I've been hearing a grinding noise coming from my engine recently so I took a look to see what was making it. The grinding would occur when I start the car, shift gears, and let go of the throttle. I noticed that it was coming from the serpentine belt side so I looked there and I noticed there were metal shavings on and around the alternator so I was expecting it to be my alternator failing. I took the serpentine belt off and after spinning each pulley, the alternator pulley had a bit of a wobble to it and I heard a tiny scratching sound as I spun it. I also noticed that it would freely spin in both directions which I heard is not supposed to happen on an OAD alternator. So, is it the alternator pulley that failed, the alternator itself (I don't think it's the alternator since it works fine and my car doesn't have trouble starting), or is it something else? Any help is appreciated.
Grinding Noise from Engine Bay
- Thread starter ZeCorolla
- Start date
It turned out to be the alternator pulley bearing. I've taken it apart and the pulley goes in both directions (not supposed to happen on these design pulleys, they are supposed to only spin in one way), it has play when I wiggle it, and I can hear slight scratching as I turn the pulley by hand. Now, I'm deciding on whether I should just replace the pulley or the whole alternator.
I think I've narrowed the grinding down to either the bearing or the decoupler pulley. I had a mechanic look at it and he said the belt's a bit loose so I should tighten it and see if the sound goes away otherwise it's the alternator that failed but if it is the alternator, I would assume that my alternator would stop charging my car if it failed. It's working perfectly fine so I think my alternator is fine. If it's the decoupler pulley, then the metal shavings are from the pulley scratching the alternator housing.
As I originally suspected, it was the bearing that failed. I could have rebuilt the alternator myself but that means not using my car for 2-3 days which isn't possible for me so I just bought a cheap rebuilt one and swapped it in. I'll rebuild my old one sooner or later and sell it or keep it as a spare.