For 1990-2009 cars

#### Special Tools

• | EN-48953 Camshaft Actuator Locking Tool

• | J 45027 Tensioner Tool

• | J 45059 Angle Meter

For equivalent regional tools, refer to Special Tools

Note: The engine is timed top-dead center exhaust stroke.

1. Ensure the intake camshaft notch is in the 5 o'clock position (2) and the exhaust camshaft notch is in the 7 o'clock position (1). The number 1 piston should be at top dead center (TDC), crankshaft key at 12 o'clock.
2. Install a friction washer (1), if equipped.
3. Install the timing chain drive sprocket (3) to the crankshaft with the timing mark (2) in the 5 o'clock position and the front of the sprocket facing out.
4. Install a second friction washer (1), if equipped.

Note:

• | There are 3 colored links on the timing chain. 2 links are of matching color, and 1 link is of a unique color. Use the following procedure to line up the links with the actuators. Orient the chain so that the colored links are visible.

• | Always use new actuator bolts.

5. Assemble the intake camshaft actuator into the timing chain with the timing mark lined up with the uniquely colored link (1).
6. 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).
7. Install the intake camshaft actuator onto the intake camshaft while aligning the dowel pin into the camshaft slot.
8. Hand tighten the new intake camshaft actuator bolt.
9. Route the timing chain around the crankshaft sprocket and line up the first matching colored link (2) with the timing mark on the crankshaft sprocket, in approximately the 5 o'clock position.
10. Rotate the crankshaft clockwise to remove all chain slack. Do not rotate the intake camshaft.

Caution: Refer to Fastener Caution in the Preface section.

11. Install the adjustable timing chain guide down through the opening in the cylinder head and install the adjustable timing chain bolt. Tighten the adjustable timing chain guide bolt to 10 N·m (89 lb in).
12. Install the exhaust camshaft actuator (1) into the timing chain with the timing mark lined up with the second matching colored link.

Note: Always install NEW actuator bolts.

13. Install the exhaust camshaft actuator onto the exhaust camshaft, aligning the dowel pin into the camshaft slot.
14. Using a 23 mm open end wrench, rotate the exhaust camshaft approximately 45 degrees until the dowel pin in the camshaft actuator goes into the camshaft slot.
15. When the actuator seats on the cam, tighten the new exhaust camshaft actuator bolt hand tight.
16. 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.
17. Install the fixed timing chain guide and bolts and tighten to 12 N·m (106 lb in).
18. Install the upper timing chain guide and bolts. Tighten the bolts to 10 N·m (89 lb in).
19. Reset the timing chain tensioner by performing the following steps:

19.1. | Remove the snap ring.

19.2. | Remove the piston assembly from the body of the timing chain tensioner.

19.3. | Install the J 45027-2 (2) into a vise.

19.4. | Install the notch end of the piston assembly into the J 45027-2 (2).

19.5. | Using the J 45027-1 (1), turn the ratchet cylinder into the piston.

19.6. | Reinstall the piston assembly into the body of the tensioner.

19.7. | Install the snap ring.

20. Inspect the timing chain tensioner seal for damage. If damaged, replace the seal.
21. Inspect to ensure all dirt and debris is removed from the timing chain tensioner threaded hole in the cylinder head.

Note: Ensure the timing chain tensioner seal is centered throughout the torque procedure to eliminate the possibility of an oil leak.

Note: The timing chain tensioner is released by compressing it 2 mm (0.079 in), which will release the locking mechanism in the ratchet. The crankshaft balancer must be installed in order to release the tensioner. Refer to Crankshaft Balancer Installation for tensioner release instructions.

22. Install the timing chain tensioner assembly and tighten to 75 N·m (55 lb ft).
23. Install EN-48953 locking tool (1) and tighten the bolts into the cylinder head to 10 N·m (89 lb in).
24. Using a torque wrench, tighten the camshaft actuator bolt to 30 N·m (22 lb ft) , plus 100 degrees using the J 45059 angle meter .
25. Using a torque wrench, tighten the camshaft actuator bolt to 30 N·m (22 lb ft) , plus 100 degrees using the J 45059 angle meter .
26. Remove EN-48953 locking tool .
27. Install the timing chain oiling nozzle and tighten the bolt to 10 N·m (89 lb in).
28. Apply sealant compound GM P/N 12345382 (Canadian P/N 10953489) to the thread of the timing chain guide bolt access hole plug.
29. Install the timing chain guide bolt access hole plug and tighten to 90 N·m (66 lb ft).