So when I bought my truck it had a sqeueeky belt. I put on new idler and tensioner pulleys and a new belt, didn't help. Today I replaced the tensioner itself, still squeeking. Not even a tiny bit different. What the hell could be causing this? The fan clutch seems to have resistance spinning it by hand, and it makes no noise by hand. You can hear it come on then kick off when running.
What else is there? Ideas, thoughts. suggestions? I'm open to anything. Its just so annoying!

(PS Not the truck in my signature, its a 93 3.9/5 speed/4wd)

 

Does it squeal all the time? Cold? Hot?
Try belt dressing spray? Maybe a worn pulley?
Sure its belt / pulley related?
Try short run no belt?

 

advise against using belt dressing on a serpentine belt. according to google you have a serpentine belt, i might be wrong.

 

its possible the fan clutch is on its way, I know mine was leaking the wax crap that's in it so I had to remove it... it never disengaged... no power louder then the tires i got LOL, if got the tool to remove to try its worth a shot.. otherwise it might be another pulley with resistance causing slipping or such on the belt...

 

Mine had the same problem. A new crank pulley solved it.

 

Spray the alt pulley and ac pulley as well as the ps pulley with pb blaster. Make sure not to get any in the alternator. Most of the time, in my experience, it's been the ac pulley or the alt but it won't hurt

 

It squeaks all the time. I don't wanna do belt dressing, in the past that has always backfired for me. Its definitely one of the accessories, doesn't do it with no belt. I'll try a little pb. I'm thinking its not the fan clutch only because you hear it on when you start it and disengage after a few seconds.
Just curious, how did the crank pulley cause a squeaky belt?

 

squirt WD 40 on the belt, if the noise stops then is a belt issue.

 

I'm not really sure. I just remember that the squeak went away when I replaced it (after first replacing pretty much everything else driven by the belt, with no improvement). I think it might have been worn so that the belt ribs bottomed out in the grooves (or the ribs on the pulley bottomed out in the belt grooves).

Didn't really make sense to me, either. That's why I replaced everything else first.

 

The front crank pulley is a harmonic balancer. The outside of the balancer is held to the inside of the balancer with rubber. Over time that rubber dries out and the outside shifts from the inside. It could be off by 1/32" and you can't see it but it throws the alignment of the belt off and rides on the edge of the belt causing it to squeak. I second Tom A and say it's the harmonic balancer.