Alternator Overheating?

[bobcowan]

Wierd problem recently showed up.

After driving for a short while - like an hour or so - the car dies. It's not quite like turning the key, it sputters a tiny bit and then dies.

I happened to catch it on a data log. Just before dying out, battery voltage rapidly climbs to 20v, and then the car shuts off. It probably trips the breaker for the ECU, which controls fuel and ignition.

That started about two weeks ago. I replaced alternator and voltage regulator. That seemed to fix it, until 2 days ago. Then it hasn't done it until today.

It seems like something is overheating. It only occurs during the day, when it's hot - like 90-95*.

What are the symptoms of an overheating alternator?

[vector1]

if you have unused front brake ducts run a hose from one to the alternator and see what that does for you.

[madmaxx]

Besides bearings and brushes nothing to overheat. Brushes have little mass so they dissipate heat quickly

[CowtownCobra]

Bob, you might get your battery checked.

[bobcowan]

The alternator gets pretty hot to the touch, but they usually do. The voltage regulator is on the firewall, in a spot that doesn't get much heat. I'v been driving this car for 7 years in the same configuration, and never had a problem.

I installed a new alternator and regulator a couple of weeks ago.

I tested the battery - both static and loaded, hot and cold. All tests came out well within specs.

[vector1]

bad ground on the regulator?

[Rick Parker]

Check the regulator, is it the right one for the alternator. It may be a bad Voltage regulator thet is keeping the alternator in full charge mode unneccessarily.
I had this happen with a mechanical Regulator the points were sticking. If you have the later electronic version, there may be other issues. Check the compatability.

[bobcowan]

It's a new regulator, so probably not bad. But it could be, so I think I'll change it and see what happens. The ground is good - it's bolted directly to the firewall.

Tonight I fabbed a simple alum heat shield for the alternator. Might help, might not. But it was free, and worth a try.

I'm starting to think it might be the ECU. I'm going to try and configure my LM-1 to log volts. Then if it happens again I can try and log the volts independent of the ECU.

[Rick Parker]

While on alternators....I had my head under the hood of a new Malibu Hybrid a couple of days ago and noticed that they have heater sized coolant hoses going to the alternator in an attempt to keep it cool.