Timing Chain: Service and Repair

Timing Chain, Sprockets, and/or Tensioner Replacement

Removal Procedure

Tool Required

J 45027 Tensioner Tool


1. Disconnect the negative battery cable.
2. Remove the camshaft cover.
3. Remove the No. 1 cylinder spark plug.
4. Rotate the crankshaft in the engine rotational direction clockwise, until the No. 1 piston is at top dead center (TDC) on the compression stroke.
5. Raise and support the vehicle.
6. Remove the engine front cover.
7. Lower the vehicle.
8. Remove the camshaft cover.







Important: The timing chain tensioner must be removed to unload chain tension before the timing chain is removed. If not removed, the timing chain will become cocked and it will be difficult to remove.


9. Remove the timing chain tensioner.







10. Remove the upper timing chain guide.







11. Use a 24 mm wrench to hold the camshaft from turning.






12. Remove the exhaust camshaft sprocket bolt and discard.
13. Remove the exhaust camshaft sprocket.








14. Remove the timing chain tensioner guide.







15. Remove the engine mount
16. Remove the fixed timing chain guide access plug.







17. Remove the fixed timing chain guide.







18. Remove the intake camshaft sprocket bolt and discard.
19. Remove the intake camshaft sprocket.
20. Remove the timing chain through the top of the cylinder head.






21. Remove the crankshaft sprocket.







22. Remove the oil nozzle and bolt.
23. Remove the balance shaft chain tensioner.








24. Remove the adjustable balance shaft drive chain guide.







25. Remove the small balance shaft drive chain guide.







26. Remove the upper balance shaft drive chain guide.







27. Remove the balance shaft drive chain.


Installation Procedure







Notice: Refer to Fastener specs.

Important: If the balance shafts are not properly timed to the engine, the engine may vibrate and make noise.

1. Install the upper balance shaft chain guide.
Tighten the upper balance shaft chain guide bolts to 15 Nm (133 inch lbs.).






2. Install the small balance shaft chain guide.
3. Tighten the balance shaft chain guide bolts.
Tighten the chain guide bolts to 10 Nm (89 inch lbs.).






4. Install the adjustable balance shaft drive chain guide.
Tighten the chain guide bolts to 10 Nm (89 inch lbs.).






5. Turn the tensioner plunger 90 degrees in its bore and compress the plunger until a paper clip can be inserted through the hole in the plunger body and into hole in the tensioner plunger.
6. Install the timing chain tensioner.
7. Tighten the chain tensioner bolts.
Tighten the chain tensioner bolts to 10 Nm (89 inch lbs.).
8. Remove the paper clip from the balance shaft drive chain tensioner.
9. Install the oil nozzle and bolt.

Tighten
Tighten the oil nozzle blot to 10 Nm (89 lb in).







10. Install the crankshaft sprocket with timing mark at the 5 o'clock position.







11. Lower the timing chain through the opening in the top of the cylinder head. Carefully ensure that the chain goes around both sides of the cylinder block bosses (1, 2).







12. Install the intake camshaft sprocket with the INT diamond at the 2 o'clock position.
13. Hand tighten a NEW intake camshaft sprocket bolt.
14. Route the timing chain around the crankshaft sprocket with the matching color link aligning with the timing mark.
15. Route the timing chain around the intake camshaft sprocket with the uniquely colored link (1) aligning with the INT diamond.








16. Install the timing chain tensioner guide through the opening in the top of the cylinder head.

Tighten the timing chain tensioner guide bolt to 10 Nm (89 inch lbs.).







17. Install the exhaust camshaft sprocket with the timing chain silver link (3) at EXH triangle aligned at the 10 o'clock position.







18. Use a 24 mm wrench to rotate the camshaft slightly, until exhaust sprocket aligns with the camshaft.
19. Hand tighten the NEW exhaust camshaft sprocket bolt.







20. Install the fixed timing chain guide.

Tighten
Tighten the fixed timing chain bolts to 15 Nm (133 inch lbs.).








21. Verify that all the colored links are aligned with the appropriate exhaust (1), intake (2), and crankshaft marks (3).









22. apply sealant, GM P/N 12345382 (Canadian P/N 10953489) to thread and install the timing chain guide bolt access hole plug

Tighten
Tighten the access hole plug to 90 Nm (66 lb ft).



23. Install the engine mount.







24. inspect the timing chain tensioner. If the timing chain tensioner, O-ring, or washer is damaged, replace the timing chain tensioner.
25. Measure the timing chain tensioner assembly from end to end.


A new tensioner should be supplied in the fully compressed non-active state. A tensioner in the compressed state will measure 72 mm (2.83. in) (a) from end to end. A tensioner in the active state will measure 85 mm (3.35 in) (a) from end to end.








26. If the timing chain tensioner is not in the compressed state, perform the following steps:

26.1. Remove the piston assembly from the body of the timing chain tensioner by pulling in out.
26.2. Install the J 45027-2 (2) into a vise.
26.3. Install the notch end of the piston assembly into the J 45027-2 (2).
26.4. Using the J 45027-1 (1), turn the ratchet cylinder into the piston.

27. Inspect the bore of the tensioner body for dirt, debris, and damage. If any damage appears, replace the tensioner. Clean dirt or debris out with a lint free cloth.
28. Install the compressed piston assembly back into the timing chain tensioner body until it stops at the bottom of the bore. Do not compress the piston assembly against the bottom of the bore. If the piston assembly is compressed against the bottom of the bore, it will activate the tensioner, which will then need to be reset again.
29. At this point the tensioner should measure approximately 72 mm (2.83 in) (a) from end to end. If the tensioner does not read 72 mm (2.83 in) (a) from the end to end repeat steps 25.1 and 25.4.







30. Inspect to ensure all dirt and debris is removed from the timing chain tensioner threaded hole in the cylinder head.
31. Install the new timing chain tensioner assembly.

Tighten
Tighten the timing chain tensioner to 75 Nm (55 ft. lbs.).

32. The timing chain tensioner is released by compressing it 2 mm (0.079 inch) which will release the locking mechanism in the ratchet. To release the timing chain tensioner, use a suitable tool with a rubber tip on the end. Feed the tool down through the cam drive chest to rest on the cam chain. Then give a sharp jolt diagonally downwards to release the tensioner.






33. Use a 24 mm wrench to hold the camshaft.

Tighten
Tighten the NEW camshaft bolts to 85 Nm (63 ft. lbs.) plus 30 degrees.






34. Install the upper timing chain guide.

Tighten
Tighten the upper guide bolts to 10 Nm (89 lb in).

35. Install the camshaft cover
36. Raise the vehicle.
37. Install the engine front cover.
38. Lower the vehicle.
39. Connect negative battery cable.