Timing Chain: Service and Repair
Timing Chain, Sprockets, and/or Tensioner Replacement
Tools Required
* J 45027 Tensioner Tool
* J 45059 Angle Meter
Removal Procedure
1. Remove the hood.
2. Remove the #1 cylinder spark plug.
3. Rotate the crankshaft in the engine rotational direction clockwise, until the #1 piston is at top dead center (TDC) on the compression stroke.
4. Remove the camshaft cover.
5. Remove the engine front cover.
6. Remove the upper timing chain guide bolts and guide.
Important: The timing chain tensioner must be removed to unload chain tension before the timing chain is removed. If it is not, the timing chain will become cocked and it will be difficult to remove.
7. Remove the timing chain tensioner.
8. Install a 24 mm wrench on the hex on the exhaust camshaft in order to hold the camshaft.
9. Remove and discard the exhaust camshaft actuator bolt (2).
10. Remove the exhaust camshaft actuator (1, 3) from the camshaft and timing chain.
11. Remove the timing chain tensioner guide bolt and guide.
12. Remove the fixed timing chain guide access plug.
13. Remove the fixed timing chain guide bolts and guide.
14. Install a 24 mm wrench on the hex on the intake camshaft in order to hold the camshaft.
15. Remove and discard the intake camshaft actuator bolt (2).
16. Remove the intake camshaft actuator (3), and the timing chain through the top of the cylinder head.
17. Remove the timing chain crankshaft sprocket.
18. If replacing the balance shaft timing chain and sprocket, perform the following steps: if not proceed the step 10 in the installation procedure.
19. Remove the balance shaft drive chain tensioner bolts and tensioner.
20. Remove the adjustable balance shaft chain guide bolt and guide.
21. Remove the small balance shaft drive chain guide bolts and guide.
22. Remove the upper balance shaft drive chain guide bolts and guide.
Important: It may ease removal of the balance shaft drive chain to get all the slack in the chain between the crankshaft and water pump sprockets.
23. Remove the balance shaft drive chain (7).
24. Remove the balance shaft drive sprocket.
Installation Procedure
1. If replacing the balance shaft timing chain, perform the following steps, if not proceed to step 10.
2. Install the balance shaft drive sprocket.
Important: If the balance shafts are not properly timed to the engine, the engine may vibrate or make noise.
3. Install the balance shaft drive chain (1) with the colored link lined up with the marks on the balance shaft sprockets and the balance shaft drive sprocket. There are three colored links on the chain. Two are chrome and one is copper. Use the following steps in order to line up the links with the sprockets.
* Place the copper link (5) so that it lines up with the timing mark (2) on the intake side balance shaft sprocket.
* Working clockwise around the chain, place the chrome link (4) in line with the timing mark (3) on the balance shaft drive sprocket. (approximately 6 o'clock position on the sprocket).
* Place the chain (7) on the water pump drive sprocket. The alignment is not critical.
* Align the last chrome link (6) with the timing mark (1) on the exhaust side balance shaft drive sprocket.
Notice: Refer to Fastener Notice.
4. Install the upper balance shaft drive chain guide and bolts.
Tighten the bolts to 15 N.m (11 lb ft).
5. Install the small balance shaft drive chain guide and bolts.
Tighten the bolts to 15 N.m (11 lb ft).
6. Install the adjustable balance shaft chain guide and bolt.
Tighten the bolt to 10 N.m (89 lb in).
7. Reset the timing chain tensioner by performing the following steps:
* Rotate the tensioner plunger 90 degrees in its bore and compress the plunger.
* Rotate the tensioner back to the original 12 o'clock position and insert a paper clip through the hole in the plunger body and into the hose in the tensioner plunger.
8. Install the balance shaft drive chain tensioner and bolts.
Tighten the bolts to 10 N.m (89 lb in).
9. Remove the paper clip from the balance shaft drive chain tensioner.
10. Ensure the intake camshaft notch is in the 5 o'clock position (2) and the exhaust camshaft is in the 7 o'clock position (1). The number 1 piston should be at top dead center (TDC), the crankshaft key should be at the 12 o'clock position.
