The abnormal noise in a car's alternator can be attributed to the following 6 reasons: 1. Loose fasteners: Vibration during engine operation causes certain components to loosen, resulting in impact sounds. For example, loose flywheel bolts or connecting rod bolts can cause abnormal noises. 2. Deformation or damage of individual components: Abnormal noises can occur due to deformation or damage of certain parts. Examples include knocking caused by a bent connecting rod, abnormal noises from broken valve springs, or a fractured crankshaft. 3. Improper assembly, adjustment, or repair: Incorrect assembly, adjustment, or repair can lead to improper clearance between components. For instance, excessively tight piston pin assembly or improperly adjusted valve clearance can cause abnormal noises. 4. Excessive clearance: Clearance is a critical indicator of automotive assembly quality. When lubrication, temperature, load, and speed are constant, abnormal noises become more pronounced as clearance increases. 5. Poor lubrication: Lubrication is essential for normal engine operation, enabling functions such as cooling, cleaning, sealing, and rust prevention. When clearance, temperature, load, and speed are constant, the thickness of the lubricating oil film depends on the pressure of the lubrication system and the quality of the lubricating oil. High-quality lubricating oil and appropriate pressure create a better oil film; the thicker the oil film, the less mechanical impact, reducing the likelihood of abnormal noises. If the oil film is too thin, wear increases, leading to clear and distinct abnormal noises. 6. Abnormal combustion: In gasoline engines, abnormal combustion such as knocking can occur if ignition timing is too early or too late.
