GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN-48313 Timing Chain Retention Tool
    • EN 46111 Crankshaft Rotation Socket

Removal Procedure

  1. Remove the lower intake manifold. Refer to Lower Intake Manifold Replacement .
  2. Remove the camshaft cover. Refer to Camshaft Cover Replacement - Right Side .
  3. Remove the camshaft sensors. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust and Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake .
  4. Remove the intake camshaft position actuator solenoid. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Intake .
  5. Remove the crankshaft balancer. Refer to Crankshaft Balancer Replacement .

  6. Object Number: 1306310  Size: SH
  7. Rotate the crankshaft with the EN 46111 until the camshafts are in a neutral (low tension) position. The camshaft flats will be parallel with the camshaft cover rail (1).
  8. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.


    Object Number: 1340931  Size: SH

    Important: 

       • Use an open-end wrench at the camshaft hex to prevent camshaft/engine rotation.
       • DO NOT remove the camshaft position actuator bolt at this time.

  9. Loosen the camshaft position actuator bolt.

  10. Object Number: 1858791  Size: SH
  11. Unscrew the EN-48313 so the legs of the tool are retracted.
  12. Insert the EN-48313 between the camshaft actuators, rearward of the timing chain until the top line that is scribed in the body of the tool (1) is adjacent to the top surface of the cylinder head (2). This is the approximate installed position.

  13. Object Number: 1858794  Size: SH

    Important: The engine front cover is removed for clarity in the following graphics, but NOT required to perform the procedure.

  14. Ensure that the feet (2) on the legs of the tool are facing the front of the engine.
  15. Partially expand the legs (1) of the EN-48313 by turning the T-shaped handle clockwise.
  16. Continue expanding the EN-48313 until the feet (2) contact the timing chain. Do not tighten at this time.

  17. Object Number: 1858603  Size: SH

    Important: 

       • Ensure that the foot (1) of the EN-48313 is engaged into one of the link pockets to prevent chain slippage during tightening of the EN-48313 .
       • Do not allow the body of the EN-48313 to rotate when tightening the T-handle.

  18. Hand tighten the EN-48313 .
  19. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  20. Use an open end wrench on the hex cast into the body of the EN-48313 and hand tighten the T-handle.
  21. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  22. Use an open end wrench on the hex cast into the right intake and exhaust camshafts and rotate the camshafts towards each other in order to create slack in the chain between the actuators.

  23. Object Number: 1858795  Size: SH
  24. The EN-48313 is now properly installed to hold the timing chain in position.

  25. Object Number: 1306457  Size: SH

    Important: Ensure that the camshaft timing chain and the camshaft position actuators are marked for proper assembly.

  26. Mark the timing chain and the respective locations on camshaft position actuators (15-18).
  27. Remove the camshaft position actuator bolt.
  28. Remove the camshaft bearing caps and the camshaft. Refer to Camshaft Removal - Right Side .

Installation Procedure


    Object Number: 1306457  Size: SH

    Important: 

       • Ensure that the marks on the camshaft position actuators and the timing chain (15-18) are aligned.
       • DO NOT tighten the camshaft position actuator bolt at this time.

  1. Locate the camshafts to the cylinder head and assemble the camshaft actuators to the camshafts.
  2. Install the camshafts and the camshaft bearing caps. Refer to Camshaft Installation - Right Side .
  3. Remove the EN-48313 .
  4. Install the crankshaft balancer. Refer to Crankshaft Balancer Replacement .
  5. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.


    Object Number: 1340931  Size: SH

    Important: Use an open-end wrench at the camshaft hex to prevent camshaft/engine rotation.

  6. Install and tighten the camshaft position actuators. Refer to Camshaft Position Actuator Installation - Right Side Intake and Camshaft Position Actuator Installation - Right Side Exhaust .
  7. Install the intake camshaft position actuator solenoid. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Intake .
  8. Install the camshaft sensors. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust and Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake .
  9. Install the camshaft cover. Refer to Camshaft Cover Replacement - Right Side .
  10. Install the lower intake manifold. Refer to Lower Intake Manifold Replacement .