FINAL DRIVE GP 8G4170 - Caterpillar

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.
Note: Use of a platform may be necessary to reach the engine valve rotators.Perform this procedure after the valve lash has been set.Note: Ensure that the engine cannot be started except by the person performing the maintenance procedure. Install a "DO NOT OPERATE" tag near the starting mechanism.
Remove the covers for the valve mechanisms. Refer to the Disassembly and Assembly Manual, "Valve Cover - Remove and Install" for the procedure.
Mark the tops of the valve rotators with a permanent marker. Note the position of the marks.
Install the covers for the valve mechanisms. Refer to the Disassembly and Assembly Manual, "Valve Cover - Remove and Install" for the procedure.
Start the engine. Operate the engine for 5 minutes. Stop the engine.
Remove the covers for the valve mechanisms. Refer to the Disassembly and Assembly Manual, "Valve Cover - Remove and Install" for the procedure.
Observe the position of the marks that are on the valve rotators.
If any valve fails to rotate, consult your Cat dealer.
Install the covers for the valve mechanisms. Refer to the Disassembly and Assembly Manual, "Valve Cover - Remove and Install" for the procedure.