Okay, been trying to figure out whether the belt is slipping and making a noise or the alternator is going bad. This is a 130 amp alternator. With the car running, the alternator will squeel so god damn loud. With the power cables unhooked from the alt., I run the car and nothing makes a sound, it is silent. Hook the cables back up to it, and bam nasty squeal. Once the alternator has power, does the pulley get harder to turn as it puts out more and more power? It only gets louder as the rpm's go up. Could the alt. be seizing up when it starts to make the power, causing the belt to slip? We tried putting a pipe wrench on the tensioner with the car running, pulling as hard as you can, makes the noise go away at idle. But when you rev it with the wrench on there, it comes back. So i am kind of thinking it is the alt. itself and not the belt slipping.