Why does the motor crank but fail to start the engine?

1 Answers
DiDamian
07/29/25 8:32pm
The reasons why the motor cranks but fails to start the engine: 1. Severe wear of starter carbon brushes; 2. Malfunction of starter control mechanism; 3. Damage to starter clutch. Severe wear of starter carbon brushes: The function of carbon brushes is to deliver current to the rotor, causing it to rotate. When the starter carbon brushes are severely worn, the symptom during startup is weak cranking, and it can be clearly observed through the belt and pulley that the crankshaft rotates very slowly. Malfunction of starter control mechanism: When the control mechanism fails, the pinion gear cannot engage with the flywheel ring gear, naturally preventing the engine from starting. The symptom is that when turning the key to start, only the sound of the starter rotating at high speed is heard without the sound of the engine crankshaft flywheel operating. Damage to starter clutch: After the clutch burns out, the rotor and pinion gear will slip relative to each other, causing the engine crankshaft flywheel to rotate very slowly or not at all.
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