Starter Motor: Testing and Inspection

INSPECTION

1. ARMATURE
1. Check commutator for any sign of burns of rough surfaces or stepped wear. If wear is of a minor nature, correct it by using sand paper.




2. Run-out test
Check the commutator run-out and replace if it exceeds the limit.




3. Depth of segment mold. Check the depth of segment mold.




4. Armature short-circuit test
Check armature for short-circuit by placing it on growler tester. Hold a hacksaw blade against armature core while slowly rotating armature. A short-circuited armature will cause the blade to vibrate and to be attracted to core. If the hacksaw blade is attracted or vibrates, the armature, which is short-circuited, must be replaced or repaired.




5. Armature ground test
Using circuit tester, touch one probe to the commutator segment and the other to shaft. There should be resistance of 1 MOhm or more. If resistance is 1 Ohm or less, armature is grounded. Replace armature if it is grounded.




2. YOKE
Make sure pole is set in position.




3. OVERRUNNING CLUTCH
Inspect teeth of pinion for wear and damage.
Replace if it is damaged. Rotate pinion in direction of rotation (clockwise). It should rotate smoothly. But in opposite direction, it should be locked.

CAUTION: Do not clean overrunning clutch with oil to prevent grease from flowing out.

4. BRUSH AND BRUSH HOLDER




1. Brush length
Measure the brush length and replace if it exceeds the service limit.
Replace if abnormal wear or cracks are noticed.


2. Brush movement
Be sure brush moves smoothly inside brush holder.




3. Insulation resistance of brush holder
Be sure there is resistance of 1 MOhm or more between brush holder and its plate.

5. MAGNETIC SWITCH

CAUTION:
- The following magnetic switch tests should be performed with specified voltage applied.
- Each test should be conducted within 3 to 5 seconds. Power to be furnished should be one-half the rated voltage.




6. SWITCH ASSEMBLY
Be sure there is resistance of 1 Ohm or less between terminals S and M, and between terminal S and ground. Use a circuit tester (set in "ohm"). Also check to be sure resistance is 1 MOhm or more between terminal M and B.