Whirring engine noise? Belt?

[Jand3rson]

When my alternator died last week, after we swapped the spare one I had in, my engine started making a kind of loud whirring sound, almost a whistling. I'm thinking maybe it's the alternator belt, being too tight, but I'm not sure. If a belt is too tight, does it make a sound like that? If so, what is proper tension on the belt? I checked the others just by kind of a quick tug, and they felt about the same. If it's not a belt, what could it be?

[PeaveyBassist]

Could also be the "new" alternator itself. i.e. bearings/bushings in it.

Will

[Jand3rson]

Could also be the "new" alternator itself. i.e. bearings/bushings in it.

Will

Mmmmm, I don't think so. The one we put in when we first replaced it was a 120k one from a parts car, then I went ahead and bought a new unit. The sound was there with the spare, and remains with the new unit.

[Alecs MacDonald]

Maybe try squirting some belt dressing on the pullys and see if the noise changes?

[Jand3rson]

Maybe try squirting some belt dressing on the pullys and see if the noise changes?

I'm not familiar with that, is it the same as like, interior protectant dressing?

[egk2]

Check the fan clutch, when mine went it made the same sound.
Btw belt dressing brushes on and quiets the belt from squeaking but it's
only temporary.

[Jand3rson]

Check the fan clutch, when mine went it made the same sound.

I thought about that, but it starter right after we swapped alternators, that's what makes me think it's the alt belt.

[Lobstrosity]

Might just be coincidental timing that it started at the same time...

I would check the fan clutch, just remove the fan to see if that makes the sound go away.

I had a similar noise when my timing belt tensioner started to die... so if nothing else seems to make it go away, check on that too. :(

[Alecs MacDonald]

I'm not familiar with that, is it the same as like, interior protectant dressing?

It is basicly just a can of wd40, anything greasy will work though. I have even used tire shine in the past when trying to figure which belt was squeeking.

[Jand3rson]

Might just be coincidental timing that it started at the same time...

I would check the fan clutch, just remove the fan to see if that makes the sound go away.

I had a similar noise when my timing belt tensioner started to die... so if nothing else seems to make it go away, check on that too. :(

Well, I have noticed since it got really hot that my fan is really loud, seems like it's louder than it should be. Can anyone confirm that an M20 fan is pretty loud, or should I really be able to hear it as much as I am? When it's hot outside, at slow speeds in 1st & 2nd, it's pretty loud. But the belt whirring I was talking aboiut in the first place doesn't sound like that, like I said, it's almost a whisting, pretty high pitched.

[egk2]

Fan shouldn't be that loud. Mine sounded like a jet when the fan clutch went.
Couldn't hurt to check it and rule it out.

[Jand3rson]

I've been itching to switch to an electric fan, maybe this is the time to do it.

I've already removed the belt from my non-working A/C compressor, of which I'm removing the whole system soon. Losing the engine fan/fan clutch to free up a little more power would seem to be the next logcial step in that direction.