When to replace starter motor?
John turned the key, heard a loud click and ... nothing happened. He tried again and heard nothing this time.
The headlights and everything electrical seemed to work fine. The cause of the problem could be:
- a bad starter neutral switch;
- a bad key switch;
- a bad starter.
In most of the cases problems like described above a caused by a bad starter or starter solenoid.
How to check out a starter motor and its solenoid?
Starter motor problems occur because of the bad spots on the commutator which affects the contact with the brushes.
The brushes sometimes wear out but not normally. Open circuits can occur in the armature or in stator windings.
The recommended procedure is to replace the starter.
We diagnose the starter by measuring the current draw. To do this we crank the starter motor and watch the current.
If there is a high current draw then the starter is at fault.
Starter Motor Checking Procedure
When checking out a starter motor we remove it from the car and lock it firmly in a vice.
The following test can be done with the starter in the car but it makes it a bit more difficult and there is a chance of shorting out the test jumper cables to ground.
We connect the negative battery jumper cable to the vice that is holding the starter by the frame. The positive goes to the terminal on the solenoid.
Then we actuate the solenoid with jump from the big terminal to one of the smaller ones with a jumper wire or a screwdriver blade.
Silent starter motor in the test indicates that the starter motor is burned.
We might take it apart and see if it is worth fixing - new brushes, a clean-up of the commutator and possibly new windings.
Realistically and economically a replace of starter is recommended in this situation.
The new starter will have a new Bendix drive.