Electrical Hot alternator while ignition is in the on position

Swhitney

Active Member
Feb 11, 2019
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Oregon City
I had to move the car in my garage, so I turned the ignition on (engine off) to push the car around. I forgot about the key being in the on position until I came back a few hours later to smell something a bit strange. What I found is the alternator was hotter than hot, and now it seems like the bearing is toast in new 130 amp alternator.

What would cause the alternator to heat up?

1992 Mustang GT
302 engine
130 amp alternator (Amazon)
 
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That alternator has an internal short. Good thing you weren't driving it when it happened. If the battery connection at the alternator is loose it'll cause the stud to get hot. Usually, the alternator would have to be running for that.
 
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That alternator has an internal short. Good thing you weren't driving it when it happened. If the battery connection at the alternator is loose it'll cause the stud to get hot. Usually, the alternator would have to be running for that.

So you think it's not something else? Brand new alternator has a short, seems strange right?
 
Not strange at all. Quality control is way down. Something shorted inside that thing....or got so hot that it melted and shorted out. Dodge had a problem with this recently. Their cars would catch fire because of it.
 
I had a relatively fresh 130 amp alternator cook the + post and connector on the back of the alternator. Im not totally sure what caused it but the alternator was not a cheap one. I had gotten it from one of the Mustang specific vendors. I replaced it with a DB Electrical unit which I got from Amazon. I've had no trouble with the new one, albeit I also upgraded the wiring.

Here's the one I have now. It may need to be clocked to use on the Foxbody application. It's still a decent price I think.

Amazon product ASIN B007XUIF52View: https://www.amazon.com/gp/product/B007XUIF52/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1
 
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I had to move the car in my garage, so I turned the ignition on (engine off) to push the car around. I forgot about the key being in the on position until I came back a few hours later to smell something a bit strange. What I found is the alternator was hotter than hot, and now it seems like the bearing is toast in new 130 amp alternator.

What would cause the alternator to heat up?

1992 Mustang GT
302 engine
130 amp alternator (Amazon)
The alternator field is energized when the ignition is on. Turn ignition on & any steel item will stick to alternator case.