GM Service Manual Online
For 1990-2009 cars only
  1. Remove the spark plugs from the cylinder heads. Refer to Spark Plug Replacement .

  2. Object Number: 1950892  Size: SH

    Important: 

       • With the components at room temperature.
       • Mark, organize, or sort the cylinder head components for assembly. Return the components to their original location during assembly.

  3. Use a commercially available valve spring compressor in order to compress the valve spring.

  4. Object Number: 1950893  Size: SH
  5. Remove the valve stem keys (2).
  6. Release the spring compressor and remove from the cylinder head (1).
  7. Remove the valve spring cap (3).
  8. Remove the valve spring (4).
  9. Remove the valve (7).
  10. Remove the valve stem oil seal (5). Refer to Separating Parts .
  11. Repeat steps 2-8 for each valve as required.
  12. Important: DO NOT remove the coolant core plugs (6) unless servicing is required. These will be damaged on removal and must be replaced.

  13. Remove the cylinder head core hole plugs (6), as required.

  14. Object Number: 1950891  Size: SH

    Notice: Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

  15. Remove the ECT sensor (1) from the cylinder head.

  16. Object Number: 1950895  Size: SH
  17. Remove the coolant plug (2) from the right cylinder head (1).

  18. Object Number: 1950896  Size: SH
  19. Check all valve springs for distortion. There should be no more than 1.6 mm variance (1) of the spring end while the spring is being rotated on a flat surface.
  20. Replace springs that exceed this specification.


    Object Number: 1950897  Size: SH
  21. Use a commercially available valve spring tester and measure each valve spring for free height and tension. Refer to Engine Mechanical Specifications .