1968 cutlass S 350 automatic - p/s - no a/c
The rebuilt alternator that has been on the engine since 2019 failed.
This failure happened after replacing a defective battery with a new one.
I just got a replacement ( carquest rebuilt 7122a ) and installed it.
It failed in 2 miles.
The alternator got too hot to hold at the back end ( away from the pulley )
I am at a loss as to what to do or check next.
Please help with some suggestions.
Thank you in advance for your assistance.
Bill

 

Alternators can get very hot. Were there any other symptoms, is it charging and was the battery fully charged before installing the alternator? The alternator may have been producing high amperage to charge a weak battery.

 

Prefer to see data to validate failed ALT. With engine running, what is voltage measured at battery at idle & ~2000 RPM?

 

12.5 volts battery voltage only.

 

fully charged battery before both alternator failures

 

What is voltage at battery with ALT installed, engine running?

 

Internal or external? I bet the regulator failed.

Dead batteries kill alternators, and dead alternators kill batteries. They share a symbiotic relationship.

 

Could've just been a defective Chinesium part. Either the alternator or external voltage regulator if you replaced it at the same time. The alternator has a warranty doesn't it?

 

What is your idiot light or gauge doing during this?

 

Have the parts store test the alternator before you leave the store. That way you will know for sure if it's working properly before you install it in your vehicle. Do not assume that a new part works as it's supposed to.

 

Bill,
There was a thread the other day on one of the professional auto repair forums I belong to. Guy was working on a fairly late model For truck and went through 5 reman alternators that would not work right out of the box. Went and got a new one from Ford and it was fixed So dont be a bit surprised if it isnt just the junk parts available now days,

 

I put in a new voltage regulator. Seems the issue has been resolved. Time will tell.

The old regulator has a removable cover. There are what seems to be 2 adjusting screws, One is a black know at the top. The other is an adjusting screw that handles the spring tension for one of the contact points.

Is there a procedure to adjust these screws? Not that it is needed, but I am very curious.

Thanks again.
Hopefully back on the road for a long ride tomorrow.