Starter Motor: Testing and Inspection

NOTE: Do not use grease dissolving solvents for cleaning the overrunning clutch or armature. Solvents dissolve the grease packed in the clutch and damage the armature and the field coil insulation.

1. Clean all of the starter motor parts.
2. Test the drive components action.
3. Inspect that the pinion turns freely in the overrunning direction.
4. Inspect the pinion teeth for the following:
^ Chips
^ Cracks
^ Excessive wear
5. Inspect the ring gear teeth as badly chipped pinion teeth can indicate chipped ring gear teeth.
6. Inspect the drive components for slipping:
6.1. Wrap the armature with a shop towel.
6.2. Clamp the armature in a vise.
6.3. Install the socket on the pinion.
6.4. Turn the pinion counterclockwise. The clutch should not slip up to 68 Nm (50 lb ft) of torque.
6.5. Replace the drive components if slippage occurs up to 68 Nm (50 lb ft).
7. Wipe the drive components clean.
8. Do not lubricate the drive components.
9. Inspect the armature commutator.
10. Clean the commutator with 400 grit polishing cloth if the commutator is dirty.
11. Replace the armature if the commutator is rough.
12. Do not undercut or turn the commutators.
13. Inspect that there is a good connection between the armature conductors and the commutator bars.
14. Inspect the armature for short circuits:
^ Place the armature on a growler.
^ Hold a hacksaw blade over the armature core and rotate the armature.
^ The armature has a short if the blade vibrates.
^ Clean between the commutator bars.
^ Recheck the armature for short circuits.
^ Replace the armature if the hacksaw blade still vibrates.
15. Inspect the series coil for opens:
^ Using a self powered test lamp, place one lead on the field lead terminal.
^ Place the other lead on the insulated brush.
^ Repair or replace the series coil if the lamp fails to light.
^ Check each insulated brush to verify the brush to lead continuity.




16. Inspect the series coil for grounds:
^ Using a self powered test lamp, place one lead on the grounded brush
^ Place the other lead on an insulated brush holder
^ Repair or replace a grounded series coil if the test lamp lights.




17. Inspect the solenoid hold-in winding:
17.1. Connect an ammeter and switch in series with a 12-volt battery and the S terminal on the solenoid.
17.2. Connect a voltmeter to the S terminal and to the ground.
17.3. Connect a carbon pile across the battery.
17.4. Adjust the voltage to 10 volts.
17.5. Note the ammeter reading.
17.6. The starter motor reading should be 10 to 20 amperes.
18. Inspect both of the windings:
18.1. Connect the leads as indicated above in the previous test.
18.2. Ground the solenoid motor terminal M.
18.3. Adjust the voltage to 10 volts.
18.4. Note the armature readings.
18.5. The starter motor reading should be 60 to 85 amperes.
19. Current draw readings that are over specifications indicate the following:
^ Shorted turns
^ A ground in the solenoid windings
^ Replacement of the starter solenoid is needed.
20. Current draw readings that are under specifications indicate the following:
^ Excessive resistance
^ A zero reading indicates an open
^ Inspect and repair the connections if possible.
^ Replacement of the starter solenoid is needed if repair of the connections is not possible.
21. The starter solenoid is serviced as a unit.