Camshaft Timing Chain, Sprocket, and Tensioner Installation (LAF, LEA, or LUK)

Special Tools

• EN-45027  Tensioner Tool
• EN 45059  Angle Meter
• EN-48953  Camshaft Actuator Locking Tool

For equivalent regional tools, refer to Special Tools .

Fig 1: Camshaft Notches
Courtesy of GENERAL MOTORS COMPANY
NOTE:

The engine is timed top-dead center exhaust stroke.

1. Ensure the intake camshaft notch is in the 10 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.
Fig 2: View of Friction Washer and Timing Chain Drive Sprocket
Courtesy of GENERAL MOTORS COMPANY
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.
NOTE:

The outer spacer/washer (1) is in between the crank/balancer pulley and the lower timing gear and may remain in place when the pulley is removed. The spacer/washer (1) has a dot/mark on its surface that may be mistaken for the lower timing mark, and blocks the proper timing mark on the gear from view. The outer spacer/washer (1) must be removed when timing the engine in order to view the correct timing mark on the lower crank gear.

4. Install a second friction washer (1), if equipped.
Fig 3: Identifying Colored Links On Timing Chain
Courtesy of GENERAL MOTORS COMPANY
NOTE:

There are three colored links on the timing chain. Two links are of matching color, and one 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.

5. Assemble the intake camshaft actuator into the timing chain with the timing mark lined up with the uniquely colored link (1).
Fig 4: Identifying Cylinder Head Opening
Courtesy of GENERAL MOTORS COMPANY
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.
NOTE:

Always use NEW actuator bolts.

8. Hand tighten the new intake camshaft actuator bolt.
Fig 5: Identifying Timing Mark on Crankshaft Sprocket and Lining Up With First Matching Colored Link
Courtesy of GENERAL MOTORS COMPANY
9. Route the timing chain around the crankshaft sprocket and line up the first matching colored link (1) with the timing mark on the crankshaft sprocket, in approximately the 5 o'clock position.
Fig 6: View of Adjustable Timing Chain Guide Bolt.
Courtesy of GENERAL MOTORS COMPANY
10. Rotate the crankshaft clockwise to remove all chain slack. Do not rotate the intake camshaft.
CAUTION:

Refer to Fastener Caution .

11. Install the adjustable timing chain guide (1) down through the opening in the cylinder head and install the adjustable timing chain bolt and tighten to 10 N.m (89 lb in).
Fig 7: View of Exhaust Camshaft Actuator
Courtesy of GENERAL MOTORS COMPANY
12. Install the exhaust camshaft actuator (1) into the timing chain with the timing mark lined up with the second matching colored link.
Fig 8: Exploded View of Exhaust Camshaft Actuator
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Always install NEW actuator bolts.

13. Install the exhaust camshaft actuator (1) onto the exhaust camshaft, aligning the dowel pin into the camshaft slot.
14. Using a 23-24 mm open end wrench, rotate the exhaust camshaft clockwise until the dowel pin in the camshaft actuator goes into the camshaft slot.
Fig 9: View of Actuator
Courtesy of GENERAL MOTORS COMPANY
15. When the actuator (1) 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.
Fig 10: View of Fixed Timing Chain Guide
Courtesy of GENERAL MOTORS COMPANY
17. Install the fixed timing chain guide (1) and bolts and tighten to 12 N.m (106 lb in).
Fig 11: View of Timing Chain and Tensioner
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Apply one drop of Loctite™, or equivalent, prior to installing the guide bolts.

18. Install the upper timing chain guide (1) and bolts and tighten to 10 N.m (89 lb in).
Fig 12: Compressing Timing Chain Tensioner
Courtesy of GENERAL MOTORS COMPANY
19. Reset the timing chain tensioner by performing the following steps:
    1. Remove the snap ring.
    2. Remove the piston assembly from the body of the timing chain tensioner.
    3. Install the EN-45027-2 (2)  tensioner into a vise.
    4. Install the notch end of the piston assembly into the EN-45027-2 (2)  tensioner.
    5. Using the EN-45027-1 (1)  tensioner, turn the ratchet cylinder into the piston.
    6. Reinstall the piston assembly into the body of the tensioner.
    7. Install the snap ring.
Fig 13: View of Timing Chain Tensioner Seal
Courtesy of GENERAL MOTORS COMPANY
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.

22. Install the timing chain tensioner assembly (1) and tighten to 75 N.m (55 lb ft).
NOTE:

The timing chain tensioner is released by compressing it 2 mm (0.079 in), which will release the locking mechanism in the ratchet.

23. The crankshaft balancer must be installed in order to release the tensioner. Refer to Crankshaft Balancer Installation .
Fig 14: View Locking Tool
Courtesy of GENERAL MOTORS COMPANY
24. Install EN-48953  locking tool (1) and tighten the bolts into the cylinder head to 10 N.m (89 lb in).
25. Using a torque wrench, tighten the intake camshaft actuator bolt to 30 N.m (22 lb ft), plus 100 degrees using the EN 45059  meter.
26. Using a torque wrench, tighten the exhaust camshaft actuator bolt to 30 N.m (22 lb ft), plus 100 degrees using the EN 45059  meter.
27. Remove EN-48953  locking tool.
Fig 15: View of Timing Chain Oil Nozzle
Courtesy of GENERAL MOTORS COMPANY
28. Install the timing chain oiling nozzle (1) and tighten the bolt to 10 N.m (89 lb in).
Fig 16: Timing Chain Guide Bolt Access Hole Plug
Courtesy of GENERAL MOTORS COMPANY
29. Apply sealant to the thread of the timing chain guide bolt access hole plug. Refer to Adhesives, Fluids, Lubricants, and Sealers .
30. Install the timing chain guide bolt access hole plug (1) and tighten to 75 N.m (55 lb ft).