GM 94amp Alternator
 

I bought a 94amp alternator from John's Cars a while back and it's performed flawlessly charging at 13v up until yesterday. It's now jumped up to 18v at anything above idle. It drops back to 13v at idle. Anybody have any ideas? The battery is about 3years old.

I don't see how it can be anything except a voltage regulator failing

But I'm just two sips into my first cuppa coffee :)

Cheers
DD

And that's onboard the alternator itself - right?

Bill,
How did you mount that GM unit and how does it interact with the XJ6 wiring/idiot light etc.

It was a direct bolt in relaxing the Lucas with same wiring

Just re-read the below chat about "Ignition Light Remains On". And Jeff even talks about 18v if the battery is going bad. MAYBE that's my problem!!!??? The date code is 2/16 and it does get pretty hot here in Florida.

I do not see the connection between excess alternator out put and a failing battery???

but, I sure understand the word "electrickery" ! I did not coin the word, but admit to popularizing it!

So:

1. Swap in another battery and see if the 18v continues?
2. Check the battery. :Include a load test.
3. Warranty on the alternator?

Gee, Doug, I'm rationed to one cup of coffee....

Carl

Yup, you're right, not the battery. Still getting 18v with a new swapped in battery. I guess that leaves the voltage regulator as the culprit?

Bill, I would get that taken care of right away. We were at a car show and a guy with a modified 57 Chevy that had the battery in the trunk told me that his alternator went crazy and the battery either boiled over or exploded, I can't remember which. The result was battery acid all over his pristine trunk.

Thanks Jeff. I already parked it and ordered a rebuild kit. Only bad things can happen with 18v!

Sometimes it's pretty obvious why something is wrong. This seems to be one of those times. Note one of the brushes is broken and the capacitor is detached from its wire and the housing burned. Glad I have a complete rebuild kit on order.
https://cimg1.ibsrv.net/gimg/www.jag...2fa827da7f.jpg

Emailed Johns Cars with the above picture and he is sending me a new one with an apology! Now that's what I call SERVICE. I'll keep you posted.

!. Some folks criticize John and his business plan. I am not one of them. I was always well treated. this is what I would have expected. The best advertising one can get in business. Stand by the product.

2. As I recall, John sells a part that adapts to the IL 6 to enable the Delco to bolt in. Hence, your comment as to a direct bolt in. I do recall a fellow on another forum doing so by subbing in the Delco for the air pump!

3. Somewhere or another, I have ajar of Delco alternator fix parts. I fixed one for my V* roadster.A deviation from it's all 40's theme. A frame, Flat head v8. T body and 35 Ford wire wheels... Oh, and a 32 B grill....

Carl, I sure hope you can share a photo with us of your T - A - deuce - flatty!

One of the ones I let go that I wish I had not!!! and no surviving pictures either, oh woe is me..

Carl