Starter No Load Test

CAUTION:
^ Refer to Battery Disconnect Caution In Cautions and Notices.
^ Refer to SIR Handling Caution in Cautions and Notices.
^ When checking the solenoid while it is still on the starter motor, keep fingers, tools, and other objects away from the opening in the starter drive housing during the checks. The strong shifting action of the solenoid could cause personal injury or damage as the drive pinion moves into the position.




1. Secure the starter motor in a vise or a suitable test stand.
2. Turn OFF the carbon pile.
3. Open the switch.
4. Connect a voltmeter (3) from the starter motor terminal to the starter motor frame (ground).
5. Connect the starter motor and an ammeter (1) in series, from the positive terminal of a fully charged 12 volt battery.
6. Connect a switch from the S terminal (9) of the starter motor solenoid to the starter motor solenoid Bat terminal (10).

NOTE: Never operate the starter motor for more than 30 seconds at a time. Allow it to cool for at least 2 minutes. Overheating, caused by too much cranking, will damage the starter motor.

7. Close the switch.
8. Adjust the carbon pile load to obtain 10 volts on the voltmeter.
9. Note the following meter readings:
^ The armature speed on an RPM indicator.
^ The current draw on an ammeter.
10. Turn OFF carbon pile and open the switch.
11. Compare the measurements with the specifications. Refer to Starter Motor Usage. Electrical Specifications

The test results indicate the following conditions:
^ Rated current draw (amps) and rated no-load speed (RPM) indicate the normal condition of the starter motor.
^ Low, no load speed (RPM) and high current draw (amps) indicates too much friction, causing the armature to drag. This can result from any of the following conditions:
- Tight. dirty, or worn bushings or bearings
- A grounded or shorted armature
- Grounded fields
^ Failure to operate (no RPM). with high current draw (amps), indicates the following conditions:
- A direct short to ground in the starter terminal or in the fields.
- Seized bearings (This should have been determined by turning the armature by hand).
^ Failure to operate (no RPM), with low or no current draw (amps), indicates the following conditions:
- An open field circuit
- An open in the armature coils
- Broken brush springs
- Worn brushes
- High insulation between the commutator bars or other causes which would prevent contact between brushes and commutator.
^ Low, no load speed (RPM) and low current draw (amps), indicates a high internal resistance caused by the following conditions:
- Poor electrical connections
- Defective electrical leads
- Other causes listed under Failure to operate (no RPM), with low or no current draw (amps), above.
^ High, no load speed (RPM) and high current draw (amps) normally indicates shorted fields.