Replacement Butec Alternator

[Dave123m]

Hi,

I'm hoping someone may be able to assist with a spare alternator they may be willing to sell or any advice regarding a source for rebuild parts as since I took the car out of storage last weekend unfortunately the Alternator appears to no longer be charging despite all being fine when stored.

I have checked the alternator wiring / brushes & all appear to be in good order however have not yet investigated the operation of the Regulator.

Does anyone have a spare alternator before I investigate something more modern or should I just go for an upgrade without repairing the current alternator?

Thanks in advance for any assistance or guidance.

Dave.

[vee12eman]

Hi Dave,

I have both a spare alternator and regulator, however, I am holding on to them as spares, so not much help. However, I had similar problems myself (hence the fact I bought spares!) and when I did, I looked into alternator and regulator repair, both achievable at home. Repair of the regulator is tricky and probably not worth it unless you are slave to originality; a very similar looking unit is available as a replacement from the usual suppliers – this consists of a Leece Neville (the original manufacturer) unit, modified to have the original contacts and a original appearance data plate attached.

The alternator is a pretty tough design originally intended for commercial vehicles. It is relatively easy to test, the procedure is described in the Jaguar Series 3 E-type workshop manual. I tested following this procedure and found it better to use a 12V DC power source (e.g. a battery!) and bulb as test results with a multi-meter can be misleading.

If the windings of the alternator stator and rotor are intact and insulation tests are successful, plus tests prove the 6 internal diodes are functioning correctly – i.e. passing current only in the intended direction, the most likely culprit is the externally mounted triple diode pack, this can also be tested and again should pass current in only one direction.

Replacement diodes are available and although replacing the internal diodes is tricky, the triple diode is pretty easy although a little difficult to source –I found one eventually.

The first time my alternator failed, replacing the triple diode cured the problem, much cheaper than a replacement alternator. I had however, already obtained a second alternator, which is how I obtained a spare, both my alternators are now confirmed functional.

If the tests described check out then it is probably the regulator. I say probably, as I had a later system failure. Swapping to my second alternator failed to cure the problem, so it must have been the regulator, right ? Wrong! I ordered a replacement regulator and the system still didn’t function. Testing both alternators confirmed no problems, so I checked the system once again. This, more careful check revealed the earth for the regulator was corroded and whilst it had passed a simple current check, it wasn’t good enough for system operation. That was how I ended up with two serviceable regulators.

There is another item in the system to check – the dash charge indicator bulb. If this lights when the key is at RUN with the engine not running and fails to go out on engine start, it is fine and the problem is elsewhere in the system. However, if it fails to light up at RUN, with the engine not running, then check the bulb, if it fails, the alternator does not charge.

I wrote up the experience in an article for the E-type club, which shows how to test the alternator , with photos, I can email a copy to you if you wish, I can’t simply attach it to the forum as far as I can see. If you want this, send a pm with your email and I can fwd a copy of the article.

If you end up needing a replacement alternator because repair of yours is not possible, then I think I still have the receipt for an English company who can repair/exchange an alternator somewhat cheaper than a replacement from a Jaguar Specialist and I could look up the details, I think they are still a going concern.

Regards,

Simon

[MarekH]

I have spares.
Send me a pm.

kind regards
Marek

[Dave123m]

Hi Both,

Many thanks for your prompt offers of support & assistance, I will drop you a PM as suggested.

Regards,

Dave

[Djerome60]

Hi Both,

Many thanks for your prompt offers of support & assistance, I will drop you a PM as suggested.

Regards,

Dave

Hi Dave,

by any chance do you still have your spare alternator? I might be interested to buy it.
regards
Jérôme

[Dave123m]

Hi Jerome,

I sent my original Butec Alternator back as Part Exchange, Marek may still have spares though?

Good luck in your search.

Dave.

[Djerome60]

Hi Jerome,

I sent my original Butec Alternator back as Part Exchange, Marek may still have spares though?

Good luck in your search.

Dave.

Hi Dave,

thanks for your reply.
Cheers.
Jérôme