BEAM AS 4Z9426 - Caterpillar

Probable Causes
Lubrication
Valve train components
Valve lashRecommended Actions
Lubrication
Remove the valve mechanism cover. Refer to Disassembly and Assembly, "Valve Mechanism Cover - Remove and Install" for the correct procedure.
Crank the engine and check the lubrication in the valve compartment. Ensure that there is adequate engine oil flow in the valve compartment. The passages for the engine oil must be clean. Note: Do not run the engine without the valve mechanism cover.Valve Train Components
Inspect the following components of the valve train:
Rocker arms
Valve bridges
Pushrods
Valve lifters
Camshaft
Valve stems
Rocker shaft
Check the components for the following conditions: abnormal wear, excessive wear, straightness and cleanliness. If necessary, use new parts for replacement. Note: If the camshaft is replaced, new valve lifters must also be used.Valve Lash
Adjust the valve lash of the engine. Refer to Systems Operation, Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust" for the correct procedure.