GM Service Manual Online
For 1990-2009 cars only

Valve Clearance Inspection

  1. Remove the engine under right cover.
  2. Remove the engine cover. Refer to Engine Cover Replacement.
  3. Remove the ignition coil assembly. Refer to Ignition Coil Replacement.
  4. Remove the spark plug. Refer to Spark Plug Replacement.
  5. Remove the cylinder head cover. Refer to Camshaft Cover Replacement.

  6. Object Number: 2017553  Size: SH
  7. Set No. 1 cylinder to TDC/compression.
  8. Check only the valves indicated.
  9. • Using a feeler gage, measure the clearance between the valve lifter and camshaft.
    • Record any out-of-specification valve clearance measurements. They will be used later to determine the required replacement valve clearance lifters.
  10. Turn the crankshaft 1 revolution (360°) and set the No. 4 cylinder to TDC/compression.

  11. Object Number: 2017554  Size: SH
  12. Check only the valves indicated.
  13. • Using a feeler gage, measure the clearance between the valve lifter and camshaft.
    • Record any out-of-specification valve clearance measurements. They will be used later to determine the required replacement valve lifters.

Valve Clearance Adjustment

  1. Remove the exhaust camshaft. Refer to Exhaust Camshaft and Valve Lifter Replacement.
  2. Remove the intake camshaft. Refer to Intake Camshaft and Valve Lifter Replacement.

  3. Object Number: 2017555  Size: SH
  4. Using a micrometer, measure the thickness of the removed valve lifters.
  5. Calculate the thickness of a new lifter so that the valve clearance comes within the specified values.
  6. Calculation Example (intake):
  7. 5.1. Measured intake valve clearance equals 0.40 mm (0.0158 in).

    (Measured-Specification = Excess clearance) (a) 0.40 mm (0.0158 in.) - 0.24 mm (0.0094 in.) = 0.16 mm (0.0063 in.)

    5.2. Measured used lifter thickness equals 5.250 mm (0.2067 in).
    5.3. New lifter thickness equals 5.410 mm (0.2130 in.) (Excess clearance + Used lifter thickness = Ideal new lifter).

    (a) 0.16 mm (0.0063 in.) + 5.250 mm (0.2067 in.) = 5.410 mm (0.2130 in.)


    Object Number: 2017557  Size: SH
    5.4. Closest new lifter equals 5.420 mm (0.2134 in.) - Select No. 42 lifter.

    Note: 

       • Lifters are available in 35 sizes in increments of 0.020 mm (0.0008 in), from 5.060-5.740 mm (0.1992-0.2260 in).
       • The identification number inside the valve lifters shows the value to 2 decimal places. The illustration shows 5.420 mm (0.2134 in).

  8. Select a new lifter with a thickness as close as possible to the calculated values. Refer to Engine Mechanical Specifications for the Selective Lifter Thickness Table.
  9. Standard intake valve clearance (cold): 0.19-0.29 mm (0.007-0.011 in).
  10. EXAMPLE: The 5.250 mm (0.2067 in) lifter is installed, and the measured clearance is 0.400 mm (0.0157 in). Replace the 5.250 mm (0.2067 in) lifter with a new No. 42 lifter.

  11. Standard exhaust valve clearance (cold): 0.38-0.48 mm (0.015-0.019 in).
  12. EXAMPLE: he 5.340 mm (0.2102 in) lifter is installed, and the measured clearance is 0.510 mm (0.020 in). Replace the 5.340 mm (0.2102 in.) lifter with a new No. 42 lifter.

  13. Install the selected valve lifter.
  14. Install the intake camshaft. Refer to Intake Camshaft and Valve Lifter Replacement.
  15. Install the exhaust camshaft. Refer to Exhaust Camshaft and Valve Lifter Replacement.
  16. Install the No. 1 chain tensioner.
  17. Install the cylinder head cover. Refer to Camshaft Cover Replacement.
  18. Install the spark plug. Refer to Spark Plug Replacement.
  19. Install the ignition coil assembly. Refer to Ignition Coil Replacement.
  20. Inspect for oil leak.
  21. Inspect the ignition timing.
  22. Install the engine cover. Refer to Engine Cover Replacement.
  23. Install the engine under right cover.