GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN-48749 Timing Chain Retention Tool Kit
    • EN-48953 Camshaft Actuator Locking Tool
    •  J 45059 Angle Meter

Removal Procedure


    Object Number: 1578296  Size: SH
  1. Remove the camshaft cover. Refer to Camshaft Cover Replacement.
  2. Remove the upper timing chain guide bolts and guide.

  3. Object Number: 2066456  Size: SH
  4. Install a 24 mm wrench onto the hex on the camshaft in order to rotate the camshafts clockwise and install the camshaft actuator retainer EN-48953 (1).
  5. Notice: Refer to Fastener Notice in the Preface section.

  6. Install the camshaft actuator retainer bolts.
  7. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  8. Loosen, but DO NOT remove the intake camshaft actuator bolt.
  9. Remove the camshaft actuator locking tool, EN-48953 (1).
  10. Important: Ensure the timing chain and the camshaft position actuators are marked for proper assembly.

  11. Mark the intake and exhaust camshaft actuators and the respective locations on the timing chain.

  12. Object Number: 412158  Size: SH
  13. Remove the timing chain tensioner.

  14. Object Number: 2066475  Size: SH

    Important: The camshaft actuators should not rotate during the removal or installation.

    Important: Ensure the tips of the are fully engaged into the timing chain. The retention tool rod can be used on the back side of the chain to ensure the teeth from the retention tool are engaged.

  15. Install the timing chain retention tool EN-48749 (1) to the intake side of the timing chain.

  16. Object Number: 1578297  Size: SH
  17. Remove and discard the intake camshaft actuator bolt (2).
  18. Rotate the exhaust camshaft clockwise slightly to take the tension off of the timing chain on the intake actuator.
  19. Remove the intake camshaft actuator (3) from the camshaft while also removing the actuator from the timing chain.

Installation Procedure


    Object Number: 1578297  Size: SH

    Important: Ensure that the alignment mark made previously on the exhaust camshaft actuator is still aligned properly with the mark on the timing chain.

  1. Install the timing chain onto the intake camshaft actuator.
  2. Align the intake camshaft actuator alignment mark made previously with the timing chain mark and install the actuator until fully seated onto the camshaft.
  3. Install a NEW intake camshaft actuator bolt (2) until snug.

  4. Object Number: 2066475  Size: SH
  5. Remove the timing chain retention tool (1) from the intake side of the timing chain.
  6. Reset and install the timing chain tensioner. Refer to Timing Chain Tensioner Replacement.

  7. Object Number: 2066456  Size: SH
  8. Install the camshaft actuator retainer (1).
  9. Install the camshaft actuator retainer bolts.
  10. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  11. Tighten the NEW camshaft actuator bolt.
  12. Tighten
    Tighten the bolt to 85 N·m (63 lb ft), plus an additional 30 degrees using the J 45059 .


    Object Number: 1578296  Size: SH

    Important: You have to have EN-48953 installed to do this part of procedure.

  13. Release the tensioner by rotating the crankshaft balancer bolt counterclockwise.
  14. Torque
    Torque to 45 N·m (33 lb ft).

  15. Remove the camshaft actuator retainer EN-48953  (1).
  16. Install the upper timing chain guide and bolts.
  17. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  18. Install the camshaft cover. Refer to Camshaft Cover Replacement.