Faulty Alternator?

[steamy]

So this winter (yes I know its still winter) I have put a unleaded head on and Phoenix manifold and when doing job discovered a broken front mounting plate on alternator so put new alternator on.

Started her up and everything seemed fine in fact ticking over very nice. When hot after say 15 mins I increased the revs to about 3500 and all seemed fine for a while and then noticed the charging current was quite high at 15A then it showed 30A charge and engine ran very rough and revs dropped. I discovered that when this was happening if I put any load on like heater or lights the charge current dropped and engine ran sweetly!?

I left it to cool down and now from the start ammeter is flicking between 30A and 15A charge at tickover--used to be about 5-6A on old alternator.

Have I blown it up? Manifold has wrap on it but I do not have heat shield and back of alternator was 82 degrees c (leaser thermometer) Do you think I have cooked it or something else?

Sorry for long description of fault but new one on me.

Any thoughts or help greatly appreciated,

 

Regards

Ian

[TR 2100]

Ian,

 

I think you need to be more specific as to

the type of alternator you have fitted.

 

AlanR

[steamy]

Alan,

18ACR from well known source

 

Ian

[Ade-TR4]

Hi Ian,

 

I had a similar issue many years back with an 18ACR (my first IWE after getting the TR4 back on the road in 2004).

 

It overcharged the battery to the point that it boiled and started venting out of the filler caps on the cells. I suspect the heat fried the voltage regulator as there was nearly 20V across the battery(!)

 

Swapped the alternator (in the field at Malvern IWE!) for a recon Bosch unit and no problemski since. (It also cooked the coil, but that didn't go bang until the journey home!!!!)

 

Narrow belt conversion with a longer fan belt has allowed the alternator to sit further away for the manifold (plus you can heat shield, wrap etc etc)

 

Ade

Edited February 26, 2018 by Ade-TR4

[TorontoTim]

One good thing: if you still have your old alternator and if it is also a Lucas 18ACR then you could swap the front plate over from the new one (assuming that the old one was fine other than that).

 

I would have thought that wrap would have been enough to keep the alternator parts un-fried but I don't have any evidence for this because I also have a heat shield between manifold and alternator - just a mild steel sheet with a couple of strips of wrap held on by rivets (on the manifold side of the shield).

[steamy]

Ade, Thanks for confirming my thoughts. I havn't yet checked battery but every thing else appears OK.

 

Tim, My old one is a Lucas but not an 18ACR but front plate is same so today changed front mounting plate over and in process of making heat shield.

 

Thanks both for your inputs

 

Ian