Alternator issue

[georgeramos]

This relates to my earlier post about belt squeal. When I drive with the lights on the belt squeals, lights off, no squeal.

I added a new ground wire from the negative to the bolt that cinches the alternator belt. no change.

What is the proper diagnostic procedure for this type of issue?

Thanks

[AndyVAS]

So the belt squeals under load... Simple enough, tighten or loosen or replace the belt. That failing to stop the noise, check the pulleys for wear.

[georgeramos]

Do the crank pulleys wear to the point of causing an issue? I am feeling like the NEW 95amp alternator is squealing as well at this point. I swapped the +battery cable, added a ground from battery to alt bracket, new water pump, new belt, frankly i feel stumped.

[kilrwail]

I had a squealing belt and the tension seemed right. In an attempt to isolate the problem, I put a tiny amount of white grease on the belt while it was running and the squeal went away. But it came back after the grease wore out. I replaced the 23 year old belt with a new one and the problem was solved.

[georgeramos]

I've tried 3 belts, 2 (95 amp) alternators, a new water pump, aligning and re aligning, a new battery cable clamp and a new ground strap.

My car has an "unrelated" issue in that the clutch release is at the very top of the pedal. So I think the RPM's ramp up BEFORE the car starts moving in most cases. Could that cause the alternator to 'not keep up?"

[spider2081]

IS it possible you have something putting a higher than normal demand on the alternator??? The original pulley size and shape was designed to work with original lower output alternators. If you have added something to the car that draws a lot more current the belt is working harder and (guessing) might slip. Many modern alternators use wider and or toothed belts to limit slipping. Theoretically an alternator puts out what the car asks for. if the maximum draw for a Spider is 45 amps @14 volts, that is what the supplies regardless of what the capacity of the alternator is. Many people have installed higher output alternators without belt slipping issues. If you are confident you have the mechanics of the alternator correct, belt tight and aligned etc. I would question if the alternator is being asked for a greater output than others who have installed them.

[baltobernie]

I've tried 3 belts, 2 (95 amp) alternators, a new water pump, aligning and re aligning, a new battery cable clamp and a new ground strap.

As Andy says, if everything else has been replaced and aligned, it may be a pulley. If the new alternators came with their own pulley, is it possible that their groove geometry is incompatible with the Fiat? Does the belt seem to ride in all pulleys at the same depth?

[georgeramos]

Great observarions and questions. I am going to take it to an electrical shop to see if they can find an errant issue causing too much draw. I havent added anything. Deleted the modern radio actually...