GM Service Manual Online
For 1990-2009 cars only

Cylinder Head Cleaning and Inspection Off Vehicle

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


    Object Number: 1289659  Size: SH

    Important: Machining of the cylinder head for flatness is not recommended as this would increase the compression ratio of the engine. If the flatness or height measurements are not within the specifications, replace the cylinder head.

  1. Clean the sealing surfaces.
  2. Inspect the cylinder head gasket and mating surfaces for leaks, corrosion, and blowby.
  3. Inspect the cylinder head for cracks.
  4. Inspect the length and the width of the cylinder head using a feeler gage and a straight edge.
  5. Check the sealing surfaces for damage. The cylinder head sealing surfaces must be flat within 0.050 mm (0.002 in) maximum.

  6. Object Number: 1289660  Size: SH
  7. Measure the height of the cylinder head from sealing surface to sealing surface. The cylinder head height should be 138.13-138.18 mm (5.438-5.440 in). If the cylinder head height is less than this value, replace the cylinder head.
  8. Inspect all threaded holes for damage.
  9. Inspect valve seats for excessive wear and burned spots.