C27 Engine for the AD55B Underground Articulated Truck Engine Has Mechanical Noise (Knock) Caterpillar

Probable Cause

• Engine accessories

• Valve train components

• Stuck injector or faulty injector

• Connecting rod bearing

• Crankshaft bearings

Recommended Actions

Engine Accessories

Check for damaged engine accessories. Isolate the source of the noise. Remove the suspect engine accessories. Inspect the suspect engine accessories. Repair the engine accessories and/or replace the engine accessories.

Valve Train Components

1. Check for damage to valve train components. Remove the valve cover from the suspect cylinder(s). Check the following items for damage: camshaft, valve rotocoil, valve springs, camshaft followers, rocker shaft, bridges and injectors.

2. Check for valves that do not move freely. Remove the cylinder head and inspect the valves.

Replace any damaged parts. If damage has occurred, ensure that the following components are free of contamination: cylinder liner, piston and exhaust system. Replace any damaged parts.

Injectors

Perform an "Injector Solenoid Test" in order to confirm if the injectors are operating properly.

Connecting Rod Bearings

Inspect the connecting rod bearings and the crankshaft pins (journals) for scoring. Check the piston pin for excessive wear. Replace any damaged parts.

Crankshaft Bearings

Check main journals of the crankshaft and the main journal bearings for excessive wear. Replace any damaged parts.