I own a 2007 Honda Civic. For the last several months, the car starts making a strange mechanical whining sound when turned on. The sound grows louder when accelerating or going in higher rpms. It also seems to get a little quieter when I turn on the air conditioning. But the soubd never goes away. Car otherwise runs perfectly fine and never fails to start. Took it to two different honda dealerships to have it looked at. One said it had something to do with the a/c, the other said the alternator might be the alternator. I tested the alternator with a voltmeter and it seems to be working just fine. However, when you open the hood, the sound seems to be coming from the alternator area. Please help, I don’t know what’s wrong with my car.
If it’s a chirping noise, it’s the belt
If it’s a whining noise, it’s a bearing (alternator, idler, water pump, power steering, etc.)
Does the car have an automatic belt tensioner?
Somebody’s Got To Get In There And Find The Source Of The Noise. You Can Be That Somebody If You’ll Feel Comfortable Working In The Danger Zone Of A Running Engine.
One could/should momentarily remove the serpentine belt and/or other “accessory” engine belts, run the engine, and verify that the noise stops, making sure it isn’t a transmission, timing belt system problem, etcetera.
Then one (with no loose clothing, hair, etcetera) could very carefully use an automotive stethoscope (available for 10 bucks at an auto parts store) to probe stationary parts (alternator housings, stationary nuts in idler pulley centers, etcetera) by touching the probe end of the instrument to various suspect parts (things run by belt) until the loud (whining, grinding, grumbling) piece is located.
Some noises can be detected by holding a length of hose to an ear and probing near moving items with the other end.
BE CAREFUL. Some parts are hot and will burn you. Other parts are moving and will grab you or other things. Keep hands, arms, legs, head, etcetera, well clear ! Pay attention.
A bad bearing will continue to get worse until a part locks up or comes off and will cause more trouble. The culprit needs to be located and corrected. Based on your description, the culprit shouldn’t be that difficult to find. I’ve used this method to locate even very subtle noises.
If you don’t feel comfortable doing this then don’t. Maybe a friend with a little know how could assist.
CSA
Thanks for all the advice. It definitely does not sound like a belt. I’m posting a short video with the sound to see if that helps further. The sound has gradually grown louder over the last several months.
It’s near impossible for me to determine noises from posted sound clips. It’s me; not you. My hearing is not that great.
A whine usually means a bearing and testing an alternator for voltage output won’t mean much because an alternator with bad bearings can charge perfectly fine.
You might consider removing the serpentine belt, placing a fingertip on the belt tensioner, near as possible to the alternator pulley, etc. and spin them by hand.
Often a bearing going bad can be felt in the tip of the finger. It may come across as a subtle tick type of feeling or a grating type of feeling in the worst cases.
The sound is similar to the sound I had in my 1978 Oldsmobile when the bearing on the air conditioner clutch was about to fail. When it did fail, the pulley on the air conditioner seized up and the belt started smoking and screeching. When you turn on the air conditioner, the clutch engages the compressor which might then give a different sound because there is more load on the bearing.
Its the Alternator Tensioner bolt and pully Replace it
With all due respect to SONU, I don’t think you should jump to conclusions and replace anything without more testing. But it does sound like a bad bearing in something driven by the engine, and could indeed be the alternator. Also check your power steering fluid level. When they’re low and sucking air, they can make funky whine that sounds like something else on some cars.
You might try taking the belt off and turning everything that it drives by hand (with the engine off obviously), and feel for any binding or grating in any of the accessories.