A car starter motor supplies the physical force necessary to start a car's engine. It performs a vital automotive function by engaging and spinning a car's engine flywheel. This function becomes all too apparent when a starter motor fails.
Car Won't Start
A bad starter motor is often the problem when a car's engine fails to turn. The car battery supplies the starter motor with the power to turn, or start, the engine. If the starter motor is faulty, it won't be able to utilise the power from the car battery, and the car won't start.
Many times a bad starter motor makes noise--clanking, clicking or grinding--when the ignition key is turned and the starter is engaged. This type of starter noise is normally indicative of a starter motor that is worn and about to fail.
Starter Solenoid Dysfunction
A starter solenoid, which is a small mechanical attachment on top of a starter motor housing, engages and disengages the starter gear with the engine flywheel. The starter solenoid can wear out or fail, rendering the starter motor (which may still be functioning) ineffective.
A burnt smell and/or smoke coming from a starter motor is indicative of an electrical problem with the wires and connections within a starter motor. Battery power is carried directly to a starter motor via a series of small electrical wires that attach directly to the starter solenoid. Any problem with these wires can cause a short, which can cause a burnt smell and/or smoke.
Non-Retracting Starter Gear
After a car's ignition system is activated and the starter motor engages with the engine flywheel, the starter gear is supposed to retract to its original "non-activated" position after a car starts running. A starter gear that does not retract is a sign that a starter motor is bad and needs to be replaced.