Just had water pump, belt tensioner assembly, and serp belt replaced about 500 miles ago. Belt squeals like a banshee. No matter warm or cold, idle or 60 mph. Is it possible it's too tight/loose? I've tried dressing it, makes it worse. Thanks for any help folks!

 

The belt has stretched a little over time, just tighten it a little. Stop using belt dressing on it, that is not good to do on that kind of belt. That's why it made it worse. You use belt dressing for old v-groove belts. Just go get it tighten and all that belt dressing cleaned off.

 

The belt should have been re-tensioned after 10 minutes of running under load.

Apparently you didn't do that. As another poster said, you need to thoroughly clean all the dressing off the belt, pulleys, and grooves. Then re-tighten.

If it still squeals, you ruined the belt with the dressing. Get another, clean the pulleys, and start over.

 

Thanks for the answers Duma and Firestorm. Probably just get a new belt and start over. Thanks again

 

If this is a 4.0, you've got a bolt tensioner, right? It's very difficult to know how tight is tight enough. I had the same problem after replacing the water pump in my 97 ZJ. After tightening it more, I toasted my stationary idler. $6 at PnP fixed that.

 

Total 1" deflection at longest free span of belt has held me in good stead over the years.