Camshaft Timing Chain and Tensioner Installation

Special Tools

• EN 45059  Angle Meter
• EN 50837  Timing Chain Tensioner Retraction Tool

For equivalent regional tools, refer to Special Tools .

Fig 1: Timing Chain Oil Nozzle
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Ensure the timing chain oil nozzle is rotated with the notch facing upward, and aligned with the tab on the engine block.

1. Install the timing chain oil nozzle (1).
Fig 2: Timing Chain Links Properly Aligned To Timing Marks
Courtesy of GENERAL MOTORS COMPANY
NOTE:

There are three colored links on the timing chain. The two links that align to the timing marks on the actuators are the same color. The timing link that aligns with the timing mark on the crankshaft sprocket is 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.

2. Loop the timing chain over the intake and exhaust camshaft actuators, aligning the unique colored link (2) with the timing mark on the exhaust camshaft actuator (3).
NOTE:

The unique colored links will not initially align with the intake actuator timing mark or the crankshaft sprocket timing mark.

3. Ensure the crankshaft key in the 12 O'clock position. Loop the timing chain onto the crankshaft sprocket.
Fig 3: Timing Chain Guide, Tensioner Pivot Arm And Bolts
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Timing will be established before the final install and torque of the guide bolts.

4. Install the timing chain guide (2) and upper bolt (1) only, finger tight.
5. Install the timing chain tensioner pivot arm (3).
6. Install the pivot arm bolt (1) finger tight.
Fig 4: Crankshaft Sprocket, Timing Link And Lower Bolt
Courtesy of GENERAL MOTORS COMPANY
7. With a suitable tool, rotate the crankshaft counterclockwise to align the timing mark on the crankshaft sprocket (1) with the timing link (2).
NOTE:
• Continue to rotate the crankshaft counterclockwise as necessary to maintain timing alignment.
• Ensure that the alignment mark on the exhaust camshaft actuator remains aligned with the timing link.
8. Rotate the lower end of the fixed timing chain guide into installation position and install the lower bolt (3).
CAUTION:

Refer to Fastener Caution .

9. Tighten the timing chain guide upper and lower bolts to 25 N.m (18 lb ft).
Fig 5: Intake Actuator & Timing link
Courtesy of GENERAL MOTORS COMPANY
NOTE:
• The timing for the exhaust camshaft actuator and the crankshaft sprocket has been established.
• Applying or loosening pressure by hand between the timing chain guides will allow the chain to slip or bind during counterclockwise rotation of the camshaft.
10. Using a suitable tool, rotate the intake camshaft counterclockwise until the timing mark on the intake actuator (2) is aligned with the timing link (1). Maintain tension on intake camshaft until the timing chain tensioner can be installed and activated.
Fig 6: Timing Chain Tensioner, Bolts And Gasket
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Ensure EN-50837  retraction tool is installed and the tensioner is locked in a compressed state before installing.

11. Install a NEW timing chain tensioner gasket (3) on the timing chain tensioner (2).
12. While maintaining the intake camshaft actuator timing alignment, install the timing chain tensioner (2) and bolts (1) and tighten to 25 N.m (18 lb ft).
13. Tighten the pivot arm bolt to 25 N.m (18 lb ft).
14. Remove EN-50837  retraction tool.
Fig 7: Timing Chain Links Properly Aligned To Timing Marks
Courtesy of GENERAL MOTORS COMPANY
15. Verify the timing links on the timing chain are properly aligned to the timing marks:
    1. The timing links (1, 2) are aligned to the appropriate timing marks on the camshaft actuators (6, 3).
    2. The unique colored link (5) is aligned to the timing mark on the crankshaft sprocket (4).
16. If they are not, repeat the portion of the procedure necessary to align the timing marks.
Fig 8: Timing Chain Guide & Bolts
Courtesy of GENERAL MOTORS COMPANY
17. Install the timing chain guide (1) and bolts (2, 3).
18. Tighten the bolts to 10 N.m (89 lb in) twice.
NOTE:

Rotating the crankshaft will engage the tensioner and remove slack from the timing chain.

19. Rotate the crankshaft slightly in a clockwise direction. If the timing chain jumps actuator teeth, repeat procedure to align the timing marks.
Fig 9: Timing Link Lines & Timing Mark
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Because of slight clockwise rotation, all chain marks may be advanced slightly in relation to the actuator and sprocket marks, yet still aligned.

NOTE:

Due to size difference of the crankshaft sprocket and the balance shaft sprocket, timing marks on the chain will not match during every crankshaft revolution. Ensure that the marks on the sprockets are aligned appropriately before installing the timing chain.

20. Verify the timing links on the balance chain are properly aligned to the timing marks:
    1. The timing link (1) is aligned to the timing mark on the crankshaft sprocket (2).
    2. The adjacent timing links (4) are aligned with both timing marks (3) on the balancer shaft driven sprocket.
Fig 10: Timing Chain Links Properly Aligned To Timing Marks
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Because of slight clockwise rotation, all chain marks may be advanced slightly in relation to the actuator and sprocket marks, yet still aligned.

21. Verify the timing links on the timing chain are properly aligned to the timing marks:
    1. The timing links (1, 2) are aligned to the appropriate timing marks on the camshaft actuators (6, 3).
    2. The unique colored link (5) is aligned to the timing mark on the crankshaft sprocket (4).
22. If they are not, repeat the portion of the procedure necessary to align the timing marks.