GM Service Manual Online
For 1990-2009 cars only

Inspect the following areas:

    • Inspect the valve lifter and valve stem tip mating surfaces. These surfaces should be smooth and free of scoring or other damage.
    • Inspect the valve lifters for scoring where it contacts the camshaft.
    • Inspect the camshaft journals, lobes, and camshaft housing bores for wear or scoring.
    • Timing chain for teeth that are no longer concentric
    • The camshaft gears and mating surfaces for damage or signs of movement
    • The key and crankshaft keyway for wear
    • The timing chain for binding or excessive wear