Belt question

[reborn55]

Threw the alternator belt off the wifes coupe last week.  Put all new belts on next day.  Went to a cruise last night and heard what I thought was wind noise.  Actually coming from under the hood at rpm's above 2500.  Got home and it was squealing chirping from under the hood.  Pulled alt. belt and noise went away--figure bearing going bad---pulled old alternator back on--same noise.  sprayed belt and noise got louder.  Changed belt to another spare and same noise.  Put the Dayco belt on that was on the car when I bought it and noise is totally gone at any speed or rpm's.  Don't know why it threw belt--had driven it almost 400 miles on the new belts.  Any ideas--everything lines up great.  thanks

[enjenjo]

Worn pulleys, something rubbing the belt, wrong belt width?

[reborn55]

Then why was the noise there with the exact same belt before it broke.  Other belt was new and the same number as the one I replaced.  Going to try to find another Dayco belt and try it.

[Mikej]

I had the same problem. Found belts that were actual US width. No more problems.

[rumrumm]

I had a squealing belt problem in my Safari van. Nothing seemed to help. I replaced the belt, Gates warranteed it and gave me another new belt, replaced the tensioner. It still squealed. Then a mechanic told me to put on a gatorback belt. After I did that, it has been totally quiet.

[Mikej]

I used the same style as Lynn. I think the problem was that the Gates, NAPA, Carquestbelts were running on the bottom of the pulley instead of the sides. You can't thighten them enough. I have several sets if anyone needs them

[jaybee]

Good point about belts.  If it's a fraction narrow it won't get proper side contact and no matter what it'll slip.

[reborn55]

Gatorback--found at local auto supply.  I deal primaruly with NAPA and they don't carry them