Squealing Sound Not Belt

Got a 2004 3.4L V6 4x4. When I start the car and put it in drive I hear a squealing noise from somewhere the driver side. Almost sounds like a hose or something is leaking air. It’s not a belt I checked those (kind of sounds like it though). Has anyone ever dealt with anything like this? Or have any good tools to find where the sound is coming from? I tried a stethoscope but can’t pinpoint the sound. Only happens in drive and goes away after 15 minutes.

Thanks!

 

I had this issue and it drove me nuts, so much I put a new alternator in it and it persisted. I thought I had the alternator belt tight enough, followed spec by deflection, guess I didn't. If it's not just right the alternator bearing will complain.

It would do this on startup, sometimes for 1-2 seconds.
Sometimes I'd start it up, fine, start to drive, it would complain, then go away.

Check it again, and try tightening it a little at a time. There are two lock bolts, the big one on top and one underneath that locks the adjusting bolt. Make sure you loosen these a tad before adjusting.

 

I don’t think it’s the alternator I put my stethoscope right on the alternator while the noise was there and it was quiet. That was my first intuition too but doesn’t seem to be it

 

Tun the other pullies when you take the belt off. Fact it happened after the belt would lead to believe it has to do with that. Ive installed and alternator without testing it first and turns out I got a bad one.

 

also be sure you check the idler pully's. my other vehicle, all 3 of it's idler's smoked the bearing around the same time, but sounded almost exactly like a belt noise.