GM Service Manual Online
For 1990-2009 cars only

Inspect the following areas:

    • Inspect the valve rocker arms and ball at the mating surfaces. These surfaces should be smooth and free of scoring or other damage.
    • Inspect the valve rocker arms and the mating surfaces. These surfaces should be smooth and free of scoring or other damage.
    • Inspect the valve rocker arm valve pushrod sockets and valve stem mating surfaces. These surfaces should be smooth with no scoring or exceptional wear.
    • Inspect the valve pushrods for scored ends or bends.
    • Inspect the camshaft and crankshaft sprockets.
    • Inspect the key and crankshaft keyway for wear.
    • Inspect the crankshaft timing chain for binding.
        1. Set the J 8520 on zero.
        2. Slowly rotate the crankshaft until the valve pushrod is raised fully.
        3. Compare the total lift shown on the J 8520 with the specifications.
        4. Remove the J 8520 .