GM Service Manual Online
For 1990-2009 cars only

    Object Number: 1403955  Size: SH
  1. Remove the upper timing chain guide bolts.
  2. Remove the upper timing chain guide.

  3. Object Number: 412158  Size: SH

    Important: The timing chain tensioner must be removed to unload chain tension before the timing chain is removed.

  4. Remove the timing chain tensioner plunger.

  5. Object Number: 1403953  Size: SH
  6. Locate hex on the exhaust camshaft and hold with a wrench.
  7. Remove the exhaust camshaft bolt and the exhaust camshaft actuator.
  8. Discard the bolt.


    Object Number: 1403949  Size: SH
  9. Remove the adjustable timing chain guide bolt.
  10. Remove the adjustable timing chain guide.

  11. Object Number: 412164  Size: SH
  12. Remove the plug to gain access to the fixed timing chain guide bolt.

  13. Object Number: 412165  Size: SH
  14. Remove the fixed timing chain guide bolts.
  15. Remove the fixed timing chain guide.

  16. Object Number: 1403951  Size: SH
  17. Locate hex on the intake camshaft and hold with a wrench.
  18. Remove the intake camshaft actuator bolt, the intake camshaft actuator and the timing chain through the top of the cylinder head.
  19. Discard the bolt.


    Object Number: 467381  Size: SH
  20. Remove the crankshaft sprocket.

  21. Object Number: 412200  Size: SH
  22. Remove the timing chain oil nozzle bolt.
  23. Remove the timing chain oil nozzle.

Special Tools

EN-48953 Camshaft Actuator Locking Tool

For equivalent regional tools, refer to Special Tools.


    Object Number: 2146284  Size: SH
  1. Remove the upper timing chain guide bolts.
  2. Remove the upper timing chain guide (1).

  3. Object Number: 2148463  Size: SH

    Note: The timing chain tensioner must be removed to unload chain tension before the timing chain is removed.

  4. Remove the timing chain tensioner plunger (1).

  5. Object Number: 2128100  Size: SH
  6. Rotate intake camshaft actuators to install EN-48953 locking tool  (1).
  7. Note: Marking the chain and actuators is crucial to procedures operation. The camshaft actuator and timing chain must have oil removed from the surface prior to marking both actuators and chain.

  8. Install EN-48953 locking tool onto the cylinder head and tighten to 10 N·m (89 lb in). If the intake camshaft actuator is moving independent of cam and is not locked, rotate the intake camshaft counter-clockwise and the tool will hold the actuator, locking the actuator to the cam.
  9. Loosen the intake camshaft actuator bolt.
  10. Loosen the exhaust camshaft actuator bolt.
  11. Remove EN-48953 locking tool .

  12. Object Number: 2146286  Size: SH
  13. Locate hex on the exhaust camshaft and hold with a wrench (2).
  14. Remove the exhaust camshaft bolt and the exhaust camshaft actuator (1). Discard the bolt.

  15. Object Number: 2146287  Size: SH
  16. Remove the adjustable timing chain guide bolt.
  17. Remove the adjustable timing chain guide (1).

  18. Object Number: 2148468  Size: SH
  19. Remove the plug (1) to gain access to the fixed timing chain guide bolt.

  20. Object Number: 2146289  Size: SH
  21. Remove the fixed timing chain guide bolts.
  22. Remove the fixed timing chain guide (1).

  23. Object Number: 2146290  Size: SH
  24. Locate hex on the intake camshaft and hold with a wrench.
  25. Remove the intake camshaft actuator bolt, the intake camshaft actuator (1) and the timing chain (2) through the top of the cylinder head. Discard the bolt.

  26. Object Number: 2128101  Size: SH

    Note: The number 3 exhaust valves are open.

    Note: Note the position and direction of the camshafts before removal. Mark the cylinder head in relation to the locking notches before component removal.

  27. Mark the cylinder head where the exhaust camshaft actuator locking notch (1) and intake camshaft locking notch (2) are lined up with the cylinder head.

  28. Object Number: 2074531  Size: SH
  29. Remove the crankshaft sprocket (2) and friction washers (1), if equipped.

  30. Object Number: 2146291  Size: SH
  31. Remove the timing chain oil nozzle bolt.
  32. Remove the timing chain oil nozzle (1).