O.K. forgive me if this particular thing has happened to someone after putting on the 2# upper pulley. I had no problems putting the pulley on, easy installation, used the same belt from the factory. Went for a spin and wow, what a difference. After the second hard accelaration, I noticed a noticed a knocking sound. First thought, getting ready to blow. Went back home, did a few throttle pushes from under the hood with a hose to look for the source of the knock(all the mean time getting paranoid about engine blowing up). Would you believe it was the supercharger belt? After determining it was not coming from within the engine, I grabbed the old belt dressing(hate the stuff) It would shut up the noise up for about 30 seconds. Grabbed the bar of ivory soap which would shut it up until a WOT run on the truck again. Began to smell burning rubber. Finally got a new belt from Ford, problem solved. It was a completely different part number than what was on the truck.

I have NEVER heard a belt make that kind of knocking noise. I have heard a lot of noisy belts, but never one like this.

 

sounds as if your pulley isn't aligned properly...

 

At first, I thought of that, but after I got to thinking about it. The belt had been making a knocking/chirping noise on a cold start up. By cold start up I mean the truck wasn't started for a week or maybe two a couple of times. Once the new belt was on, no problems. I looked over the belt and there were some funky rub marks in a couple of places.

Just thought I would share this with someone else before they freak out.

 

I think its the one of the other guide pulleys that is just below the blower pulley. Mine used to make that pinging noise all the time before I got rid of them. Almost like a piece of metal rattling around inside metal box kinda sound.

 

I thought it was that patch of labeling on the back of the belt making noise on one of the idler pulleys, but that wouldn't explain the placement of the soap to quieten everything down. I checked the alignment of the upper pulley again, but did not check the lower pulley. The factory belt was tremendously loose once the new upper pulley was on. Just a little un-nerving when you hear that kind of noise. I honestly thought it sounded like a rod or wrist pin was about to go. It would only make the noise as the RPM's were returning to idle. It was like slack noise if that makes any sense.