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 .

1. 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.

   Install the timing chain oil nozzle (1).

2. Fig 1: Identifying 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.

   Loop the timing chain over the intake and exhaust camshaft actuators, aligning one of the same colored links (2) with the timing mark on the exhaust camshaft actuator (3).

NOTE:

The same colored link corresponding to the intake actuator will not initially align with the intake actuator timing mark, nor the unique colored timing chain link align with the crankshaft sprocket timing mark.

3. Ensure the crankshaft key in the 12 O'clock position. Loop the timing chain onto the crankshaft sprocket.

4. Courtesy of GENERAL MOTORS COMPANY

   NOTE:

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

   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.

7. Courtesy of GENERAL MOTORS COMPANY

   With a suitable tool, rotate the crankshaft counterclockwise to align the timing mark on the crankshaft sprocket (1) with the unique colored 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 corresponding same colored 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).

10. 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.

    Using a suitable tool, rotate the intake camshaft counterclockwise until the timing mark on the intake actuator (2) is aligned with the corresponding same colored timing link (1). Maintain tension on intake camshaft until the timing chain tensioner can be installed and activated.

11. Courtesy of GENERAL MOTORS COMPANY

    NOTE:

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

    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.
15. Fig 2: Identifying Timing Chain Links Properly Aligned To Timing Marks

    Courtesy of GENERAL MOTORS COMPANY

    Verify the timing links on the timing chain are properly aligned to the timing marks:

    1. The same colored 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.

17. Courtesy of GENERAL MOTORS COMPANY

    Install the timing chain guide (1) and bolts (2, 3) finger tight.

18. Fig 3: Identifying Front Camshaft Cap Bolts With Tightening Sequence

    Courtesy of GENERAL MOTORS COMPANY

    Tighten the front camshaft cap bolts in sequence 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.
20. Fig 4: Identifying Timing Links And 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.

    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.

    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.
21. Fig 5: Identifying 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.

    Verify the timing links on the timing chain are properly aligned to the timing marks:

    1. The same colored 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.