belt chirp/squeak

[rtreptow7]

2018 GMC 2500 hd 6.0 60K miles

Couple months ago, started getting intermittent chirp from belt/pulleys.  Seemed worse in wet weather. Tried trouble shooting. Sprayed water on the serpentine belt and it would stop the chirp temporarily. Figured a new belt would fix it. It did fix it for a few weeks, then it came back.  Sprayed water on the new belt again and it would temporarily stop the chirp again for a few seconds. I did a little more investigating and figured I would change the tensioner and idler pulley. Changed both of those and the stretch fit air conditioning belt (which was not fun) but that didn't stop it.  Tried another new belt, different brand this time, and the squeaking stopped again...for about only 3 weeks and now it's back. Spray a little water on the belt, and it momentarily stops the squeal. I can't determine exactly where it's coming from, if it's a pulley or what? If its a pulley, why does it stop when I spray a little water on the belt? I did remove the belt and just grabbed all the pulleys and spun them and they all seem to sound good and don't have any play in them.  Any ideas?

[Krusty]

When I replace a noisy belt, I like to spray off the pulleys with brake clean in case somebody has tried to cure the noise with some type of lubricant

[opnspaces]

If it was mine I would pull the belts and run some 600 grit paper through all the pulleys to knock down any glazing. Since it was squeaking I would also put a new belt on after the sanding.

[Latner]

Might be hard to see, but are all pulleys aligned?

[IB853347201]

Had a similar chirping happen on our Chevy Vortec 8.1. Cause was diagnosed as the idler pulley which was replaced, problem solved. 8 months later, started chirping again, squealing louder when it rained. This time it turned out that the alternator was the cause. Replaced and all is good now.