Thread: What is this

Looks like the tensioner for the acc. belt.

I'd remove the belts first and see if the sounds are gone. Then install one belt at a time to make sure you can pinpoint what belt/pulley it's coming from.

If you can tell its that one squeaking... I usually just take the belt loose and spin it by hand to confirm... thats a tensioner pulley on the alternator belt. You can get just the pulley (includes the bearing) fairly cheap at most local parts stores. Its a 5 minute fix and maybe a $10 part. Theres also an idler pulley, and I think just a tensioner on the S/C belt.

A little movement might be ok, the arm that pulley is on is spring loaded hence the term tensioner. It holds the belt tight unless its broken. Since your belt is still on, I'd say thats probably ok but your pulley may to lock up soon. When it tries to and squeals, it yanks against that tension spring and thats probably what you're seeing. That means the tensioner is good but hurry up replace the pulley now because you don't want a belt to come off.