Starter motor's

Starter motor bench testing and repair.

In this exercise we first have to do a no load bench test to determine that the starter motor is working before we begin. The starter that we used for this no load test resulted in a voltage of 11.20v the minimum specification for voltage is no less than 11v, the current of this starter on the no load test is 56.1Amps the specifications for this test is 30-50Amps the result is just slightly out of the range but acceptable.

Next we proceed to disassemble the starter motor, after disassembling the starter we visually inspect the armature first for overheating; there appears to be no overheating.

Next we check the armature for signs of burning; there appears to be no burning on the armature.

Then we inspect the armature for signs of physical damage; there appears to be no sign of any physical damage on the armature.

finally we check for polling; there is no visual sign of unnatural polling on this armature, this concludes that visually the armature appears to be in good condition.

We then test for a ground circuit on the armature, we receive a infinity reading from the armature which is the specification.

Now we test for continuity circuit the specification for this is between 0 and 1 Ohms we recorded 0.7Ohms which is within the specification.

The next test is measuring the diameter of the commutator the minimum diameter is between 26.8mm and 31mm, we recorded a result of 30mm which is within the specifications,

the mica undercut specifications is between 0.7mm and 1mm we recorded a 0.7mm result which passes the mica under cut.

Next we tested the armature shaft for run-out to do this we place the armature between 2 "V" blocks then turn it 360 degrees while reading the dial test indicator set up on the armature core.

The specifications for this are 0.0mm to 0.2mm we recorded a result of 0.1mm which is within the specifications.

the alternate method for testing the armature for continuity and ground circuit is to use a 48volt test light.

To do the continuity test you keep one of the probes on 1 segment and move the other probe around each of the segments, the test light should glow in this test to indicate a pass result.

For the ground test you place one probe on any commutator segment and the other on either the armature core or shaft for a pass result the light should NOT  glow.

Our armature recorded the result of a pass for both tests.

Next is an internal short circuit test, for this we first place our armature on the "V" of the growler then we turn the switch on to the growler position, now we hold a hacksaw blade along the armature and rotate the armature, the hacksaw blade didn't vibrate when the armature was rotated indicating that there is no short circuit.

Next we do visual checks on the field coils and pole shoes, first we check for signs of overheating; there are no signs of overheating on the field coils or pole shoes.

Next we check for signs of burning; we determine that there are no signs visually of any burning on the pole shoes or field coils.

Then we check for signs of physical damage; on our field coils  and pole shoes there is no sign of physical damage.

Lastly we check for signs of poling; there does not visually appear to be any sign of unnatural poling on our pole shoes or field coils.

Next we test the field coils for continuity for this test the specifications are between 0 to 0.02 Ohms. we recorded a result of 0.02 Ohms which is within the specifications.

Next we test the field coils for grounding the specification for this is an infinity result, when we tested our field coils we recorded an infinity result.

Now we test the brushes of the starter motor the specifications for this are a minimum length of 5mm for our brushes we recorded; brush 1 at 15mm, brush 2 at 20mm and brush 3 at 14mm.

Then we test the brush holder assembly, for this test  the specifications are infinity upon testing we recorded an infinity result.

This is a pull in winding test for this we we connect a 9v power supply between the ignition and starter motor  supply, the specifications for this test are between 8-12Amps we recorded a reading of 12Amps and witnessed a pull-in action from the plunger.

Next we do a hold in test the specifications for this are 5-8Amps on this test we recorded a result of 8Amps and witnessed the plunger remaining in until the power is disconnected.

Now we visually inspect the pinion gear, bushes and the clutch. to do this with the pinion gear we check it for damage and smooth movement along the armature shaft, there appears to be no damage to the pinion gear and the movement is smooth giving us a pass result. Next we check the bushes by inserting the end of the armature shaft into the end housing and check for bush clearance, the bushes have clearance and no sign of physical damage giving a pass result. Finally we check the clutch to do this we turn the pinion gear  in the direction of the motor rotation, the clutch was free wheeling wich indicates it is working correctly.

After re-assembling the starter motor we test it again for a final no-load test, the voltage specifications are no less than 11 volts, we recorded a result of 11.70v for the no-load test the specifications for the current should be between 30-50Amps we recorded a result of 54.1Amps which is just slightly out of the range but acceptable.

We used a mitsubishi starter motor. Model number 30281 for these test.