loud squealing from under the hood

[waffletoast]

In my 2004 Ford Explorer, 4.0L v6, there is a loud squealing sound coming from around the alternator. I have replaced the idler pulley, alternator and the serpentine belt but the sound still hasn't changed. It still sounds like the noise is coming from near the alternator. The belt feels a little loose but the tensioner arm is fully extended. As the belt goes from the tensioner to the alternator, it seems to wobble. Any ideas of what could be causing this? Thank you in advance!

 

[ponkotsu]

Has to be a pump or a pulley. I'd suggest you get a mechanics stethoscope and see if you can pinpoint it. Be very careful around the pulleys with it though so you don't get your head torn off. That would make worse squealing noise. Kind of like the squealing noise a raccoon makes when the are sleeping on the engine when you start it in the morning.