Repairing a Lucas ACR17 alternator

[gmsclassics]

A couple of days ago the ignition warning light didn't go off, just went dim when I started the car and only went off completely after raising the revs to about 3000. I checked the battery voltage and this was well down until getting to those high revs.
I had a spare secondhand alternator (probably very old) so fitted that and the problem went away, everything back to normal.

Now the failed alternator is on the bench, is there a way of testing / confirming which part has failed so I can replace / rebuild? It is an aftermarket one c2010. I also have parts from another old alternator I could potentially use. Just need to know if they are any good. Some new parts are available here in NZ, but nowhere near as cheap as Ebay in the UK.

Any advice would be appreciated

Geoff

[yorkshire_spam]

You can test the diodes in the rectifier pack, but electrically that's about it.
If it was me, I'd strip it down - visually inspect windings, bearings etc. to make sure it's not wrecked. Then invest in a rectifier and stabaliser and rebuild.

[xvivalve]

…though the symptoms you describe could also be the result of a slipping or lose belt…

[Mad Mart]

You can get replacement parts like the rectifier pack & voltage stabiliser readily on Ebay. As said, you can easily test to see if the diodes have failed using a multimeter. Overhauling an ACR17 is quite straight forward but you will need a soldering iron to replace the rectifier.

[cleverusername]

Never done one of these because they have always been too cheap to bother with. Have done one for a Rover 75 because they are silly money.

I wouldn't bother testing anything, a full rebuild kits is £17, so you might as well replace everything. It is pretty easy, as long as you can solder. Though I would get a small puller to do the bearings, I found a normal sized one too big.

Anyway here is a video of someone doing one:

https://www.youtube.com/watch?v=ivIZsQbH728

[MIG Wielder]

Just as a suggestion I'd be looking at the brush box and its associated brushes first-off , on the end of the shaft. I'd also clean off the slip rings. These supply the all important field current to the alternator.
Part number for the 2 brushes is GGB 504 which I have been able to get in recent times.

Tony.