2006 f150 5.4 3v lariat
A few month's back I started getting a loud squeal while I am accelerating so I figured it was coming from my serpentine belt or pullys I changed out all pullys and the belt and put a new belt tensioner on and it still squeals, the squeal sounds like it's coming from the passenger side i do have an exhaust leak on the manifold any knowledge on this will help.

 

Pull the belt and try it. It will run for a few minutes without overheating, but the steering will be stiff. I bet it might have something to do with your other thread with the wobbling pulley.

 

I tried this and the truck sounds normal no squeal, it only squeals when I accelerate hard going uphill, not sure how to fix the wobbly pully its new and I've tried 2 different new pullys same wobble its like it needs an inner and outer washer to fully tighten but not sure if there is supposed to be an inner and outer washer on it not sure

 

You sure you have the correct pulley? Is it a genuine Ford part?

https://www.tascaparts.com/v-2006-fo...ts-and-pulleys

 

yea its a genuine ford part, i bought 2 of them thinking one was wrong but they do the same thing even the original one that was on there did the same thing so not sure

 

I did try one thing my truck had a cold air intake on it when I bought it came with the original intake so I switched it to original and the squeal quieted down alot, so maybe a vacuum leak causing squeal maybe not sure though

 

Is your radiator fan the old style and not electric? I had a similar issue on an old car I had when I replaced the failed fan with a "heavy duty" fan that acted like it was locked up all the time. When I accelerated the belt couldn't accelerate the fan quick enough so it slipped and squealed.

 

The fan is not electric haven't noticed anything with the fan it appears to work fine

 

Does the AC work well?

Idler pulley shouildn't be wobbling, should be steady with no drag too.

 

The ac works really good, the pully seems like it won't fully tighten down its like it need a washer to help it tighten down but not sure if that's the right way to go

 

Do you have a tuner on it by chance?

 

Some tuners are set at WOT. You said it happens when going up hill? After your trans kicks down? If you have a tuner, set it back to stock and see if that doesn't change anything. Just a thought...

 

Fan clutch? Just had this happen on an 03 SuperCrew 4.6. I thought it was u joints or a wheel bearing at first and changed those but it turned out to be the fan clutch.
I have also had a similar sound from a loose alternator pulley. It came off and I lost steering and brakes both at the same time... on an E-350 ambulance.

 

Gents, the problem is a wobbling idler pulley, please read the whole thread.