What causes starter motor failure?

 Starter motor failure can occur due to various reasons. Here are some of the most common culprits:

Mechanical Wear and Tear
The internal mechanical components of a starter motor, such as the bearings, play a crucial role in its smooth operation. Over time, these parts can deteriorate. As the bearings start to go bad, increased friction makes it harder for the motor to turn. This means the motor demands more power to operate. Eventually, the reduced rotational speed becomes insufficient to start the engine.

Electrical Insulation Breakdown
The armature winding within the starter motor is insulated to ensure efficient electrical flow and torque generation. When the insulation on the armature winding starts to break down, the electrical current can leak or flow erratically. As a result, the starter motor loses its ability to produce the necessary torque. Even with a fully charged battery, it may struggle to turn the engine over.

Solenoid and Commutator Issues
A common symptom of starter motor problems is a clicking sound when you turn the key, with no subsequent engine rotation, despite a fully charged battery. In many cases, this points to issues with the solenoid or commutator. These components rely on clean and proper electrical connections to function. If the internal connections within the solenoid or commutator become worn out or contaminated with dirt and grime, their conductivity is compromised. This can lead to intermittent starting problems, like a starter that works fine in the morning but fails to crank after the vehicle has been driven and the components have warmed up.

The silver lining is that diagnosing a faulty starter motor is relatively straightforward. Once you've removed the starter from the car, most auto parts stores offer a convenient on - the - spot testing service. This allows you to quickly and accurately determine whether the starter motor is indeed the source of your vehicle's starting woes.