I have a 96 blazer 4x4 and it constantly squeaks and I can't figure it, I've changed the belt, idler pulley, and tensioner pulley three times (all dayco belts) and it still does it, I'm guessing it's one of the pulleys has anyone had this before? any help is appreciated. Thank you

 

Keep in mind you still have AC, alt and power steering pulleys. Used to be nice back in the day before serpentine belts as each component had their own belt. You could remove each belt until the squeak stopped.

Try using a mechanic's stethoscope if you have one or a screw driver to your ear if you don't. Being careful, put the tip on each component and you just might find your squeak.