New guy thanks in a advance. I recently changed my alternator to a 250 amp. Witch has a smaller pulley. So I changed the belt to a 1" smaller witch was recommended by that company. At the same time I change the tensioner. Have about 330,000 miles still strong. About a week later I started getting a squealing noise that is coming from that area. I used a mic and sounded like the idler pulley. So I changed both. Noise was gone for about two days then came back. I pulled all new stuff off and put back on old. Again went away for a couple days then came back. One thing I noticed when I took off the belt and spun the a/c pulley it rubbed a little I wd 40 it and it got better. It only squeals on acceleration and for usually about 30 mins of run time sometimes longer also when ever I take of the belt and put it back on it goes away for a day or so. Tonight i tried turning on and off the a/c while I was revving the motor at the loudest squealing point it did go away almost completely when it was on. Also I get a loud quick squeal when I shut her down. Is this a sign of the a/c going out. Its hard to mic exactly where it is coming cause the motor is so loud but I know for sure it is that area. If it is the a/c pump could a tighter belt cause this or just a coincidence. Thanks again!

 

Wondering if your batteries are running down and alternator is really working hard to get back to full charge? It's worth getting tested, I had a brand new battery internally shorted a little, drove me nuts till I figured it out.

 

Yes I fully charged both batteries separately and did load test before running new alternator one was like new the other tested good but was getting close to weak. Thanks for the reply.

 

If the squealing goes away when the AC is on then it is most likely the AC clutch going out, it will lock up and it will stall the motor or even trash the belt when it does. best thing to do is loosen the belt and spin the ac pulley by hand to see if it is smooth

 

I think I had multiple problems. One the alternator. It fried a couple days later. How can I get two bad alternators my luck. Second now the a/c clutch. Thanks for your help!

 

Ok, did you put a new belt on when you changed all of the parts? I put a goodyear gatorback on my truck and totally did away with all squeaks. Are you totally sure the belt is the right one? The alt pulley is the right one?

Did you upgrade the wiring to the new alternator? The ford wiring has an unspoken limit of 160amp. 250amp would be way beyond what the oem harness could handle. I put a 240amp on my X and ran a 0-gauge wiring from the alt to the pass battery, then from the pass batter to the drivers battery. Remembering that you also need to fuse that connection from the alt to the pass battery. I have a 300amp fuse on mine. Many will also run the same size wiring from the alt frame one engine to the truck frame and then from the truck frame to the body.... You need to also connect the oem harness to the alt. If you do not then the trucks computer will not know when to turn on the alt. Good luck.

 

Thanks for that alt info they just told me to change the wire from alt to the first battery. What you said makes sense. Thats what I thought should have been done. I just got my new alt in the mail today. So this weekend I'll give it another shot. And change the rest of the wires at the same time. Thanks again. O ya I went back and changed out the stock alternator at pep boys and put back on stock belt and all noises have stopped. I believe the 200 amp alternator was bad. My new one is from a different company. Plus twice as expensive. Being to cheap end up costing me alot more.