Dirt → Clean with 600 grit sandpaper.
2. Measure: commutator diameter (a)
Out of specification → Replace the starter motor.
- Min. commutator diameter: 27 mm
3. Measure: mica undercut (a)
Out of specification → Scrape the mica to the proper measurement with a hacksaw blade which has been grounded to fit the commutator.
- Mica undercut: 0.7 mm
Note: The mica must be undercut to ensure proper operation of the commutator.
4. Measure: armature assembly resistances (commutator and insulation)
Out of specification → Replace the starter motor.
a. Measure the armature assembly resistances with the pocket tester.
- Pocket tester: 90890-03112
Armature assembly:
- Armature coil resistance (1): 0.026-0.034 Ω at 20°C
- Insulation resistance (2): Above 1 MΩ at 20°C
b. If any resistance is out of specification, replace the starter motor.
5. Measure: brush length (a)
Out of specification → Replace the brushes as a set.
- Min. brush length: 5 mm
6. Measure: brush spring force
Out of specification → Replace the brush springs as a set.
- Bruch spring force: 7.65-10.01 N (780-1020 g)
7. Check: gear teeth
Damage/wear → Replace the gear.
8. Check: oil seal
Damage/wear → Replace the defective part(-s).
