I havea 2003 Mitsubishi Galant es 2.4L. When starting the car, more often in cold weather, the alternator/belt will squeal. Then eventually after idling long enough, the noise will quit. If i start the car with the heat on or headlights, or any other accessory using electricity, the squealing is typically worse. The first thing i did was tighten the belts, which did not work. The next thing i did was replace all belts and idler pulley for air conditioner. In a short time the squealing was back. Then i replaced the alternator, with yet another alternator belt, which was a gates belt. Upon doing this, there was little or no belt noise but then the horrible sqeaking came back. So then i replaced the battery which had no effect at all. Then i replaced the alternator again, and the belt still squeals when you start the engine with any accessories on. I have tried everything i can think of and i have never had trouble fixing this problem before on any of the hundreds of cars i have worked on. Any help or advice would be appreciated.

 

probably a failing crankshaft pulley. Chances are its seperating.

either that, or you dont actually have the belt tight enough.

 

Did you solve the mystery squeal, and if you did...what caused it?
I have a similar problem and have tried almost everything

 

I have the same question as the guy befor me. I just bought a 2003 galant with the exact same problem. Ill start it, It sounds fine. I turn the air on and it squeels like a #$%^. Then ill turn the air back off and its fine again.

After its drivein for awhile and drivein lightly the sound stops.

Ive got 1 new belt and one old belt.

Timeing belt and serpintine.

Not sure which is which.

So in my opinion, i think its the belt that turns the ac compressor.

After i replace that ill repost and tell yall if it fixed it.

 

mine gets worse and worse every time on a cold start and it happens sometimes when you accelerate