Valves Cleaning and Inspection
1. Remove carbon from valve face, head, and stem (Figure 2). Valve stems should be lightly polished with an
extremely fine abrasive cloth. Remove carbon deposits only.
Figure 2. Cleaning Carbon from Valve.
2. Place straightedge across valve head and check for "dishing" (Figure 3). Any valves that are dished must be
discarded. (A narrow margin is common cause of dishing, therefore discard any valve that cannot be
satisfactorily refaced with specified margin (50 percent of a new valve).
Figure 3. Dished Valve Head.