11. Install the timing chain crankshaft sprocket to the crankshaft with the timing mark in the 5 o'clock position.
Important:
* There are 3 colored links on the timing chain. Two links are pink in color and one link is blue in color. Use the following procedure to line up the links with the sprockets. Orient the chain so that the colored links are visible.
* Always use NEW actuator bolts.
Assemble the intake camshaft actuator to the timing chain with the timing mark lined up with the blue colored link (1). Install and hand tighten a NEW intake camshaft actuator bolt.
12. Lower the timing chain through the opening in the cylinder head. Use care to ensure that the chain goes around both sides of the cylinder block bosses (1, 2).
13. Route the timing chain around the crankshaft sprocket and line up the first pink link with the timing mark on the crankshaft sprocket, in approximately the 5 o'clock position.
14. Install the adjustable timing chain guide through the opening in the cylinder head. Install the adjustable timing chain bolt.
Tighten the bolt to 10 N.m (89 lb in).
Important: Always install NEW sprocket bolts.
15. Install the exhaust camshaft actuator (1) and a NEW bolt (2) loosely onto the exhaust camshaft.
16. Align the timing mark on the actuator with the last pink colored link. Tighten the bolt finger tight.
Notice: Do not rotate either camshaft more than half turn in either direction with crankshaft at top dead center (TDC). To do so may cause valve to piston contact resulting in a damaged valve and/or a damaged piston.
17. If the camshaft is 180 degrees out of time, use the following procedure to re-align the camshaft. Using a 24-mm wrench, first turn the intake camshaft until the alignment feature on the back of the camshaft actuator seats in the notch in the front of the intake camshaft.
1. Turn the crankshaft 45 degrees in either direction.
2. Turn the intake cam to the appropriate location.
3. Turn the crankshaft back to TDC.
18. When the actuator seats on the cam, tighten the actuator bolt hand tight.
19. Verify that all of the colored links and the appropriate timing marks are still aligned. If they are not, repeat the portion of the procedure necessary to align the timing marks.
20. Install the fixed timing chain guide and bolts.
Tighten the bolts to 10 N.m (89 lb in).
21. Install the upper timing chain guide and bolts.
Tighten the bolts to 10 N.m (89 lb in).
22. Install a 24 mm wrench onto the hex on the intake camshaft. Using a torque wrench, tighten the camshaft actuator bolt.
Tighten the bolt to 85 N.m (63 lb ft), plus 30 degrees using the J 45059.
23. Install a 24 mm wrench onto the hex on the exhaust camshaft. Using a torque wrench, tighten the camshaft actuator bolt.
Tighten the bolt to 85 N.m (63 lb ft), plus 30 degrees J 45059.
24. Remove the old oil from the timing chain tensioner.
25. Inspect the timing chain tensioner. If the timing tensioner, O-ring seal, or washer is damaged, replace the timing chain tensioner.
26. 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.
27. If the timing chain tensioner is not in the compressed state, perform the following steps:
1. Remove the piston assembly from the body of the timing chain tensioner by pulling it out.
2. Install the J 45027-2 (2) into a vise.
3. Install the notch end of the piston assembly into the J 45027-2 (2).
4. Using the J 45027-1 (1), turn the ratchet cylinder into the piston.
28. Inspect the bore of the tensioner body for dirt, debris, and damage. If any damage appears, replace the tensioner. Clean dirt or debris with a lint free cloth.
29. Install the compressed piston assembly back into the timing chain tensioner body until the assembly 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, the assembly will activate the tensioner, which will then need to be reset again.
30. 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 end to end repeat steps 27.1 thorough 27.4.
31. Ensure that all dirt and debris are removed from the timing chain tensioner threaded hole in the cylinder head.
32. Install the timing chain tensioner.
Tighten the tensioner to 75 N.m (66 lb ft).
33. The timing chain tensioner is released by compressing the tensioner 2 mm (0.079 in) 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.
34. Apply sealant GM P/N 12345382 (Canadian P/N 10953489) or equivalent, to the threads and install the timing chain guide bolt access hole plug.
Tighten the plug to 90 N.m (59 lb ft).
35. Install the engine front cover.
36. Install the camshaft cover.
37. Install the #1 cylinder spark plug.
38. Install the hood.