hot altenator

My altenator gets really hot, had a dead battery from lights being left on. Charged the battery but now the alt. gets hot and only shows 12.5v on voltage gauge. any ideas? Is the alt. cooked?


Ago

 

It should deff. Be over 12volts! Get it running and disconnect the battery, if it keeps running the alternator is doing something...(I think thats a valid test). As for the alternator getting hot, thats new to me!

 

If you tried to bring the battery all the way back from the dead, you might have cooked the alt, or the battery. If the battery got messed up, it could show up as the alt getting hot and a low voltage condition...

 

Mine got hot and wasn't showing a charge last time out,,,,,,,,,,,checked the batt wire and it was loose and arcing,,,,,,,,,,,,problem solved

 

I had one that turned out to be a dirty ground; same symptoms otherwise. I would check there first then check the battery for a dead cell or low on acid.

After that I would open the alt and make sure that the bushings still have grease, could be that it worked hard enough charging the dead battery that it cooked the grease out of the bushings. Maybe clean up the end of the armeture where it is glazed over from the bruushes rubbing on it. While I was in there I would add a set of brushes that are not worn down to the nubs.

If it is still getting hot and showing low voltage I would change the regulator but maybe a trip to the shop would be in order.

Some fellas pull the batter cable to see if the alterntor is working but I don't so that any more. Just stick a screw driver to the little cap that covers the rear bushing if it is charging it is magnetized.

 

I think I'd take Jeff K's advice and either take the alternator or just charge the battery to a full charge and drive over to the gent he suggested.

 

Any reputable parts house should test the alt for free. however, as has been said, the batt could be toast as well. if it isnt maintenance free check the fluid in the cells and turn on accesories while trying to start (lights, elec fan...) to see if they dim/go out or put a multimeter on bat and have someone else start it and check for voltage drop.-stuart-

 

A ground would make sense to me...Maybe check and run a new ground strap from your block to the frame and check and or replace the ground cable from the battery to the frame!

porkn******...I never knew that cap would be magnetized thats a much better idea!

 

Ditto, what Mr48Chevy said.........For what it's worth, or not worth, we were told in auto electric cl*** to not disconnect the battery, with engine running.....Alt needs power from the battery, to energize the field....Unlike a generator, alternators do not have residual magnetism.....Which is why an alternator equipped vehicle cannot be push started, with a dead battery.

4TTRUK