Belt Slip? Squeel?

I have this weird squeal when I am at full boost and I can only assume its the belt. Its not really a high pitch squeal but its the best way I can describe it. I do have an MP spring on the SC tensioner and the tensioner clocked. But I am running an aluminum 5% SC pulley and 5% JS pulley. Would the aluminum be the culprit? It only does it under load. The aluminum idlers also have belt dust all over them after after only a few miles.

Thanks for the help.

It's possible it is the tensioner/idler pulley. Might be worth putting the wider plastic OEM idler pulley on. Before that though, make sure the clocked tensioner hasn't moved on you. Check range indicator once you are sure it is tight. I used a paint pen to mark the position of my tensioner to the bracket so I can detect rotation at a glance.

not sure what belt it is for the 5% od or the js od pulley, but i have the 10%od for the sc and the belt size is k080390. When you put on od pulleys you have to use smaller belts or you will get belt slip, its not much at all though, like for my 10% od i think it was only like 3/8 of an inch or something like that. check the advanced search for your pulleys you might find something there for exact belt sizes.

pablon2 said:

It's possible it is the tensioner/idler pulley. Might be worth putting the wider plastic OEM idler pulley on. Before that though, make sure the clocked tensioner hasn't moved on you. Check range indicator once you are sure it is tight. I used a paint pen to mark the position of my tensioner to the bracket so I can detect rotation at a glance.

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Well Its not a belt. I had to tach it up pretty high but it coming from where the bypass valve. If they were bad would they squeel? It doesnt seem to have a vacuum leak anywhere. but my gauge does 25 in/hg at idle.