I have a very annoying and persistent belt squeak on an '86 GLH Turbo. It is coming from the alt/water pump belt. The car has been fitted with a rebuilt 90 amp Nippondenso alternator, smooth water pump pulley, and new bracket bushings from PolyBushings.com. (common block water pump/alternator/belt setup).
I was able to make the squeak go away for about a week after installing a new belt, but now it has come back. The belt doesn't screech like it is too loose, but makes a constant chirp-chirp-chirp noise that I can't seem to do anything about. I adjusted the metal sleeve in the alternator pivot point to get all the pullies to line up perfectly. I've tried adjusting the tension more/less without success.
I brought the alternator in to NAPA today and had it bench tested. It passed but it was putting out about 15.4 volts which they say is rather high. About the only idea I have right now is to remove the water pump pulley and sand it with some emery cloth to clean off any belt glaze and install a FWDP ground wire kit.
Anybody have any other ideas?