Checks

CHECKS

The starter motor components should be subjected to the tests listed below:

rotor: contintuity test, short circuit and insulation to earth
stator: continuity test and insulation to earth
brush holder support: insulation to earth
solenoid valve: continuity test and insulation to earth

Each time the starter motor makes noises during starting, the pinion/free wheel must be replaced.

STARTER MOTOR OPERATIONAL FAULT DIAGNOSIS

1. The motor does not rotate

The cause may be:

• the battery terminals are oxidized;
• starter motor supply cable terminal slack;
• starter motor supply cable terminal broken or oxidized;
• battery completely discharged;
• lack of contact for rotor arms at commutator;
• positive rotor arm short circuited;
• starter switch contacts oxidized, worn or insulated through fragments;
• rotor or inductor to earth;
• rotor or commutator centrifuged;
• pinion engagement solenoid winding broken or to earth.

2. The motor rotates very slowly

The cause may be:

• commutator brushes and blades worn;
• part of inductor or rotor winding coils short circuited;
• battery terminals oxidized;
• battery state of charge very low or one or more elements deteriorated.

3. Excessive noise during starting

The cause may be:

• pinion free wheel mechanism worn;
• poor alignment between motor and flywheel ring gear;
• several flywheel ring gear teeth excessively worn on the engagement side;
• speed reduction gear defective or excessively worn.