I posted this once before, but not really good answers.
Old dodge van mid 70's, 318. Alternator had spacer that one bolt slipped in.
Long time ago I lost the spacer and used washers to align the pulleys with the bolt alone.
Worked for a long time.
Now: LOUD squealing on startup, when engine warms up, squealing goes away. Squealing ONLY occurs simultaneously with alternator gauge needle bottoming out in charge position, alternating with normal position, in which case squeal disappears-i.e. as long as needle swings back to midrange position squeal disappears, only to reappear when bottoming to charge position. Squeal and bottoming of needle go away completely when motor warms up.
Checking the belt it is one of these kind that has teeth on inside pulley side surface. Belt looks ok-not worn; appears undamaged, but is somewhat loose about 3/4 to one inch deflection.
pulleys SEEM to be aligned correctly eyeball check only.
How do I differentiate between a squealing alternator versus a squealing loose belt vs a squealing out of alignment pulleys? What is causing the alternator gauge needle to bottom itermittently to full charge, swinging back an forth between that and midline reading-is this a function of a bad voltage regulator?
I cannot run this thing too long as my neighbors will complain about the noise.
I wish to avoid replacing a $100 alternator if that is not the cause.
How do I differentially diagnose the cause of the problem. Anyone? Thanks.