What are the causes of abnormal noise in a car alternator?
2 Answers
Car alternator abnormal noise is caused by: 1. Slipping of the alternator V-belt; 2. Damage to the alternator bearings; 3. Rubbing between the rotor and stator; 4. Contact between the fan blades and the front end cover. The car alternator is the main power source of a vehicle, whose function is to supply power to all electrical equipment (except the starter) while the engine is running normally (above idle speed), and simultaneously charge the battery. Based on the three-phase stator winding of a conventional AC generator, the car alternator increases the number of winding turns and leads out connection terminals, adding a set of three-phase bridge rectifier. At low speeds, the output is from the original winding and the additional winding connected in series, while at higher speeds, only the original three-phase winding provides the output.
I'm quite qualified to speak on this matter, as I just helped a friend deal with a similar issue a couple of days ago. The most common cause of abnormal noises from a car alternator is belt problems. Worn-out or aged belts can produce squeaking sounds, especially noticeable during cold starts. Another frequent issue is bearing noise; when the alternator bearings lack lubrication or become damaged over time, they may emit continuous whirring or humming sounds. Additionally, loose mounting brackets can cause clunking or rattling noises, which require tightening the screws. Personally, I've also encountered cases where worn alternator brushes inside the unit caused clicking sounds. If you suddenly hear unusual noises while driving, it's advisable to immediately check if the alternator fan has trapped debris like leaves, as these pose safety hazards and could potentially burn out the alternator if not addressed promptly.
