GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 26900-1 Outside Micrometer

Important: 

   • Valve clearance measurement should only be done on a cold engine.
   • To change the valve clearance on a given valve, the lifter must be replaced by one that is thicker or thinner in size.
   • Lifters are available in 35 different sizes, in increments of 0.020 mm (0.0008 in).
   •  Lifters range in size from 5.060 mm (0.1992 in) to 5.740 mm (0.2260 in).

    Caution: Refer to Battery Disconnect Caution in the Preface section.

  1. Disconnect the negative battery cable.
  2. Remove the cylinder head cover. Refer to Cylinder Head Cover Replacement .

  3. Object Number: 234055  Size: SH
  4. Turn the crankshaft clockwise until the alignment notch on the crankshaft pulley is aligned with the "0" mark on the engine front cover tab.

  5. Object Number: 625507  Size: SH
  6. Check that the point marks on the camshaft gears are aligned. If the point marks on the camshaft gears are not aligned, turn the crankshaft clockwise one revolution in order to align the camshaft gears.

  7. Object Number: 234066  Size: SH
  8. Using a feeler gage, measure the clearance between the intake valve lifters and the intake camshaft for cylinders #1, and #2.
  9. Intake Valve Clearance (Cold):
    0.15-0.25 mm (0.006-0.010 in)

    Important: Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

  10. Using a feeler gage, measure the clearance between the exhaust valve lifters and the exhaust camshaft for cylinders #1, and #3.
  11. Exhaust Valve Clearance (Cold):
    0.25-0.35 mm (0.010-0.014 in)

    Important: Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

  12. Turn the crankshaft clockwise 1 revolution until the alignment notch on the crankshaft pulley is aligned with the "0" mark on the engine front cover tab.

  13. Object Number: 234070  Size: SH
  14. Using a feeler gage, measure the clearance between the intake valve lifters and the intake camshaft for cylinders #3, and #4.
  15. Intake Valve Clearance (Cold):
    0.15-0.25 mm (0.006-0.010 in)

    Important: Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

  16. Using a feeler gage, measure the clearance between the exhaust valve lifters and the exhaust camshaft for cylinders #2, and #4.
  17. Exhaust Valve Clearance (Cold):
    0.25-0.35 mm (0.010-0.014 in)

    Important: Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

  18. If there were any valve clearances that were out of specifications, the camshaft(s) must be removed in order to replace the lifter(s). To remove the intake camshaft, refer to Intake Camshaft and Valve Lifter Replacement or to remove the exhaust camshaft, refer to Exhaust Camshaft and Valve Lifter Replacement .

Lifter Selection

Important: In order to maintain the specified valve clearance the proper lifter must be selected. Perform the following procedure in order to select the proper lifter:

  1. Determine the valve(s) clearances that were out of specifications.
  2. Remove the lifter(s) from the lifter bores of the out of specification valves.

  3. Object Number: 234082  Size: SH
  4. Use a J 26900-1 to measure the thickness of the removed lifter.
  5. After measuring the lifter, refer to the record of the out of specification valve clearances.
  6. After determining the two measurements, select the proper lifter thickness for the required valve clearance.
  7. After selecting the proper lifter, the camshaft must be re-installed and the valve clearance re-measured. To install the intake camshaft, refer to Intake Camshaft and Valve Lifter Replacement or to install the exhaust camshaft, refer to Exhaust Camshaft and Valve Lifter Replacement .
  8. After confirming the valve clearance is correct for all valves, re-assemble the timing chain and timing chain housing. Refer to the installation instructions in Timing Chain and Sprocket Replacement .
  9. Install the cylinder head cover. Refer to the installation instructions in Cylinder Head Cover Replacement .
  10. Notice: Refer to Fastener Notice in the Preface section.

  11. Connect the negative battery cable.
  12. Tighten
    Tighten the bolt to 15 N·m (11 lb ft).