When the valves are constantly noisy, check for the following, as necessary:
- Unadjusted valve lash.
- Valve springs may be broken.
- Pushrods may be bent.
- Camshaft lobes may be excessively worn.
- Dirty or worn valve lifters.
- Valve guides may be worn.
- Valve seat or face runout may be excessive.
- Loose rocker arm studs.