I have a mystery belt squeal that I havent been able to hunt down on my 1999 5.2 Magnum.

It started when I washed the engine about a month ago. It started small and has got worse and worse. I seems to squeal once or twice an engine rotation at idle, and then fades out when cruising, mabye from being drowned out by exhaust noise.
In the last month, I have replaced the belt three times, replaced the idler pulley and bearing, and replaced the tensioner pulley. It currently had a napa belt on it.

I noticed when I replaced the belt and idler pulley most recently that the idle pulley was glazed/polished where the back of the belt was riding on it, and all of the tops of the grooves on all the pulleys were shiny.

All the bearings spin freely without issue, nothing is grindy or loose.

The most recent belt didnt squeak for 2 days of driving, maybe 30 miles. It slowly got worse. I thought I had fixed it.

Kind of at a loss. Any help from someone with more experience would be greatly appreciated.

 

Do you have a/c? Does it work? Does the squeal change if you have the a/c on? (it also comes on in defrost modes....)

 

Are all the pulleys in alignment?

 

Dupe Pls delete

 

How much deflection in the belt? Should be half inch of play. Maybe your tensioner is weak. Gas the truck by hand at the throttle and listen carefully. See if its actually coming from the belt. Spray water on the belt, does it stop?

 

How exactly did you wash it? If you used a car wash, some of them recycle the water but since it's not potable it may not be cleaned very well. Your pulleys may be contaminated with grease and what passes for wax at the car wash if this is the case. And, since it can be assumed that you washed it because it was dirty, grease or oil from your engine may have gummed up the works. You might try scrubbing the pulleys with engine cleaner and a tooth brush, getting all the grooves, and rinse with clean water. A misaligned pulley can be seen by sighting down the pulleys from the side, the one that's out will appear to be closer to or further from the engine than the others. The belt will also show wear signs on the sides if it's bad enough. You'll also want to clean the grooves on the belt, or replace the belt again.

Another possibility, an accessory bearing is about to give way and washing was just coincidental. Try spraying WD40 behind the alternator pulley, water pump pulley, and power steering pulley where the shaft and bearings are, preferably while the squealing is in progress. It'll just take a tiny shot, and if it's an accessory bearing causing the problem it should go silent immediately. Keep in mind this is a quick and temp fix to allow you to isolate what may be failing, not an actual solution. Whatever goes silent will still need replacing. It's also pretty dangerous as you'll be spraying while the engine is running. The fan or the belt can grab hold of you if you aren't paying attention so this is one of those "at your own risk" kinda things. If the squeal is pretty good, you can shut the engine for the actual spraying if you're not comfortable doing it on a running engine but just do one pulley at a time if you do. Otherwise you won't know which one actually cleared the problem.

Hope some of this helps.

 

When the belt sprayed is with water with the engine running, the squeak stops. Then returns in about a minute once it dries.
As far as I can tell visually, none of the pulleys seem to be obviously out of alignment. I guess that still doesn't mean they couldn't be...
I'm afraid if I do the WD-40 trick, it will fling everywhere and get into the pulleys.
I THINK the issue may have originated when I washed it:
I coated the underbody with some of that fluid film stuff months ago in preparation for another salty Wisconsin winter. I washed it with a hot water pressure pressure washer at work, some of the fluid film got sprayed up into the crank pulley area.
I'm thinking some might have gotten onto the belt and pulleys, making it slip and squeak.

I washed the belt and pulleys with soapy water and a tooth brush and dried it all off with compressed air. Belt started squealing again on my next commute. $%&#!

I was using my A/C this summer. It worked.
I bought a belt to bypass it for now, and the squeaking stopped.

 

WD40 won't actually damage the belt or pulleys. Does it squeak when the AC is on? If the compressor was the problem, it's possible the compressor clutch was contaminated when you cleaned it. It should be possible to replace the AC clutch, but you should get a second opinion before doing all that. I'm just a guy on the other side of a screen that's never seen your truck.

 

Ive had that when I use either a "cheap" (store private label brand) or a Dayco belt before. Especially when I had my Wrangler. and very soon after replacement. (that was a 4.0 inline 6 that came from the factory w/o AC) put a Gates on it and I had much less problems.
Anything misaligned?