Cookin alternators!

I have a 1988 Iroc Camaro that I purchased about 3 months ago with a small block 400 in it. I drove the car down from Michigan to Florida without incident. After about two weeks of driving around town the alternator gave up. Ok, no problem. I just went and bought another 105 amp alternator, put it in and a week later it fried. Both alternators melted the support ring of the battery output terminal! The only things I can see that would draw that much current without melting wires are the Battery & the Starter. Has anyone run into this problem befor? Any ideas where to start?

Side mount battery terminals?

Try replacing the battery cables.


Are we on the same page? I call it the alt. output terrminal- thickest wire coming off alt. comes from this terminal and goes to battery+ post right? I think we are. I’m assuming, under normal circumstances this “ring” is electricallly connected to terminal, and output wire. Either this wire is partially grounded before it gets to the battery pos. post or the wire/terminal/ring is grounded to body of alt. No offense, got wires properly hooked up to alt? How did you come to conclusion first alt was bad?

when you push a lot of current through a bad connection, you get a lot of heat. Check the lug that connects to the battery output terminal. It should be shiny and clean. Also inspect the connection between the lug and the wire. If any heat damage is evident, replace the cable.

I agree with markmast that there is a problem with the B+ output terminal at the alternator. After you have done everything markmast indicates, run the engine with as much electrical load as the alternator will see, i.e. long nonstart crank, lights, blower fan on high, AC on, etc. After a while carefully touch the output terminal/post to see how hot it is running. If it is still more than confortable warm, you have not solved the problem.

We are on the same page, but it’s labelled “BATT”. Anyway both alternator “BATT” post insulators (made of plastic) had melted, so the post was loose and was no longer showing an output! Thanks for asking though!

What do you mean, “Thanks for asking though!”? That sounds like sarcasm to me! None of us need sarcasm or “attitude”. We have to ask people questions about their problem. It’s not a one-way street in that regards. // I think you could save yourself another burned out alternator if you took the car to a mechanic to examine those connections you made.

My interpretation was that he was being friendly, hellokit. Nuipohaku- The more I think about it the more it seems markmast and Reasearher may have a better hunch. The only fly in the ointment to me is, why did the same symptoms occur on both alt’s? Don’t be afraid to try to elucidate more; to try to anticipate questions we may have and ask them. Please post back!

Since these cars never came with 400 small blocks this means someone swapped the engine out. My memory is real fuzzy on this issue, but what about this possibility.
Some Chevys of this era used a resistor in one of the wires going to the alternator and I think it was the wire that “sensed” the battery voltage. What if this resistor was no longer in place? Wonder if this could allow the alternator to basically go nuts on the charging?

I mention this because a motorcycle example of this happened to me some years ago on my alternator Harley shovelhead.
It kinda went like this. (The alt. stator is replaced separately from the permanent magnet rotor)
The voltage regulator went bad and I replaced it with an aftermarket regulator.
On a highway trip later on the alt. went out.
Changed the alt. and everything was fine for a while until another highway trip dropped the stator yet again.
Irritated, I went through that bike with a fine tooth comb and could find nothing wrong with it.
Replaced the stator for the 3rd time and in the future it dropped yet again. (10 o’clock at night and 65 miles from home. Thank goodness the moon was out.)

At this point all 3 bad stators looked good but none would work. So I dropped them all in the carburetor solvent and soaked all of the insulation loose. Unwound the field coils and here is what I discovered.
There is a single regulating winding on the stator frame followed by insulation followed by the main windings.
All 3 stators had roasted regulating coil windings with untouched field coils.

A examination of the regulator showed that this regulator, which has a tiny 4 pin female connector, was actually made where one of those 4 pins (the regulating winding pin of course) was a dead hole and this caused a disconnect between the alt. and battery.
Essentially what was happening here is that the alt. could not sense the battery voltage and eventually the reg. windings would fry due to the alt. output not being under control.

This is a bit lengthy and don’t even know if this is related to the OPs problem or not; just providing some food for thought. :slight_smile: