HEAD 6J5668 - Caterpillar

Probable Causes
Engine shutdown switch
Battery cables
Batteries
Starting circuit
Starting motor solenoid
Starting motor
Flywheel ring gear
Driven equipment
Engine accessories
Hydraulic cylinder lock
Internal engine problemRecommended Actions
Engine Shutdown Switch
Verify that the engine shutdown switch is in the OFF position. If the switch is in the ON position, fuel injection is disabled. Some engine shutdown devices will prevent the engine from being cranked.Battery Cables and/or Batteries
Inspect the battery disconnect switch, bus bars, battery posts, and battery cables for loose connections and corrosion. If the battery cables are corroded, remove the battery cables and clean the battery cables. Tighten any loose connections.
Inspect the batteries.
Charge the batteries. Refer to Special Instruction, SEHS7633, "Battery Test Procedure".
Load test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries".Starting Motor Solenoid and/or Starting Circuit
Test the operation of the starting motor solenoid.
Check the wiring to the starting motor solenoid.Starting Motor and/or Flywheel Ring Gear
Test the operation of the starting motor.
Inspect the starter pinion and the flywheel ring gear for damage. Ensure that the pinion gear does not bind with the flywheel ring gear during starting.Driven Equipment and/or Engine Accessories
Ensure free movement of the driveline.
Ensure that the timing pin was not left in the flywheel housing.
Remove any engine accessories that may lock up the engine. Inspect the condition of the accessories.The following list illustrates examples of engine accessories that may lock up the engine:
Fuel transfer pump
Air compressor
Engine oil pumpHydraulic Cylinder Lock
Check for fluid in the cylinders (hydraulic cylinder lock) by removing the individual unit injectors.Note: Be sure to drain the fuel from the cylinder head prior to removing the injectors. Fuel will flow from the cylinder head into the cylinders when the unit injector is removed.Internal Engine Problem
Inspect the internal components for the following conditions:
Seizure
Broken components
Bent components