GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 7872 Magnetic Base Dial Indicator Set
    • J 26900-5 Vernier Caliper
    • J 26900-2 Combimike Micrometer

Rocker Arm Shaft Inspection


    Object Number: 262371  Size: SH
  1. Place the rocker arm shaft in two V-Blocks and use a dial indicator to measure the runout of the rocker arm shaft.
  2. Rocker Arm Shaft Runout
    Maximum Runout = 0.20 mm (0.008 in)

  3. If the measured runout exceeds the specifications, replace the rocker arm shaft.

Rocker Arm Inspection


    Object Number: 262362  Size: SH
  1. Inspect the tips and cam-riding face (3) of the rocker arms for excessive wear.
  2. Replace any rocker arm that shows excessive wear.

Rocker Arm-to-Rocker Arm Shaft Clearance Inspection


    Object Number: 262326  Size: SH
  1. Using an outside micrometer, measure the diameter of the rocker arm shaft.
  2. Standard Rocker Arm Shaft Diameter
    15.969-15.984 mm (0.6287-0.6293 in)

  3. Using a Vernier caliper, measure the inside diameter of the rocker arm.
  4. Standard Rocker Arm Inside Diameter
    15.985-16.005 mm (0.629-0.630 in)

  5. Subtract the rocker arm inside diameter from the rocker arm shaft outside diameter and this will determine the rocker arm-to-rocker arm shaft clearance.
  6. Standard Rocker Arm-to-Rocker Arm Shaft Clearance
    0.001-0.036 mm (0.0001-0.0014 in)

  7. If the measured clearance exceeds the specifications, replace the rocker arm components as necessary.