GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • J 39946 Crankshaft Socket
    • EN 46328 Camshaft Holding Tool

Removal Procedure


    Object Number: 1272598  Size: SH
  1. Remove the left secondary camshaft tensioner (2). Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side.
  2. Remove the left camshaft position actuator housing. DO NOT remove the camshaft sensors from the housing. Refer to Camshaft Position Actuator Housing Replacement - Left Side.

  3. Object Number: 1275681  Size: SH
  4. Using the J 39946 (1) , rotate the crankshaft until both camshaft position actuator timing marks are at the top of their rotation.
  5. Warning: Refer to Camshaft Holding Tool Warning in the Preface section.


    Object Number: 1275659  Size: SH
  6. Install the EN 46328 (2).

  7. Object Number: 1275692  Size: SH

    Note: The secondary timing chain has black links that are used for alignment when the primary and secondary timing gear and chain assemblies are being installed together. IT IS NOT NECESSARY for the black chain links to be aligned with the camshaft actuator timing marks when the secondary chain and gear components are being serviced separately.

  8. Use a paint stick to create a mark on the timing chain link (1) adjacent to each camshaft position actuator timing mark (3).
  9. Use a paint stick to create a mark on a primary chain link and intermediate primary chain sprocket tooth adjacent to the primary chain link.

  10. Object Number: 1275677  Size: SH
  11. Use an open end wrench on the hex cast into the right intake camshaft to prevent the camshaft from rotating when loosening the camshaft oil control valve.

  12. Object Number: 1261666  Size: SH
  13. Loosen and remove the left exhaust oil control valve.
  14. Slide the left exhaust camshaft actuator off of the camshaft, disengage the sprocket teeth from the secondary timing chain, and remove the actuator.

  15. Object Number: 685354  Size: SH
  16. Remove the upper left secondary camshaft drive chain guide bolt.

  17. Object Number: 685368  Size: SH
  18. Remove the lower right secondary camshaft drive chain guide bolt.

  19. Object Number: 685372  Size: SH
  20. Remove the left secondary camshaft drive chain guide.
  21. Clean and inspect the camshaft timing drive components. Refer to Camshaft Timing Drive Components Cleaning and Inspection.

Installation Procedure


    Object Number: 685372  Size: SH
  1. Position the left secondary camshaft drive chain guide in through the left front cylinder head as shown.
  2. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 685368  Size: SH
  3. Install the left secondary camshaft drive chain guide bolts and tighten to 25 N·m (18 lb ft).

  4. Object Number: 685354  Size: SH
  5. Install the left secondary camshaft drive chain tensioner. Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side.
  6. Install the left exhaust camshaft actuator. Refer to Camshaft Position Actuator Replacement - Bank 2 (Left Side) Exhaust.

  7. Object Number: 1275693  Size: SH
  8. Ensure that the previously created paint marks (1, 3) still line up with the sprocket timing marks (2, 4).