New and tight alternator belt squeels

[rcx106]

As the title says the belt is brand new and tight but still squeels sometimes for a few seconds when I first start the car. Could I have damaged the pulleys by running a slipping belt before for too long? The alternator belt pulley looks discoloured from overheating :/

Maybe the pulley contact faces need roughing up somehow?

[S0 What]

If you told us what car it was we might have a chance at diagnosing the noise ??????
BUT i'll have a stab in the dark, does the alternator have a clutched pully? if it does that may be seizing, usually they wobble about if the bearing goes but if they seize they tend not to wobble, however if they turn but the clutch is stuck they cab cause slack and backlash on the belt that "may" cause a sqeel as it loosens off but usually that is at high revs and when slowing the engine ?

[rcx106]

Hi. It's a Vitara. No clutch on the alternator pulley. The alternator belt is driven by the crankshaft pulley (very large) and also drives the water pump. It's a four groove belt.

[Snake the Sniper]

When you say tight, just how tight do you mean? How much slack is there on the longest run?

[Mikey G]

Could be the crank pulley if it has a vibration damper pulley. The rubber in the pulley degrades and becomes loose and so the outer slips around the inner part causing the same squealing sound.

[Sardonicus]

I bet the belt is not tensioned enough people often fail to tension serp belts correctly often using the old V belt config as a reference ......... Wrong tension the belt so that on the longest run you can just get a 90 degree twist with firm thumb & fore finger pressure its generally accurate enough and you get a feel over the years for the correct tension on serp belts whether they are 3 or 8 ribbed IMO.