Testing the starting system - Starting system trouble shooting

Armature

Use a millimetre to check the insulation between the armature core and each segment which should be complete. The meter should also indicate continuity between each segment.

Any short circuit in the armature winding may be tested with a growler. If the short circuit is indicated, the winding has to be replaced.

Field coil

Continuity should exist in the field windings which may be tested with a millimeter. There should also be perfect insulation between the yoke and the field terminal.

Brushes

Examine the brushes visually for wear and damage. If the wear or damage is more than the permissible limits, replace the concerned brush.

Brush holders

Use a Multimeter to check the insulation between the positive brush holder and the holder frame. In case of deviation from complete insulation, rectify the fault suitably by repairing or replacing the damaged component.

Solenoid switch or shift

Disconnect the lead wire connecting the switch to the starter motor and apply battery voltage between the switch terminals. If correct, the plunger is attracted. In case of shift, the pinion would also project. It must be noted that the test should not be done continuously for more than 10-10 seconds.

Starting system troubleshooting

The common faults occurring in the starting system are described below, along with their possible causes and suitable remedies.

The starting motor does not operate

                To find out the specific cause for this trouble it is quite helpful if the car lights are turned on before an attempt is made to start cranking the motor. The lights will then be affected in different ways depending upon the cause of trouble, as soon as the starter key is operated:

Lights go off completely:

This is due to some loose connection in the circuit, most likely at the battery. This may be located and rectified accordingly.

Lights dim heavily:

In this case, the possible causes could be any or more of the following:

Weak battery: it may be checked and if found discharged may be removed for recharging.

The starting motor field or armature may be grounded. It may be checked using a circuit tester and rectified suitably.

The pinion of the Bendix drive may be jammed into engagement with the flywheel. This may be freed by placing the transmission in high gear and rocking the vehicle to and fro. If this action does not free the pinion, then loosen the mounting bolts of the starter motor, pull the motor slightly till the pinion is disengaged, and retighten the bolts.

There may be some defect in the engine, for instance, excessive friction, which may be properly tested.

Lights dim, but only slightly. The reasons for this may be the end-clearance for the pinion may not be sufficient, so that it reaches the end of its travel before the starting motor switch may be operated by the solenoid shift.

Lights remain unaffected. This means that the circuit is open somewhere. The wiring and the individual components have to be tested separately for open-circuit. Any component found defective has to be replaced.

The starting motor does operate, but slowly

The battery may be weak or defective. The same should be tested therefore and recharged or replaced with a new one depending upon the fault.

The starting motor may be defective: the field windings or the armature may be open or short-circuited. Or the commutator bars may be dirty or burnt. The motor should be tested thoroughly and repaired suitably as required.

The lubricating oil in the engine may be of viscosity, higher than the one prescribed. In such a situation, replace the oil with the one of proper specifications.

The sleeve or the pinion threads in the starting drive may be dirty and thus be sticking. The same should be cleaned thoroughly with kerosene oil.

The starting motor operates, but the engine is not cranked

Some components in the starting drive may be broken, which should be replaced.

The pinion gear may not be aligned properly which may be checked and rectified.

The overrunning clutch may be slipping, which should be replaced.

The teeth in the flywheel ring may be broken. The ring gear has to be replaced in such a case.

The starting drive does not disengage after the engine starts

The mounting bolts of the starting motor may be loose, which may be tightened.

The armature shaft may be bent, which may be straightened or replaced.

The circuit switches may be defective. They should be checked thoroughly. Any defective switch detected has to be replaced.

The pinion gear may not be aligned properly which should be thoroughly cleaned with kerosene oil.

There may be short-circuiting in the solenoid, which may be tested. If we found defective, that solenoid should be repaired or replaced.

The return spring of the shift lever may be very weak or even broken. In either case, the same has to be replaced with a new spring.

Noisy operation

The teeth or flywheel ring may have warmed out. The same has to be replaced.

The pinion spring may be broken, which has to be replaced.

Starter motor bearings may have worn out. These may be inspected and if required, replaced.

Lack of lubrication of the starting motor bearings may also be a source of undue noise.

The motor shaft may be bent, which may be checked and replaced if required.