GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 8001 Dial Indicator
    • J 8089 Carbon Removal Brush
    • J 9666 Valve Spring Tester

    Object Number: 4957  Size: SH
  1. Use the J 8089 in order to clean the carbon from the combustion chambers. Be careful not to scuff the chambers.
  2. Caution: Wear safety glasses in order to avoid eye damage.

  3. Clean the valve stems and heads of a buffing wheel.

  4. Object Number: 69538  Size: SH
  5. Clean the following components in solvent:
  6. • Valve stem keys (1)
    • Valve spring cap (3)
    • Valve spring (4)
    • Cylinder head

    Caution: Wear safety glasses in order to avoid eye damage.

  7. Dry the components with compressed air.

  8. Object Number: 64318  Size: SH
  9. Measure the cylinder head for warpage with a straight edge and feeler gauge.
  10. 5.1. A cylinder head block deck with warpage in excess of 0.10 mm (0.004 in) within a 152.4 mm (6.0 in) area must be repaired or replaced.
    5.2. A cylinder head exhaust manifold deck with warpage in excess of 0.5 mm (0.002 in) within a 152.4 mm (6.0 in) area must be repaired or replaced.
    5.3. A cylinder head intake manifold deck with warpage in excess of 0.10 mm (0.004 in) within a 152.4 mm (6.0 in) area must be repaired or replaced.

    Object Number: 4960  Size: SH
  11. Use the J 9666 in order to measure the valve spring.
  12. Replace the valve spring if the spring tension is less than 338 N (76 lb) at 43.2 mm (1.70 in).


    Object Number: 40075  Size: SH
  13. Inspect the valve springs for squareness.

  14. Object Number: 156172  Size: SH
  15. Valve stems (1) with excessive guide (2) clearance must be repaired or replaced.

  16. Object Number: 35214  Size: SH
  17. Measure the valve stem-to-guide clearance.
  18. • Excessive valve stem-to-guide clearance may cause excessive oil consumption and may also cause a valve to break. Insufficient clearance will result in noisy and sticky functioning of the valve and will disturb the engine assembly smoothness.
    • Clamp the J 8001 on the exhaust port side of the cylinder head.
    • Locate the indicator so that the movement of the valve stem from side to side (crosswise to the cylinder head) will cause a direct movement of the indicator stem.
    • The indicator stem must contact the side of the valve stem just above the valve guide.
    • Drop the valve head about 1.6 mm (0.0064 in) off the valve seat.
    • Use light pressure when moving the valve stem from side to side in order to obtain a clearance reading.