I started hearing this loud whining sound which I think is coming from the belt when starting up the car in the morning. The sound dissipates after about 5-10minutes of driving. I have 39k miles on the car at the moment. Is it coming from the belt, is it loose, does it need to be replaced\readjusted? Thanks in advance.


https://www.dropbox.com/s/ye5gfsc2z22g1 ... 0.mp4?dl=0

Hard to tell from that, but the overrunning clutch on that alternator is pretty noisy. You may have a bad alternator and not a belt problem.

Would a bad alternator have a constant sound at all times or just show when first starting the car?

If it's the clutch then they often misbehave with temperature. Put a stethoscope on it, if it's the noise source then you'll hear it very clearly.

VStar650CL wrote: ↑

Sat May 08, 2021 7:35 am

Hard to tell from that, but the overrunning clutch on that alternator is pretty noisy. You may have a bad alternator and not a belt problem.

Could it be the idler tensioner bearing?

phmichel wrote: ↑

Sun May 09, 2021 8:12 pm

Could it be the idler tensioner bearing?

Sure. It definitely sounds metal-ish, so it could be anything turning with the belt.

Strangely enough the sound did not occur the last two days ( I am not complaining). I took it to the mechanic and they said belt looks new and there is no sound coming from it so there was nothing further they could do. I was watching this video and it helped explain on how to troubleshoot the sounds. Since there is no sound right now I did not spray any water to test. Also I will try to get a voltmeter to test the battery but didnt see the lights dimming while opening and closing the power windows with ac on.

https://www.youtube.com/watch?v=_8RE8p_m8bA

Rogue2015NYC wrote: ↑

Mon May 10, 2021 5:45 am

I was watching this video and it helped explain on how to troubleshoot the sounds. Since there is no sound right now I did not spray any water to test. Also I will try to get a voltmeter to test the battery but didnt see the lights dimming while opening and closing the power windows with ac on.
https://www.youtube.com/watch?v=_8RE8p_m8bA

I haven't used that particular product but he's right about emollients, the top of that belt was clearly glazed and softening the rubber is what's called for. For the most part, conventional "belt dressings" are crap. I wouldn't worry much about the alternator output unless you're getting an on-and-off generator light. Even if the overrunning clutch is making noise, they pretty much need to fail completely before you'll see charging issues. Like I said, if it isn't the belt, a stethoscope on the alternator body, water pump body, and the center bolt on the tensioner pulley will give you a good idea of where it's coming from. The AC compressor can be eliminated just by cycling it on and off, if the AC clutch is noisy then it will disappear with the AC on, if the compressor itself is noisy then it will disappear with the AC off.