What Causes the Car Starter Motor to Not Respond?

[McAlejandro]

Here are the specific reasons why a car starter motor may not respond: 1. Severe wear of starter carbon brushes: The symptom during startup is weak cranking, where the crankshaft rotation is visibly slow through the belt and pulley. When the wear is extremely severe, the starter cannot rotate the crankshaft at all, producing only an electric current sound. 2. Fault in the starter control mechanism: Apart from the starter motor, the starter assembly includes an electromagnetic control mechanism. When this mechanism fails, the pinion gear cannot engage with the flywheel gear, preventing engine startup. The symptom is turning the ignition key and hearing only the high-speed rotation sound of the starter without the sound of the engine crankshaft flywheel operating. 3. Damage to the starter clutch: Typically, the starter operates at around 120r/min, while the engine idles at approximately 900r/min after starting. The clutch prevents the engine from driving the starter if the driver fails to release the key promptly after startup, keeping the pinion and flywheel gears engaged, which could lead to starter burnout.