OK,the alternator on my '95 945T is screaming. Squealing noise, seems to be from rear of unit. Replaced it twice-a used one and the known-good one from my '94 940T. Same thing. Noticed the out voltage is low (12.8 to 13.5V) when the screaming is happening. Sometimes,very erratically, the screaming stops, voltage goes up to normal. Swapped out the battery from my car-not the problem. Checked harmonic balancer with timing light-solid.THere is some short, I guess that is dragging it down. But no fuses are blowing,everything works,no wires getting hot. Back of alternator heats up when screaming.Please-suggestions?
Car has 195K,my 940T just turned 228K

Belt good and snug? Belt tensioning hardware (long 6mm bolt) in good shape?

The belt is not slipping ( I can tell because if I spray somehing like no-residue contact cleaner on it, the noise does not change at all). Noise is coming from the alternator rear itself. The alternator in there now (from my sedan) is getting so hot that the black plastic cap on the front of the pulley has melted off!

Is it aligned correctly? Belt straight? Rubber bushings not mashed down?
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See the 700/900 FAQ at the drop-down menu above right.

Yep, replaced the bushings.Another thing I forgot to mention is that the battery is staying charged,even though this short is almost devouring the whole output of the alternator. How to find a short that only occurs whan engine is running...hmmm.