KIT-ACTUATOR 4478006 - Caterpillar

Probable Causes
Accessory equipment
Valve train components
Pistons
Connecting rod and main bearingsRecommended Actions
Accessory Equipment
Isolate the source of the noise. Remove any suspect engine accessory. Inspect the suspect engine accessory. Repair the engine accessory and/or replace the engine accessory if any defects are found.
If the mechanical noise is still apparent, refer to "Valve Train Components".Valve Train Components
Check the hydraulic lifters for correct operation. Refer to Systems Operation, Testing, and Adjusting, "Engine Valve Lash - Inspect".
Inspect the following components of the valve train. Refer to Disassembly and Assembly for any components that must be removed for inspection.
Rocker arms
Valve bridges
Pushrods
Hydraulic 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.
If the mechanical noise is still apparent, refer to "Pistons".Pistons
Inspect the pistons for damage and wear. Replace any damaged parts.
If the mechanical noise is still apparent, refer to "Connecting Rod and Main Bearings".Connecting Rod and Main Bearings
Inspect the connecting rod and main bearings. Also, inspect the bearing surfaces (journals) on the crankshaft. Replace any damaged parts.If the fault is still apparent, refer to Troubleshooting, "Cylinder Is Noisy".