GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN-845 Suction Device
    • EN-6361 Feeler Gauge
    • EN-6628-A Locking Tool

For equivalent regional tools, refer to Special Tools.

Removal Procedure

  1. Remove the camshaft adjuster. Refer to Camshaft Position Actuator Adjuster Removal.
  2. Remove the rear timing belt cover. Refer to Timing Belt Rear Cover Replacement.
  3. Remove intake camshaft position sensor. Refer to Camshaft Position Sensor Replacement.
  4. Remove exhaust camshaft position sensor. Refer to Camshaft Position Sensor Replacement.
  5. Remove EN-6628-A locking tool .
  6. Counterhold at hexagon of camshaft.

Adjustment Procedure

  1. Inspect the 2 valve lash, intake valve cylinder 1.
  2. 1.1. Turn the intake camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 1 are in the test position.
    1.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  3. Inspect the 2 valve lash, intake valve cylinder 3.
  4. 2.1. Turn the intake camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 3 are in the test position.
    2.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  5. Inspect the 2 valve lash, intake valve cylinder 4.
  6. 3.1. Turn the intake camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 4 are in the test position.
    3.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  7. Inspect the 2 valve lash, intake valve cylinder 2.
  8. 4.1. Turn the intake camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 2 are in the test position.
    4.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  9. When replacing the exhaust camshaft, inspect the valve lash of the exhaust valves.
  10. Inspect the 2 valve lash, exhaust valve cylinder 4.
  11. 6.1. Turn the exhaust camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 4 are in the test position.
    6.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  12. Inspect the 2 valve lash, exhaust valve cylinder 2.
  13. 7.1. Turn the exhaust camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 2 are in the test position.
    7.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  14. Inspect the 2 valve lash, exhaust valve cylinder 1.
  15. 8.1. Turn the exhaust camshaft in the direction of engine rotation by the camshaft hexagon until the cams of cylinder 1 are in the test position.
    8.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.

  16. Inspect the 2 valve lash, exhaust valve cylinder 3.
  17. 9.1. Turn the exhaust camshaft in the direction of engine rotation by the camshaft hexagon gear until the cams of cylinder 3 are in the test position.
    9.2. Insert the EN-6361 gauge , inspect the valve lash.

    Write down the result.


    Object Number: 2026542  Size: SH

    Note: Note the removal sequence 1-4.

  18. Remove the 4 camshaft bearing support bolts.
  19. Release the bearing support by striking it gently with a plastic hammer.
  20. Remove the 1st camshaft bearing support (5).
  21. Note: Mark the exhaust camshaft bearing caps before removal.

  22. Detach the camshaft bearing caps 1-4 working from outside to inside in a spiral in steps of 1/2 up to 1 turn.
  23. Remove the camshaft bearing cover from the cylinder head.
  24. Remove the intake camshaft.
  25. Note: Mark the intake camshaft bearing caps before removal.

  26. Detach the camshaft bearing caps 1-4 working from outside to inside in a spiral in steps of 1/2 up to 1 turn.
  27. Remove the camshaft bearing cover from the cylinder head.
  28. Remove the exhaust camshaft.

  29. Object Number: 1937161  Size: SH
  30. Using the EN-845 device  (1), remove the 16 valve tappets.

  31. Object Number: 1937159  Size: SH
  32. Determine valve tappet size.
  33. 20.1. Measurement of the cup tappet installed 3.12 mm (0.123 in), identification number 12.
    20.2. Measured value between cams and cup tappets +0.31 mm (0.012 in) = 3.43 mm (0.135 in).
    20.3. Required value, valve lash - 0.25 mm (0.010 in).

            Note: The identification number, arrow, is on the inside of the valve tappet.

    20.4. Measurement of the new cup tappet = 3.18 mm (0.125 in), identification number 18.
    20.5. Use a valve tappet with this dimension or one that is nearest to it.

Installation Procedure

    Note: Observe the correct assignment.

    Note: Coat the sliding surfaces with NEW engine oil.


    Object Number: 2028318  Size: SH
  1. Install the 16 valve lifter (1) use the EN 845 suction device .
  2. Install the camshafts. Refer to Camshaft Replacement.