Serpentine Tensioner

I have diagnosed my bit of a squeal and sucking noise to the tensioner. Watching it when the engine is idling, it vibrates...like it's bouncing back and forth. Is that normal for it to do that? Or no? I think maybe that has something to do with my idle fluctuation when it happens!

Check your alternator pulley. It should freewheel in one direction and lock up in the other.

yep, did that. I put the screwdriver in and it turns one way and not the other. or should it only turn one way even without a screwdriver?

No, you did it right. Sounds like your tensioner is shot.

Ok, good. Alternators are sooo expensive!! So I should replace the whole tensioner and not just the little wheel?

Yes the whole tensioner. Also the alternator pulley can be replaced if it becomes necessary, no need for a whole new alt.

Ok, is that a pricey part? and yes, I heard...that's good to know, those alternators aren't cheap!