My serpentine squeals/chirps at the water pump. I've changed: idler pulley, belt, water pump & water pump pulley. Nothing eases or stops the sound. HELP!?!?

 

It's probably too loose. The best way to check it is with a proper deflection tool, but I've had success with the "once you can't turn the belt more than 90 degrees" (as measured at about the middle on the section between the PS pulley and the idler).

 

Loose belt. The tendency is to under-tension the adjuster for fear of going too tight.

 

Too loose x3

 

Used the 90° method to tighten it...plenty tight...still squeals.

 

My '96 XJ I used to own was fine with the "yeah that looks about right" method. My '00 is not. When I redid my alt I used the 90 degree method. Then I checked it with a Krikit II. It was barely at 100 lbs and minimum for a used belt is supposed to be 140.

 

My advice - Get a new Continental Elite belt (formerly Goodyear Gatorback), it's the same price as a standard belt and is available on Amazon as well as at many other retailers. Get a belt deflection tool while you're at it.
When you take the old belt off, spin each of the pulleys by hand and ensure they are smooth and quiet. Use some brake cleaner to make sure all the contact surfaces are clean and oil-free.

I went through all kinds of hell trying to eliminate squealing on my previous Jeep (a TJ with a spring loaded auto tensioner) and as soon as I put the Gatorback style belt on it, I never had a problem again.

I'll bet that the slipping on the current belt has caused it to glaze the flat side up enough that even at proper tension it's still slipping just enough to make noise.

 

My only question is...how can it be glazed while brand new? It's currently only been on there for 3 weeks, but it started chirping the first day.

 

What kind of belt? For instance Napa sells two types. The cheap one, bought it for my '96 when I had it, that costs like $10. It was fine. Did what it was supposed to do. The better belt they sell runs like $30. Is a rebranded Gates. Seeing how my '00 is very finicky when it comes to belt tension was not going to cheap out.

 

Well, if the belt is loose, and you run it it will slip. The slipping will rub the flat surface of the belt and glaze it up pretty quickly and then the super smooth surface has a harder time gripping the smooth pulley. It's only one possible theory, of course. You'd have to look at your belt and determine if that's what is happening.

Honestly, I think a new Continental Elite Gatorback style belt, set to spec tension will solve your problem and you'll never have to worry about it again.

 

Most likely the pulleys are glazed from running the belt too loose.
I've fixed several cars/trucks in the past that have done this by bead blasting the pulley surface where the belt rides to allow the belt to grip properly.