On the F450 in my signature, over the past few weeks or so I have noticed when I am driving and the rpm's get around 2500 i get a squeal under the the hood. I thought for a bit I had it traced down to the AC compressor clutch. As it was squealing when the ac was of or the clutch disengaged. It would squeal for a few seconds and then quiet down. It seems to be getting worse (go figure it doesn't fix its self) I figure if i wait long enough it will make itself well known. As a matter of reference I replaced the tensioner and belt about a little over a month ago, both from Napa.

Has anyone experienced this?

I was thinking that maybe it was part of the AC clutch assembly, does the clutch engage from the inside out and it is dragging or does it clamp front to back? I have heard that there are shims in the Clutch Air gap, could it be moving from centrifugal force and causing this noise? My Ac works good and cycles off and on like it should. (I know the difference between this noise and the fan clutch cycling.)

It does this when I get over 2500 rpms, I hear it when I start out just before it shifts to second, and then when I get on the freeway and am up to speed. (2500 rpm's is right around 65mph.)

I thought it was a boot leaking boost and making the noise, but all of them are in place and tight.

 

Seems to me, and my memory is lacking these days, but there may have been a pulley change on the 7.3's somewhere along your year. You may have the wrong belt. I hope someone else will jump in here for you.



Look at page 4 on this link. I know that you should have the smaller pulley, but maybe the parts guy gave you the longer belt

https://www.powerstrokediesel.com/do...ble%20Book.pdf

 

It may be the NAPA belt. I've had squeeling issues with brand new NAPA belts that I couldnt track down. Two belts in a row mind you. After it annoyed me long enough I bought a high dollar Gates belt from a different part house and it fixed the squeel.
I remember posting the issue, and quite a few other guys had similar issues with NAPA belts.
I tried belt dressing which made it worse, I replaced the tensioner, and all of the pulleys twice thinking I got a bad one, but It was that darn NAPA belt...

 

A high dollar Gates belt? I thought the one I got from Napa was expensive... how much are we talking here? I replaced both the tensioner and belt for around 110 if i remember right, and that was using my mechanics account to get a discount.

 

I honestly can't remember the exact price, but think the good Gates belt was around $80. Bought at O' Rileys
I couldn't tell you the price or make of the cheaper one.( I never asked) After wasting money on two NAPA belts I wanted their best belt.
I believe the NAPA belts are also Gates, but a cheaper cut of meat if you know what I mean.
My first NAPA belt shreaded after a few months of service. I bought the second one becasue a NAPA was the only store I could find. (I was stuck on the side of the road in "no where" Georgia.) It also took my hood insulation with it when It let go.

 

they had 3 different grades of belts, the one I got was the middle one, not the cheap one. go figure.

 

Donn, I'm running a Gatorback (thinks thats what its called) from Autozone. No issues.