Starter Motor: Testing and Inspection

CHECKING THE COMMUTATOR




1. Place the armature on a pair of V-blocks, and check the run-out by using a dial gauge.

Standard value: 0.05 mm (0.002 in.)
Limit: 0.1 mm (0.0039 in.)




2. Check the outer diameter of the commutator.

Standard value: 29.4 mm (1.157 in.)
Limit : 28.4 mm (1.118 in.)




3. Check the depth of the undercut between segments.
Standard value: 0.5 mm (0.020 in.)
Limit: 0.2 mm (0.0079 in.)

BRUSH HOLDER




Check for continuity between the brush holder plate and the brush holder.

The normal condition is no continuity.

OVERRUNNING CLUTCH



1. While holding clutch housing, rotate the pinion. Drive pinion should rotate smoothly in one direction, but should not rotate in opposite direction. If clutch does not function properly, replace overrunning clutch assembly.
2. Inspect pinion for wear or burrs. If pinion is worn or burred, replace overrunning clutch assembly. If pinion is damaged, also inspect ring gear for wear or burrs.

FRONT AND REAR BRACKET BUSHING
Inspect bushing for wear or burrs. If bushing is worn or burred, replace front bracket assembly or rear bracket assembly.

TESTING ARMATURE

TESTING ARMATURE FOR SHORT-CIRCUIT




1. Place armature in a growler.
2. Hold a thin steel blade parallel and just above while rotating armature slowly in growler. A shorted armature will cause blade to vibrate and be attracted to the core. Replace shorted armature.

TESTING ARMATURE FOR GROUNDING




Check the insulation between the armature coil cores and the commutator segments. They are normal if there is no continuity.

CHECKING FOR ARMATURE COIL WIRING DAMAGE/DISCONNECTION




Check for continuity between segments. The condition is normal if there is continuity.

CHECKING FOR OPERATION

MAGNETIC SWITCH PULL-IN TEST
1. Disconnect the field coil wire from the M-terminal of the magnetic switch.




2. Connect a 12V battery between the S-terminal and the M-terminal.

CAUTION: This test must be performed quickly (in less than 10 seconds) to prevent the coil from burning.

3. If the pinion moves out, then the pull-in coil is good. If it doesn't move out, replace the magnetic switch.

MAGNETIC SWITCH HOLD-IN TEST
1. Disconnect the field coil wire from the M-terminal of the magnetic switch.




2. Connect a 12V battery between the S-terminal and the body.

CAUTION: This test must be performed quickly (in less than 10 seconds) to prevent the coil from burning.

3. If the pinion moves out, everything is in order. If the pinion moves back and forth repeatedly the hold-in circuit is open. Then replace the magnetic switch.

FREE RUNNING TEST
1. Place the starter motor in a vise equipped with soft jaws and connect a fully-charged 12-volt battery to starter motor as follows:




2. Connect a test ammeter (100-ampere scale) and carbon pile rheostat as shown is the illustration.
3. Connect a voltmeter (15-volt scale) across starter motor.
4. Rotate carbon pile to the off position.
5. Connect battery cable from battery negative post to starter motor body.
6. Adjust until battery voltage shown on the voltmeter reads 11 volts.
7. Confirm that the maximum amperage is within the specifications and that the starter motor turns smoothly and freely:

Current : Max. 90 Amps
Speed : Min. 3,000 rpm

MAGNETIC SWITCH RETURN TEST
1. Disconnect field coil wire from the M-terminal of the magnetic switch.




2. Connect a 12V battery between M-terminal and the body.

NOTE: This test must be performed quickly (in less than 10 seconds) to prevent the coil from burning.

3. Pull pinion out and release. If pinion returns quickly to its original position, everything is in order. If it doesn't, replace the magnetic switch.