LINK AS 8X3122 - Caterpillar

Air Starting Motor
If the starting motor fails, the engine may not start in an emergency situation. A scheduled inspection of the starting motor is recommended.The starting motor pinion and the flywheel ring gear must be in good condition in order for the engine to start properly. The engine will not start if the starting motor pinion does not engage the flywheel ring gear. The teeth of the starting motor pinion and the flywheel ring gear can be damaged because of irregular engagement.Inspect the starting motor for proper operation. Listen for grinding when the engine is started. Inspect the teeth of the starting motor pinion and the flywheel ring gear. Look for patterns of wear on the teeth. Look for teeth that are broken or chipped. If damaged teeth are found, the starting motor pinion and the flywheel ring gear must be replaced.
Personal injury or death can result from improperly checking for a leak.Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death.If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.
Inspect all of the components in the air circuit for the starting motor. Inspect all of the air lines and connections for leaks. If damaged teeth are found, the air circuit for the starting motor must be examined in order to determine the cause of the problem.Electric Starting Motor
If the starting motor fails, the engine may not start in an emergency situation. A scheduled inspection of the starting motor is recommended.The starting motor pinion and the flywheel ring gear must be in good condition in order for the engine to start properly. The engine will not start if the starting motor pinion does not engage the flywheel ring gear. The teeth of the starting motor pinion and the flywheel ring gear can be damaged because of irregular engagement.Inspect the starting motor brushes and remove dust build-up from the starting motor every 2 years.Inspect the starting motor for proper operation. Listen for grinding when the engine is started. Inspect the teeth of the starting motor pinion and the flywheel ring gear. Look for patterns of wear on the teeth. Look for teeth that are broken or chipped. If damaged teeth are found, the starting motor pinion and the flywheel ring gear must be replaced.Problems with the electric starting motor can be caused by the following conditions: malfunction of the solenoid and malfunction of the electric starting system.Inspect the electrical system for the following conditions:
Loose connections
Corrosion
Wires that are worn or frayed
CleanlinessRemoval and Installation of the Starting Motor
Refer to the Service Manual, "Disassembly and Assembly" module for information on removing the starting motor and installing the starting motor.Consult your Caterpillar dealer for assistance and/or for options on replacement of the starting motor.