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Ryan from Ohio wrote:I doubt its bearings in a new alt.
Chancers are your idler pulley needs to simply be replaced.
Also try some "belt dressing" spray.
IMO< do it yourself and save your cash.
Take the belt off, spin each pulley. If it doesnt spin ultra smooth, theres a problem. If there is any sort of tick, hold up, bind, grind, etc its a bad bearing.
Replace it now before you run into bigger problems later.

Yeah, what he said.

I doubt its bearings in a new alt.

Chancers are your idler pulley needs to simply be replaced.

Also try some "belt dressing" spray.

IMO< do it yourself and save your cash.

Take the belt off, spin each pulley. If it doesnt spin ultra smooth, theres a problem. If there is any sort of tick, hold up, bind, grind, etc its a bad bearing.

Replace it now before you run into bigger problems later.

What kind of squeel is it? When the bearing in the alt is going, you get this sound that sounds like a really loud flute or something.

What kind of car?

Some cars have adjustment at the idler (to compensate for slight differences in belt length, but also works with slight differences in pulley diameter).

Some cars (Ford comes to mind) have zero adjustment, and when the bearings in the idler start to wear out they make noise.

It could be that your new HO alternator has a different diameter pulley than the one you replaced. If so, it may be possible to put your old pulley on your new alternator.

Cheap mechanic's stethascope: get a piece of vacuum tubing approx. 3' long. Stick one end in your ear, and hold the other end up to all suspected sources of the squeal with engine running, being careful not to sacrifice hands to moving parts.

This could be bad news- I had a Blue Oval product with two seperate but simultaneous squeals I found this way...the belt tensioner (idler) pulley and the bushing at the base of the distributor were both fried. The distributor was easy, but to replace the tensioner I had to undo all motor mounts and jack engine/trans up 4" just to get a wrench on that sucker due to it's placement in the engine compartment.

what you have is the new belt has a logo painted, numbers and brand of it . the motor will wear it off. old school get a wood broom handle and run the motor put the handle on all the parts,brackets that the belt is moving and put your ear on the other end of the handle and listen for the sound(be careful not to hit moving pulleys or fan blade) or get a mech stethoscope to find the noise.

Hey there, a couple months ago I had upgraded my alternator to h.o. one from knukoncepts. Imediatelly after it went in the idler pulley started squeeling. I had the mechanic who put the alternator in take a look at it, but he never did manage to figure out the problem(kinda incompetended). So after I got back into town from being away at work for a while I brought it to another mechanic. He put a new belt on(even though there was 0 wear and tear on the old one) and grinded some paint on the idler pulley. While it was in his shop, and for the remainder of that day, not a sound, and I thought everything was great. The next day however, we're back to the same old squeeling sound. The squeeling also sounds like its coming from another pulley now, not a hundred percent sure on this. I now have put in over 350 bucks to two diffrent mechanics for a problem that is still there, obviously neither of those guys know what the problem is. I was wondering if anyone here faced a similar problem???