EDGE AS 2937844 - Caterpillar

When inspecting the valve rotators, protective glasses or face shield and protective clothing must be worn, to help prevent being burned by hot oil or spray.
A valve rotator which does not operate properly will accelerate valve face wear and valve seat wear and shorten valve life. If a damaged rotator is not replaced, valve face guttering could result and cause pieces of the valve to fall into the cylinder. This can cause piston and cylinder head damage.
Engine valve rotators rotate the valves when the engine runs. This rotation deters deposits from building up on the valves and the valve seats.Perform the following steps after the engine valve lash is set, but before the valve covers are installed:
Start the engine and operate the engine at low idle.
Observe the top surface of each valve rotator. The valve rotators should turn slightly when the valves close. If a valve fails to rotate, consult your Cat dealer.