GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • J 39946 Crankshaft Socket
    • EN 46328 Camshaft Holding Tool

Removal Procedure

  1. Remove the right secondary timing chain. Refer to Secondary Camshaft Drive Chain Replacement - Right Side.

  2. Object Number: 517185  Size: SH
  3. Using the J 39946 , rotate the crankshaft until the primary timing gear alignment marks (1) are adjacent to each other as shown.
  4. Remove the left camshaft position actuator housing. DO NOT remove the actuator solenoids from the housing. Refer to Camshaft Position Actuator Housing Replacement - Left Side.
  5. Warning: Refer to Camshaft Holding Tool Warning in the Preface section.


    Object Number: 1275667  Size: SH
  6. Install the EN 46328  (1) on the bank 2 (left) camshafts (2).

  7. Object Number: 1276759  Size: SH
  8. Loosen and remove the left secondary timing chain tensioner bolts and tensioner. Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side.
  9. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution in the Preface section.


    Object Number: 1275674  Size: SH
  10. Use an open-end wrench on the hex cast into the camshaft in order to prevent the camshaft from rotating when removing the camshaft oil control valve.
  11. Loosen and remove the bank 2 (left) exhaust camshaft position oil control valve.
  12. Slide the left exhaust camshaft position actuator off of the camshaft and remove the secondary timing chain from the camshaft actuator teeth.
  13. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution in the Preface section.


    Object Number: 1275675  Size: SH
  14. Use an open-end wrench on the hex cast into the camshaft in order to prevent the camshaft from rotating when removing the camshaft oil control valve.
  15. Loosen and remove the bank 2 (left) intake camshaft position oil control valve.
  16. Slide the left intake camshaft position actuator off of the camshaft and remove the secondary timing chain from the camshaft actuator teeth.
  17. Remove the left secondary timing chain from the engine.
  18. Clean and inspect the camshaft timing drive components. Refer to Camshaft Timing Drive Components Cleaning and Inspection.

Installation Procedure


    Object Number: 1276766  Size: SH
  1. The secondary timing chain (2) has 3 black links that aid in timing the camshaft position actuators to the intermediate sprocket.
  2. The black link (4) is aligned with the bank 2 exhaust actuator timing mark. The black link (3) is aligned with the bank 2 intake actuator timing mark.
  3. The black link (1) is aligned with the intermediate sprocket.

  4. Object Number: 1272585  Size: SH
  5. The intermediate sprocket left bank timing mark is labeled left bank (LB) as shown.
  6. Assemble the secondary timing chain to the intermediate sprocket aligning the sprocket LB timing mark to the timing chain black link.

  7. Object Number: 1276768  Size: SH
  8. Align the timing mark (5) of the LB intake camshaft position actuator with the timing chain black link (3) and install the actuator on the camshaft with the actuator timing mark perpendicular (90 degrees) to the cylinder head deck surface at the top of its rotation.
  9. Loosely install the oil control valve (10) to secure the intake actuator.
  10. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution in the Preface section.

    Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 1275675  Size: SH
  11. Use an open-end wrench on the hex cast into the camshaft in order to prevent the camshaft from rotating when tightening the oil control valve to 120 N·m (89 lb ft).

  12. Object Number: 1276768  Size: SH
  13. Align the timing mark (7) of the LB exhaust camshaft position actuator with the timing chain black link (4) and install the actuator on the camshaft with the actuator timing mark perpendicular (90 degrees) to the cylinder head deck surface at the top of its rotation.
  14. Loosely install the oil control valve (8) to secure the exhaust actuator.
  15. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution in the Preface section.


    Object Number: 1275674  Size: SH
  16. Use an open-end wrench on the hex cast into the camshaft in order to prevent the camshaft from rotating when tightening the oil control valve to 120 N·m (89 lb ft).

  17. Object Number: 1276759  Size: SH
  18. Install the left secondary timing chain tensioner. Refer to Secondary Camshaft Drive Chain Tensioner Replacement - Left Side.
  19. Install the right secondary timing chain. Refer to Secondary Camshaft Drive Chain Replacement - Right Side.
  20. Remove the EN 46328 .
  21. Install the left camshaft position actuator housing. Refer to Camshaft Position Actuator Housing Replacement - Left Side.