temperature guages 1800S

Can anyone tell me whether the oil and water temp guages on the P1800 and 1800S are capilliary guages (ie reliant upon the expansion of a fluid within a pipe from the senders in the engine to operate the visible bit on the guage) and if so, what is the fluid used in the pipe (industrial alcohol, mercury or something else)? I have two guages (one on the car and one spare) and the water temp doesn't work on either of them. My son is a calibration engineer and he recons that if I can find out the answers to the above, he should be able to fix and calibrate both guages as the mechanism is very simple.

They are but i'm buggered if I can remember the gas they used

Filled Thermal System Guages! 

Alan; They are indeed capillary tubes, and they are filled with ether...I suggest you immerse both sensors into boiling water as a check before doing anything else...because calibration will require removing the chrome surrounds to gain access to the internals...often, the oil gauge doesn't even come off the peg in normal duty...it's therefore presumed broken...but often the oil temp doesn't even get into the indicating range of the gauge...if the system is compromised and ether escapes repair is possible but involved... Cheers from New England

Ron / Mike Many thanks for your replies. I have placed both probes in a pan of water on the stove. The oil temp guage moves niceely through the range whereas the water temp doesn't move at all; and the water temp should produce a reading far earlier than the oil temp in any case. In both of the guages I have it is the water temp that needs attention. For those who have not explored the innards of the combo guage: to get access to the mechanism, unhook the six tabs at the back of the chrome surround and remove, then undo the two screws that hold the guage mechanism into the metal backing case. It's a surprisingly simple mechanism inside, (springs and gear cogs) all driven by the expansion / movement of a flat (hollow) tube (coiled like a spring) as the ether (thanks Ron) expands. I will report in due course on progress with repairs. Many thanks once again.

Have a look at Andrew