New alternator smoking when battery connected. Need Help

[85supreme]

I've been chasing around a charging issue for the past two weeks on my 87 GN. I would have to charge the battery up in order to get it started and then once it started the scan master showed the volts continuously decreasing until it showed 9 volts and started idling like crap so I would shut it off. Revving the engine did nothing to increase the volts so I assumed the alternator had gone bad.

Replaced the alt with a reman from auto zone and had the same issue. Tested the alt when running and it was only putting out 12volts which obviously wouldn't do too well to charge the battery.

Then I noticed the volt light in my dash is out and read on here about how that will prevent the system from charging anything. Bought the field fix from casper's but didn't help anything.

So I took the alt back to auto zone and got them to replace it. Had it tested before I left and it passed but they couldn't tell how much it was putting out.

Installed it today, hooked everything up the way it was before and as soon as the negative cable was put back on the battery the alternator started smoking a lot. Disconnected the negative cable right away and it stopped. And yes, I'm sure I didn't hook the battery up backwards. I've found people having a similar issue on other non-turbo buick forums, but the responses are not too helpful.


It's safe to say that I'm going need another alternator, but any ideas of why this happened or where to start troubleshooting?

Thanks guys.

 

[Boost231]

Did you check the feed wire from the battery to the alternator? It runs along the front frame rail. Make sure it's not shorting out. Also take a picture of the back if the alternator please and post it

Sent from my SM-N910T using Tapatalk

 

[85supreme]

I did check the feed wire and its fine. Here's a picture of the back of the alt. Wasn't sure what you were specifically trying to see so hopefully this pic is good enough.

I also do have my fuel pump hotwired using the racetronix kit and have never had a problem with it.

 

[No disintegrations]

Possible shorted battery

 

[85supreme]

Tested the battery with a load tester and it seemed fine. Got 12 volts coming from it. Is that sufficient enough to rule out a shorted battery? Starting to think the alternator they gave was internally shorted out or something. When they tested it all they did was plug in the engine harness to the back and spun it. They never connected anything to the back of the alt to complete the circuit.

In addition, the new alt was the only thing that changed. The car hasn't even moved since replacing the alt the first time and now the second time when it burned up.

Unless there is something I'm missing.

 

[GNVenom]

Watch how tight your output stud gets when you install the ring terminal. Over-tighten it, and you'll short the stud to the alternator case, causing big fire and smoke.

 

[No disintegrations]

Possible shorted battery

Tested the battery with a load tester and it seemed fine. Got 12 volts coming from it. Is that sufficient enough to rule out a shorted battery? Starting to think the alternator they gave was internally shorted out or something. When they tested it all they did was plug in the engine harness to the back and spun it. They never connected anything to the back of the alt to complete the circuit.

In addition, the new alt was the only thing that changed. The car hasn't even moved since replacing the alt the first time and now the second time when it burned up.

Unless there is something I'm missing.

Id say the load test confirms battery good. They need to warranty that alt. There's a short in it if you are sure no cables rubbed through.

 

[No disintegrations]

Also they didn't test it right. As you said they need to complete the circuit. Black clamp onto alt case, red to stud then another to the control wire.