1999 3.0 185k miles

The squeaking comes from the fan belt area in the middle of the engine bay but it’s hard to tell for sure, so I suspect it’s the idler pulley. What is throwing me off is that the squeaking won’t happen until the engine is warmed up, so there is no squeaking on startup. There is a little play in the pulley but not a lot. The belt, power steering pump, and ac compressor are new. Any other ideas of what it could be?

 

Not sure anyone can answer this, lol

You can use a hose as the stethoscope and listen to each pulley after engine is warmed up
I use a smaller hose taped to a dowel(stick) at the end, so I can get it to where I want to listen

Common squeak on a 3.0l is from the top rear, the cam synchronizer bushing wears out and needs to be replaced every 80-100k miles

 

Update:
I replaced the idler pulley and tensioner assembly and that seemed to do the trick. The fan belt was loose to the point where I could slip it off with only my hands but now it is tight and doesn’t squeak anymore.