Starter Motor: Testing and Inspection
INSPECTION1. INSPECT ARMATURE COIL
a. Check the commutator for open circuit.
Using an ohmmeter, check that there is continuity between the segments of the commutator.
If there is no continuity between any segment, replace the armature.
b. Check the commutator for ground.
Using an ohmmeter, check that there is no continuity between the commutator and armature coil core.
If there is continuity, replace the armature.
2. INSPECT COMMUTATOR
a. Check the commutator for the dirty and burnt surfaces.
If the surface is dirty or burnt, correct it with sandpaper (No.400) or on a lathe.
b. Check the commutator circle runout.
1. Place the commutator on V-blocks.
2. Using a dial gauge, measure the circle runout.
Maximum circle runout: 0.05 mm (0.0020 in.)
If the circle runout is greater than maximum, correct it on a lathe.
c. Using vernier calipers, measure the commutator diameter.
Standard diameter: 35.0 mm (1.378 in.)
Minimum diameter: 34.0 mm (1.339 in.)
If the diameter is less than minimum, replace the armature.
d. Check that the undercut depth is clean and free of foreign materials. Smooth out the edge.
Standard undercut depth: 0.7 mm (0.028 in.)
Minimum undercut depth: 0.2 mm (0.008 in.)
If the undercut depth is less than minimum, correct it with a hacksaw blade.
3. INSPECT FIELD FRAME
a. Check the field coil for open circuit.
Using an ohmmeter, check that there is continuity between the lead wire and field coil brush lead.
If there is no continuity, replace the filed frame.
b. Check the shunt coil for open circuit.
Using an ohmmeter, measure the resistance between shunt coil terminals A and B.
Resistance: 1.5 - 1.9 ohms at 20°C (68°F)
If the resistance is not as specified, replace the field frame.
4. INSPECT BRUSHES
Using vernier calipers, measure the brush length.
Standard length: 15.0 mm (0.591 in.)
Minimum length: 9.0 mm (0.354 in.)
If the length is less than minimum, replace the brush holder and field frame
5. INSPECT BRUSH SPRINGS
Check the brush spring load.
Take the pull scale reading the instant the brush spring separates from the brush.
Standard spring installed load:
21.5 - 27.5 N (2.2 - 2.8 kgf, 4.9 - 6.2 lbf)
Minimum spring installed load:
12.7 N (1.3 kgf, 2.9 lbf)
If the installed load is less than minimum, replace the brush springs.
6. INSPECT BRUSH HOLDER
Check the brush holder insulation.
Using an ohmmeter, check that there is no continuity between the positive (+) and negative (-) brush holders.
If there is continuity, repair or replace the brush holder.
7. INSPECT CLUTCH AND GEARS
a. Check the gear teeth on the pinion gear, idle gear and clutch assembly for wear or damage.
If damaged, replace the gear or clutch assembly.
If damaged, also check the ring gear of the flywheel for wear or damage.
b. Check the clutch pinion gear.
Hold the starter clutch and rotate the pinion gear clockwise, and check that it turns freely. Try to rotate the pinion gear counterclockwise and check that it locks.
If necessary, replace the clutch assembly.
8. INSPECT BEARINGS
Turn the bearing by hand while applying inward force.
If resistance is felt or the bearing sticks, replace the bearing.
9. INSPECT MAGNETIC SWITCH
a. Check the pull-in coil for open circuit.
Using an ohmmeter, check that there is continuity between terminals 50 and C.
If there is no continuity, replace the magnetic switch.
b. Check the hold-in coil for open circuit.
Using an ohmmeter, check that there is continuity between terminal 50 and the switch body.
If there is no continuity, replace the magnetic switch.
TEST
NOTE: These tests must be performed within 3 to 5 seconds to avoid during out the coil.
1. PERFORM PULL-IN TEST
a. Disconnect the field coil lead wire from terminal C.
b. Connect the battery to the magnetic switch as shown. Check that the clutch pinion gear moves outward.
2. PERFORM HOLD-IN TEST
With battery connected as above with the clutch pinion gear out, disconnect the negative (-) lead from terminal C. Check that the pinion gear remains out.
3. INSPECT CLUTCH PINION GEAR RETURN
Disconnect the negative (-) lead from the switch body. Check that the clutch pinion gear returns inward.
4. PERFORM NO-LOAD PERFORMANCE TEST
a. Connect the battery and ammeter to the starter as shown.
b. Check that the starter rotates smoothly and steadily with the pinion gear moving out. Check that the ammeter shows the specified current.
Specified current: 100 A or less at 11.5 V