Valve Clean and Inspect

Important: Excessive valve stem to guide clearance may cause a noisy valve train, premature valve stem oil seal wear, component damage, and/or excessive oil consumption. Insufficient valve stem to guide clearance will result in noisy or sticking valves. Valves that are too tight may disturb engine smoothness or lead to component damage.

1. Inspect for excessive valve stem (1) to guide (2) clearance.

Important: Do not scratch the valve stem with the wire brush.

2. Clean the valves of carbon, oil and varnish. Carbon can be removed with a wire brush, varnish can be removed by soaking in Parts Immersion Solvent GM P/N 12345368 or equivalent.
3. Clean the deposits from the valve face.





4. Inspect the valve face for the following:
^ Worn or no margin (4, 1)
^ Pitting (2)
^ Burnt or eroded areas (3)
^ Grooving
^ Deposits
5. If any of the above conditions exist, replace the valve.
6. Clean the valve guides with a rifle brush and a suitable solvent.





7. Inspect the valves for the following:
^ Burnt or eroded areas (1)
^ A worn margin (2)
^ A bent stem (3)
^ A worn or scored stem (4)
^ A worn or chipped valve keeper groove (5)
^ A worn stem end (6)
^ A bent valve head
8. If the valves are worn or damaged replace the valve.
9. Burrs and minor scratches on the valve stem may be removed with an oil stone.
10. The valve stem end may be reconditioned by grinding. Follow the grinder manufacturer's instructions.
11. If the valve face had pieces broken off, inspect the corresponding piston and cylinder head area for damage.
12. The valves may be lightly lapped to the valve seats.