I seem to have really bad luck with alternators. I have now ordered 3 one wire alternators. One never worked out of the box (and it was going to cost me just as much again to send back to the U.S). The next one worked until recently when it started to really whine and get really hot. I decided to order a brand new one which cost a small fortune as it came from the states.
It would charge the battery but would also get really hot and whine under load. I then tried to order a correct fan belt but when it turned up it was the same as I had already been using. You can hear the noise in the video below….
I had tried loosening and tightening the belt but nothing seemed to sort out the whine. The pulley of the alternator got seriously hot even after only 30 seconds so I was confident that the belt was slipping, which was causing the build up of heat. If the car was idling the squeal would reduce or stop all together but any gas would cause it to occur.
I have a volt meter gauge in the car so that I could see if it was charging the battery and even when I had the car at 2500 rpm (which is when the regulator should kick in) nothing seemed to change (towards the end of the video above)
I tried one more time to tighten the belt as tight as I could get it and amazingly the squeal seems to have gone. I then tested the alternator with my handly tool and it seemd to show that it was sending around 13 or so volts to the battery BUT the gauge in the car doesn’t match up so I have to look into that.
For now though, the noise seems to have been solved but the proof will be when I next get to drive the car…and the weather is not co-operating at present.
Update: Well, a lot of fiddling later the noise issue appears to be solved. I thought I had the belt tight enough with the expected level of deflection but I ended up using a pry bar to give extra leverage before tightening and all is well again.
My Mustang Journey 