - lubricate seal lip with clean engine oil. 3. Apply RTV sealant to timing gear cover sealing surfaces. 4. Timing gear cover to engine. 5. Brakeline bracket to frame. 6. Crank pulley and bolt. 7. Flywheel/flexplate- cover and bolts. 8. Lower vehicle. 9. Raise frame assembly with support fixture. 10. Install (4) frame (cradle) bolts finger tight. 11. Remove engine fixture. 12. Raise vehicle. 13. Cradle bolts. 14. Lower ball joint; use new pinch bolt. 15. Steering shaft pinch bolt. 16. Engine splash shield. 17. Both front wheels. 18. Lower vehicle 19. Front hood bumpers. 20. Engine torque strut. 21. Tensioner - as applicable.

Clean

- Tensioner and block sealing surfaces. Do not remove LIM ring. Apply RTV around LIM ring.

22. Timing pointer plate (as applicable). 23. Accessory drive belt(s). 24. Engine oil (replace oil filter). 25. Coolant. 26. Negative battery cable. 27. Check front end toe-end and adjust if necesssary.

Inspect

- For oil and coolant leaks with engine running at operating temperature. - For proper completion of repairs.

Labor Operation Number: J0840

For 1987-88

Labor Time: 3.9 Hours To Replace Crankshaft Gear - Add .1 Hours Locking Wheel Covers and/or Nuts - Add .2 Hours

For 1982-86

Labor Time: 4.2 Hours A/C - Add: .1 Hours To Replace Crankshaft Gear - Add: .1 Hour Locking Wheel Covers and/or Nuts - Add: .2 Hour

N-CAR SERVICE PROCEDURE

Tools Required:

J28467-A Engine Support Fixture (with long hooks) J24420-B Cam Gear Removal Tool J25033-B Cam Gear Installation Tool J34995 Crankshaft Front Cover Oil Seal Installer J8001 Universal Dial Indicator w/Magnetic Base

Remove or Disconnect

1. Negative battery cable. 2. Accessory drive belts. 3. Power steering pump mount bolts - lay pump aside. 4. Drain coolant (1985-86 only). 5. Timing pointer plate (1985-86 only). 6. Body ground strap. 7. Front end sheet metal diagonal brace (R.H.). 8. Install engine support fixture - J28467-A per Service Manual. 9. Upper front engine mount to body bolts (2). 10. Raise vehicle. 11. Right front wheel. 12. Right front brakeline-to-body bracket. 13. Right front wheelhouse engine splash shield. 14. Flywheel/flexplate cover. 15. Crankshaft pulley (have assistant hold flywheel). 16. Rear engine mount to bracket nuts and mount thru bolts. 17. Rear transaxle strut - automatic transaxle only (as applicable). 18. Lower front engine mount to body bolt (leave mount attached to engine). 19. Retaining bolts from right side0140 front suspension support (6). 20. Retaining bolts from left side front suspension support (6). 21. Drain engine oil (remove oil filter). 22. Lower vehicle. 23. Transaxle mount thru bolt. 24. Lower engine/transaxle assembly with engine support fixture. 25. Raise vehicle. 26. Timing gear cover- do not distort.

Clean

- Timing gear cover and engine sealing surfaces.

27. Align crankshaft/camshaft timing marks on gears. 28. Drill and tap hole on the camshaft centerline (8mm drill, 1/2 inch deep).

CAUTION:

WEAR SAFETY GLASSES TO AVOID EYE DAMAGE.

USE CARE WHEN DRILLING AND TAPPING CAM GEAR TO AVOID DAMAGE TO THE CAMSHAFT.

IMPORTANT: COVER OIL PAN OPENING WITH RAGS TO PREVENT CHIPS FROM FALLING INTO PAN.

29. Tap the 8mm hole with a 3/8-16-NC bottoming tap.

IMPORTANT: AVOID BUILD-UP OF CHIPS. BACK OUT THE TAP EVERY FEW TURNS AND REMOVE CHIPS.

30. Center punch and drill (2) 3mm pilot holes in the metal hub of the cam gear (180 degrees apart).

IMPORTANT: USE CARE TO AVOID DRILL WANDER THAT COULD DAMAGE CAMSHAFT.

31. Enlarge pilot holes with 5.5 m drill; 1/4 inch deep. 32. Tap 5.5mm holes with 1/4-28-NF bottoming tap. 33. Drill a hole no larger than 1 m (.040 in.) in the front oil gallery plug. This provides improved lubrication to the timing gears.

Clean

- Oil pan of debris.

34. Cam gear with J24420-B - do not move cam or crank.

Inspect

- Thrust plate for scuffing and/or grooving. If evident, install new thrust late, spacer ring, and key. Thrust plate-to-block bolts torque 10 N.m 90 lbs. in.).

IMPORTANT: LUBRICATE FRONT THRUST PLATE SURFACE WITH CLEAN ENGINE OIL.

Install or Connect

1. Cam gear using J25033-B - align timing marks.

Measure

- Camshaft end play using dial indicator - J8001 or equivalent. Push cam gear onto camshaft until camshaft until camshaft end play is in the range of .0015 in. to .0050 in. (.04 m to .13mm).

2. J34995 into front cover - lubricate seal lip with clean engine oil. 3. Apply RTV sealant to timing gear cover sealing surfaces. 4. Timing gear cover to engine. 5. Lower vehicle. 6. Raise engine assembly with support fixture. 7. Thru bolt in rear transaxle mount. 8. Retaining bolts (2) in front engine mount. 9. Raise vehicle 10. Retaining nuts (2) and thru bolts (2) in right front engine mount. 11. Retaining bolt (1) in left front engine mount. 12. Place axle stand under right front suspension support, raise into position and fasten with retaining bolts (6). 13. Place axle stand under left front suspension support, raise into position and fasten with retaining bolts. 14. Crankshaft pulley and bolt (w/assistant). 15. Flywheel/flexplate cover and bolts. 16. Engine splash shield. 17. Brakeline-to-body bracket. 18. Right front wheel. 19. Lower vehicle. 20. Transaxle bracket to transaxle mount long bolt. 21. Remove engine support fixture. 22. Timing pointer plate (1985-86 only). 23. Engine coolant (1985-86 only). 24. Engine oil (replace oil filter). 25. Power steering pump mount bolts to engine. 26. Accessory drive belts. 27. Front end sheet metal diagonal brace (R.H.). 28. Body ground strap. 29. Negative battery cable. 30. Check front end toe and adjust, if necessary.

Inspect

- For oil and coolant leaks with engine running at operating temperature. - For proper completion of repairs.

Labor Operation Number: J0840

For 1987-88

Labor Time: 4.7 Hours A/C - Add: .2 Hours To Replace Crankshaft Gear - Add: .1 Hour Automatic Transmission (1987 only) - Add: .1 Hour Locking Wheel Covers and/or Nuts - Add: .1 Hour

For 1985-86

Labor Time: 5.1 Hours A/C - Add: .2 Hours To Replace Crankshaft Gear - Add: .1 Hour Automatic Transmission - Add: .1 Hour Locking Wheel Covers and/or Nuts - Add: .1 Hour

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.