Sorry to keep bugging everyone about this, but I just don't know.
77 dodge van 318. On startup ammeter needle swings from full charge to midrange. Loud squealing when ammeter needle swings to full charge. Noise goes away after engine warms up. I think I tried tightening the belt long time ago and made no difference. Visual inspection of belt appears ok. It is one of those kind that is serrated on the pulley side, but no glazing or obvious wear.Looking at a shop diagnostic report sheet from long ago it is somewhat illegible but says, under "Alternator Output: Bad Dode stator" which I guess legibly written means: Bad Diode Stator? Would this cause the noise? The belt looks ok and I brought the alternator down to Autozone for them to test on their machine. Test said it was ok, but Mgr. there said it was probably a bad diode in the alternator. Should I buy a new alternator and see if the noise disappears?