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.
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