912 electrical problem....help please!

[JAN]

Hi,

My '67 912 has broken down. started with dead battery, but to be fair i hadnt started it in a couple of weeks and it sometimes does that. Thinking the battery was a little tired anyway i replaced it with a new calcium 45Ahr hobby from halfords (strangely old one was 36Ahrs...but manual says should be 45).

All was fine, but got home after 10 min drive and could smell burnt electrical smell coming from engine bay, generator was very very hot and smoking from the pulley end. Regulator was also very hot. Even with engine off and ignition off it heats up really rapidly. so i have to leave it with the battery disconnected.

now when i connect the battery the ignition lights come on, but i just get a solonoid slicking kind of sound, but i dont think its from the starter motor, might be from regulator???? hard to tell, but starter makes no signs of life and the battery is full. If i leave the battery connected the generator and regulator both heat up and the generator starts smoking very quickly.

what the hell is going on? Could really do with some help on this.

Cheers
Jan

[Nige]

I'd get a sparky to look at it. Sounds like either a shot regulator which can cause overcharging or a toasted generator or both as one can take out the other. If you're getting problems with battery connected and the ignition off it sounds like you have a meltdown in the wiring somewhere that is causing a short. Any half decent autoelectrician should be able to find the fault, you don't need a Porsche specialist.

[JAN]

any more for anymore? how much are were do i get a new generator and regulator from?

ta

[Nige]

think regulators are pretty standard and can be bought new from your favourite car spares. Generator wise, not sure if they are VW units, I suspect they are? I'd just get it refurb locally.

Surprised nobody else has suggested anything.

[FMAN]

Jan,

As Nigel said, I would get an auto electrician to look at it. It sounds like you are a short step from an electrical fire. If the ignition comes on when the battery is connected something has already failed/melted. I wouldn't connect the battery again until you find out what.
Measure the resistance to ground from the positive battery cable (battery disconnected), if it isn't open circuit try disconnecting the suspect parts until it is. That might give some indication if it component or harness failure.

Regards

Neil

[Mike Smith]

I think that the reason that nobody else has suggested anything is that - it really is not possible to analyse this sort of problem by mail

I think Nige is probably (?) correct the Reg has taken the Dynamo out or vice versa----- BUT
(1)- What other damage has been done to the wiring ?
(2) - Why did it happen ?

As others have very wisely suggested - it really is a job for an
auto-electrician although he won’t necessarily be cheaper than a Porsche mechanic

Be careful just fitting any old regulator - The Regulator `does what it says on the tin` - It Regulates
If it is set to demand more power from the Dynamo than the Dynamo was designed for, you have meltdown

Unfortuanatly, our experiance of 356`s and 912`s is that the wiring has always been dicky`d with and it is very easy to spend 2/3 days (and longer) sorting out the debri left by others

Mike at PR

[JAN]

thx. do you know if the parts are the same as t1 vw please?

cheers people.

ps dont worry, the battery is dissconnected!

[JAN]

surely i can fit a bosch 12v early bug generator and reg? Anyone know any different pls?

[JAN]

surely i can fit a bosch 12v early bug generator and reg? Anyone know any different pls?

[Ian Gunney]

912's had two types of generators - the early ones (like yours should be) are small and the later ones are larger in diameter. I ended up buying a refurb'd unit from Roger Bray about 7 years ago and it was expensive then. They aren't the same as VW ones (as far as I am aware) but please correct me if I'm wrong!

[louis356]

I'm 99% sure that they are NOT the same as any VW item. Or you would see others with them and a conversion from 6-12volts on 356 would be easier.

Good luck but there is a spaghetti bowl of wires to go through

Good luck and tell us the outcome.