GM Service Manual Online
For 1990-2009 cars only

Cleaning Procedure

  1. Clean the camshaft in solvent.
  2. Caution: Refer to Safety Glasses Caution in the Preface section.

  3. Dry the camshaft with compressed air.

Visual Inspection


    Object Number: 1960706  Size: SH
  1. Inspect the camshaft oil feed holes (1) to the camshaft position actuator for dirt, debris or blockage.
  2. Inspect the threaded hole (2) for damage.
  3. Inspect the camshaft position actuator locating notch (3) for damage or wear.
  4. Inspect the camshaft sealing grooves (4) for damage.
  5. Inspect the camshaft thrust surface (5) for damage.
  6. Inspect the camshaft lobes (6) and journals (7) for the following conditions:
  7. • Scoring or pitting above acceptable tolerances
    • Discoloration from overheating
    • Deformation from wear above acceptable tolerances, especially the camshaft lobes
  8. If any of the above conditions exist on the camshaft, replace the camshaft.

Camshaft Measurement


    Object Number: 1960708  Size: SH
  1. With the camshaft (1) in a suitable fixture (2), measure the camshaft (1) for wear.

  2. Object Number: 1960709  Size: SH
  3. Measure and record the camshaft journals (2) for diameter and out-of-round using an outside micrometer (1). Refer to Engine Mechanical Specifications .
  4. • If the diameter is smaller than specifications, replace the camshaft.
    • If the out-of-round exceeds specifications, replace the camshaft.

    Object Number: 1960710  Size: SH
  5. Measure and record the camshaft runout using a dial indicator (1). Refer to Engine Mechanical Specifications .

  6. Object Number: 1960711  Size: SH
  7. Measure the camshaft thrust width (A) for wear using a depth micrometer. Refer to Engine Mechanical Specifications .

  8. Object Number: 1960713  Size: SH
  9. Measure the camshaft thrust wall surface for runout using a dial indicator (1). Refer to Engine Mechanical Specifications .
  10. If the camshaft is damaged or worn beyond specifications, replace the camshaft. No machining of the camshaft is allowed.

  11. Object Number: 1960714  Size: SH
  12. Measure the camshaft lobes for wear using a dial indicator (1).

  13. Object Number: 1960715  Size: SH
  14. Place the dial indicator with the indicator tip on the base circle (2) of the camshaft lobe.
  15. 8.1. Place the dial indicator at zero.
    8.2. Rotate the camshaft until the indicator tip is at the highest point (1) on the lobe. This reading is the lift of the camshaft lobe. Refer to Engine Mechanical Specifications .
    8.3. If the indicated measurement is significantly lower than these specifications, replace the camshaft or engine performance will be reduced.