RA1.2, R1.4, R2.0, R2.2, R2.5, R2.7, R3.0, R4.5 and R5.5 Series Reduction Starting Motors Caterpillar

Troubleshooting can be difficult. Possible problems are in the following list. To make a repair to a problem, refer to the probable cause. This list of problems and probable causes will only give an indication of the location of a possible problem and the repairs that are needed. Sometimes additional work or other repairs are needed beyond the recommendations in the list. Remember that a problem is not normally caused by one part, but by the relation of one part with other parts. This list cannot give all possible problems and probable causes. The technician must find the problem and the source of the problem. Then make the necessary repairs.

Problem List

1. The starting motor does not turn or the starting motor turns too slowly.

2. The armature turns, but the pinion does not engage the flywheel ring gear.

3. The armature turns. The pinion engages the ring gear, but the engine does not crank.

4. The starting motor continues to run after the key start switch has been released.

5. The pinion does not disengage after the engine starts to run.

Problems

The starting motor does not turn or the starting motor turns too slowly.

Probable Causes:

1. The battery is discharged: The battery needs to be charged.

2. The battery is damaged: The battery needs to be replaced.

3. The battery cable terminals are loose. The terminals are corroded or the terminals have a poor ground connection: Tighten the cable terminals. Clean the terminals and the battery posts. Apply anti-acid grease to the battery posts.

4. The solenoid contacts are burnt or worn out: Replace the solenoid (switch).

5. The solenoid windings are disconnected or the solenoid windings are short circuited: Replace the solenoid (switch).

6. The key start switch, the solenoid, or the relay (if equipped) are damaged: As needed, replace the ignition, the key start switch, the solenoid, or the relay.

7. There is an excessive voltage drop in the cables. The cables may be damaged. There are loose cable connections, or there are corroded terminal connections: Check the starting motor cables and the cable connections.

8. The brushes are worn or shorted: Replace the brush holder and/or starting motor case.

9. The commutator is worn: Undercut the mica.

10. The field winding is shorted or grounded: Replace the case of the starting motor.

11. The armature winding is shorted or grounded: Replace the armature.

12. Not enough brush spring tension: Check the tension of the brush spring. If necessary, replace the springs.

13. There is a poor contact between the solenoid and the field winding: Repair connections.

14. The armature makes contact with the field winding because of a worn bearing or a bent armature: Replace the bearing or the armature.

15. The overrunning clutch is damaged: Replace the overrunning clutch.

The armature turns, but the pinion does not engage the flywheel ring gear.

Probable Causes:

1. The overrunning clutch is damaged or the pinion teeth are worn: Replace the overrunning clutch.

2. The overrunning clutch does not move freely on the splines of the solenoid: Remove the dirt and/or foreign material on the solenoid splines.

3. The flywheel ring gear is damaged: Replace the flywheel ring gear.

4. The solenoid is damaged or broken: Replace the solenoid.

5. The armature, the idler, or the clutch gear is damaged or broken: As needed, replace the armature, the idler gear, or the overrunning clutch.

The engine will not crank even though the pinion engages the ring gear and the armature rotates.

Probable Causes:

1. The battery is low: Charge the battery.

2. Not enough brush spring tension: Check the tension of the brush spring. If necessary, replace the springs.

3. The relay that is mounted away from the starting motor (if equipped) is damaged: Replace the relay.

4. There is an excessive voltage drop in the cables: Check the cables and the cable connections.

5. The overrunning clutch slips: Replace the overrunning clutch.

The starting motor continues to run after the key start switch has been released.

Probable Cause:

1. The key start switch, the solenoid, or the relay is damaged. As needed, replace the key start switch, the solenoid, or the relay.

The pinion does not disengage after the engine starts to run.

Probable Causes:

1. The solenoid return spring is weak or broken: Replace the solenoid.

2. The key start switch or the relay is damaged: Replace the key start switch or the relay.