Series 3 Alternator on the way out?

I've had a few gremlins behind the dash in my 1974 2.25 petrol with recent example being the ignition warning light being on even with the key removed, and before I knew that was the case the battery unsurprisingly flattened over a weekend. Even with the light on, the battery was being charged properly with 15v plus according to my voltmeter with engine running. I've fiddled a bit and now the light only comes on at key position 2 but stays on and the battery is around 13v engine running, 12.8 with engine off. As far as I can tell all alternator connections are good

My question is how hot does a properly functioning alternator run at? Mine is too hot to touch after only a few minutes with the engine idling. I suspect it is failing gently if not with a bang
Any insights very welcome thanks

It should not be that hot.Could be a bearing on the way out or problem with voltage regulator/rectifier.

15v seems a bit high to me.

Redlight on with ignition off is a failed diode pack in the alternator.

I suspect with an alternator that gets that hot that quickly it will be (more than) apparent there is something wrong when you remove the V belt and try to turn the pulley by hand.

tottot is probably right - sounds like the diode pack is buggered. You can replace the diodes and regulator but it's a bit of a faff. Either replace or get it refurbed at an auto electrician (if you can still find one). The lucas alternators were used on a lot of old Brit cars so a trip to a long established breakers may source one.

Many thanks for all your comments, very helpful. I now have a new service exchange unit which I'll fit on Wednesday touch wood. Hopefully all the connections will fit without needing change and that I can do the job from above without too much grovelling on the gravel which it's parked on

Grovelling eh?

(Probably not the best form of attack!)

Ahhh....the luxury of gravel I can only dream of.
Try lying on broken bricks

Flossie said:

Try lying on broken bricks

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broken bricks? i dreamed of laying on broken bricks. i used to work on cars laying in cess pit back filled with fish guts and broken glass

Flossie said:

Ahhh....the luxury of gravel I can only dream of.
Try lying on broken bricks View attachment 130828

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See the Pikeys made a nice job of your drive

Well that's the replacement alternator fitted, what a palaver to get the pulley and fan off the old one! Now charging at about 13.5 volts which seems better. The old one's bearings were fine so overheating must have been electrical. I just hope there isn't still a battery drain to earth I don't know about. Anyway many thanks for all advice. And at least the gravel was dry

I think it should be putting out 14.5 volts

Col

Dont want to hijack the thread, but as anyone had an alternator overhauled recently?
I have one that I want to get cleaned up and brushes changed then swap out for the one that's fitted,

raywin said:

Dont want to hijack the thread, but as anyone had an alternator overhauled recently?
I have one that I want to get cleaned up and brushes changed then swap out for the one that's fitted,

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Although I've never had to do it it doesn't look too difficult to do yourself.
Just need a soldering iron (iirc).
Replacement diode pack etc are cheap , £16 seems to ring a bell?

Flossie said:

Although I've never had to do it it doesn't look too difficult to do yourself.
Just need a soldering iron (iirc).
Replacement diode pack etc are cheap , £16 seems to ring a bell?

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Did wonder about that, might be interesting to give it a go,would like to find a solvent to wash out the winding's and clean it all up, I remember using one called safe sol which was intended to use on varnished winding's of electric motors.

Just about to do the same job. Landy failed to start on Monday see my post. Alternator is about 10 years old so probably knackered.

Getting the nut off the old alternator was a real pig as the spring washer had been completely flattened. I had to get help from a pal with an air driven wrench and a big vice to grip it in, plus big levers to stop the armature rotating. Plus it was a 21 metric nut when my kit is imperial, and undoing and redoing the (overlong) mounting bolts one flat at a time was a real bore!
I'll recheck the voltage tomorrow with a few more revs. Old alternator was a Quinton Hazell unit probably from 1999 when a complete Turner engine was fitted, new one was allegedly Lucas, from a Transit

raywin said:

Did wonder about that, might be interesting to give it a go,would like to find a solvent to wash out the winding's and clean it all up, I remember using one called safe sol which was intended to use on varnished winding's of electric motors.

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Most decent auto-electricians will do it, if you don't fancy the job ....