Starter motor maintenance is important for starting the engine properly. In this article, I will discuss the starter motor maintenance tips and inspection details.
Starter Motor Maintenance
> In the event that the starter motor fails to crank the engine at a high engine speed to allow it to start, first, check the state of charge of the battery, tightness, cleanliness, and all the heavy-duty electric joints.
> This usually solves most of the starting problems. If the slow speed cranking still persists or the starter motor fails to function at all, it is necessary to remove the unit from the engine.
> After its removal from the engine, a simple functional check can be made on the solenoid switch and the motor separately.
> To check the solenoid, connect one lead from a 12 V battery to the supply terminal and the other battery lead to the body of the starter. This should cause the starter drive to move along the armature shaft.
> If an armature is put in series with the solenoid and a connection is also made between the solenoid terminal and the top main terminal, then with 12 V applied, the armature should read approximately 20A.
A high current reading(20A) or failure of the drive to move at all, means the solenoid is faulty and should be returned to a recognized service center for rectification or replacement. A direct light run check can also be made on the starter at this time.
The starter motor should rotate freely at 5000-7000 R.P.M., and take a maximum current of 100A. If the motor fails to rotate, is slugging, or takes a high current, it should be returned to its place.
Starter Motor Maintenance for Commercial Vehicles.
Two different types of electric starter motors are used for commercial vehicles, namely the non-axial starter and the Axial Starter. Usually, these are similar in regard to certain electrical details, like the armature and brush gear, so the general information on their maintenance is applicable for such items for both types.
Non-axial Starter Motor Maintenance
Provided that reasonable care is taken when operating this type of starting motor, it will give trouble-free performance over a long period. When mounted on the engine, there should be a pitch clearance of at least 0.38 mm to 0.63 mm. Further, it should be possible to withdraw the commutator end cover and inspect the brushes without removing the starter from the engine.
> The brushes should be inspected at regular intervals, and they should always be free in their guides, with their flex leads quite clear for movement. When special fiber insulation is provided for the brush flexes, it should be examined for charring, a cause of short circuits.
> The positive and negative brushes must be insulated from one another. They can be tested by means of a lamp as used for testing field coils and other insulation. The brushes need only be lifted from the commutator for this test.
> The brushes when fitted to a motor should be well bedded down. If not, wrap a strip of very fine glass or carborundum paper firmly around the commutator and with the brush in position. Rotate the armature by hand in the proper working direction of rotation until the correct brush shape is obtained. The brushes on a motor should not wear down so that the trigger or spring is not giving effective pressure.
> The brush spring pressure value is important. It should be tested by means of a spring balanced hooked under the spring trigger or spring tips. Its value for the various types of axial starter motors is given in the maintenance catalogs of the manufacturers.
Axial Starter Motor Maintenance
> Make sure all the engine controls are correctly adjusted. Release the switch as soon as the engine starts.
> If the engine does not start at once, allow it to come to rest before pressing the starter switch again.
> Do not use it continuously if the engine does not start. Ascertain the cause of failure. With some engines, it is often helpful to depress the clutch when starting. On no account should it be operated while the engine is running, otherwise serious damage is likely to occur to both starter and flywheel teeth.
Conclusion
The starter motor should be inspected by an experienced technician. Regular servicing can help the starter motor to operate perfectly in every condition.