12v system with 6v thermostat?

[Marcus van Bers]

So a PO converted my car from 6v to 12v at some point in its past. However, I don't think that the thermostat on the engine was changed because when I drive the car the gauge just barely gets off the needle rest, reading just under 100F. I've used a temp gun to check the engine temp and the highest I get anywhere on the case is just under 180F. Since the gauge does move I am assuming it is still working. I've read that one can use an inline resistor on the power wire to the gauge to drop it to 6 volts. I expect I can't just use a 12v thermostat from a 64 or 65C, or can I? So has anyone used the inline resistor and how exactly did you hook it up? Does this even make sense? Thanks for any enlightened commentary.

[David Jones]

Does the fuel gauge work as that is also powered by 6 volts. You can buy a cheap 12 to 6 volt converter cheaper than buying a new sender and getting it calibrated.

[Marcus van Bers]

Does the fuel gauge work as that is also powered by 6 volts. You can buy a cheap 12 to 6 volt converter cheaper than buying a new sender and getting it calibrated.

Thanks David. Oddly enough, yes the fuel gauge does work. I hadn't thought of that. I will have to see how they wired that up. There are two what I thought were relays next to the fuse panel. Maybe those are actually converters. I've seen pictures of converters that look identical to standard relays.

Is there a coloured wiring diagram for the whole car available somewhere? I know one of the members posted diagrams for specific things but I am looking for one for the whole car. The one in the owners manual is B&W and gives me a headache reading it. Thanks

[Martin Benade]

If you still need a source of 6v usually a resistor is not the answer as the voltages will vary wildly depending on current draw.

[David Jones]

Marcus, go the registry website and access the technical section. Plenty of colored wiring diagrams there.

[Mark Roth]

Marcus,
Here’s the link to the electrical diagrams in the Technical Library. You have to sign into the website to access them.
https://porsche356registry.org/content. ... _id=508436

[Marcus van Bers]

Marcus,
Here’s the link to the electrical diagrams in the Technical Library. You have to sign into the website to access them.
https://porsche356registry.org/content. ... _id=508436

Thanks Mark. I did down load those but I was looking for a schematic for the whole car, all on one page in colour. Those are great for tracing specific areas. I eventually did find a two page schematic which I will print in colour and tape them together.

[Mark Roth]

Greg Bryan has produced the wiring diagrams you are looking for.
https://www.vintagewiringdiagrams.com/

[Wes Bender]

To be technically correct, the title should be changed to read "oil temperature sending unit" rather than "thermostat".