GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 8089 Carbon Removing Brush
    • J 9666 Valve Spring Tester

    Object Number: 26157  Size: SH
  1. Inspect the cylinder head gasket and the mating surfaces. Inspect for leaks, corrosion, and blowby.
  2. If the gasket failed, determine the cause. The following conditions may cause gasket failure:
  3. • Improper installation
    • A loose or warped cylinder head
    • Missing, off location, or not fully seated dowel pins
    • Low torque on the cylinder head bolts
    • Cylinder head bolts with the incorrect length
    • A warped engine block surface
    • Scratched surfaces
    • Excessive intake manifold torque
    • Cracked engine block threaded holes

    Caution: Refer to Safety Glasses Caution in the Preface section.


    Object Number: 4957  Size: SH

    Important: Do not scuff the chamber.

  4. Use the J 8089 in order to remove the carbon from the combustion chambers.
  5. Clean the following components:
  6. •  The gasket surfaces
    • Do not use a motorized brush on any gasket sealing surface.
    • Valve stems and heads on a buffing wheel
    • The bolt hole threads
    • Remove all dirt, debris, or threadlocking material from the bolt holes.

    Object Number: 36712  Size: SH
  7. Inspect the cylinder head mating surfaces for flatness. Recondition the cylinder head mating surface, if necessary, by milling. Replace the cylinder head if you must remove more than 0.25 mm (0.010 in).
  8. Inspect the cylinder head for cracks.
  9. Inspect the cylinder head deck for corrosion. Do not attempt to weld the cylinder head. If the cylinder head is damaged, replace the cylinder head.

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

  12. Object Number: 4960  Size: SH
  13. Use the J 9666 in order to measure the valve spring tension.
  14. Replace the spring if the spring tension is not within specification.