Some mk7 enquiries

How does a mk7 temperature gauge work , I’ve been told it’s not electrical . And what colour maroon was used on a 54 car . Or was it just called simply maroon ?

Correct, in this era Jaguar used mechanical temperature gauges which operate via a sensing bulb in the water jacket below the thermostat which is connected to a tube that runs to the fascia gauge. The tube contains a gas which expands and contracts depending on temperature. Not sure what the gas is, however.

Thank you john , the guage on the car in question is not working , could this be a huge problem ?

I believe the gas is ether, but I’m not 100% sure.

If a leakage has occurred and the ether has all gone I believe (again not 100% sure) that this can be repaired by specialists.

Many British cars (and probably foreign ones too) up until the mid 1950s used this method so you might be able to find equivalent parts which can be used to make a repair but again this would have to be done by a specialist.

Not easy to fix yourself.
Probably it needs a new capillary ( bulb ) and tube.
It needs to be gas tight and filled with Ammonia.
Send it to a specialist is the best option, or buy a new one.
You have a dual gauge, that also gives oil pressure?
Oil & Water Dual Gauge C2636/1E
SNGBarratt and many other suppliers are selling them.

Thanks for that Bob ,

Thank you Peter , yes it is a dual guage , I’ll check out SNG ! Do you mean they would supply the bulb and tube ???

No they will only supply a whole unit.

Thanks Peter , I’ll look into that

Hi Peter, I asked SNG for water temperature sensor and ancillaries , he brought up a choke otter switch . How can I be more clear ?

I would source an instrument repairer. I’ve just sent my gauge to be repaired as the water temperature part had ceased working. Cost in the UK - £95, VAT and return carriage on top of that figure.

Twice the price Canary paid but a new item rather than a repair. Whether a new item will be better than a repair is open to question.

Maroon or any variation of that color is not listed in the 1954 Salesman’s Data Book brochure, so most likely a repaint.

The temp gauge is a Bourdon tube, likewise the oil pressure. Most likely the tiny tube has a crack somewhere or may be cut off. Nisonger in New York is one place that repairs them for about $100-125 as I recall.
It is possible to repair your temp gauge yourself if you are good at soldering and can set up very hot and icy cold water containers on your workbench. I did it once using starting fluid which is ether, sprayed into a jar. I bought a roll of 1/8" copper tubing. Be sure you get the length right before you start, about 8 or 10 feet.

Search bourdon tube temperature gauge repair and you get a lot of hits.

Here is one about a '33 Plymouth.

and an MGB
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Hi Canary , thanks for that , did you send the whole shebang , or just the guage ? Where did you send it?

Thanks Rob , I’ll do the search ?

I have the complete gauge, Smiths number X42638/6. What has happened is that the ‘gas’/ether or whatever the medium is must have leaked out or lost its potency. I disconnected the oil part of the gauge and the water part at the radiator end and wrapped the water capillary into a loose circle, boxed it up and off it went to Speedy Cables in Swansea.

In the 1970s I saw a lot of these gauges with the capillary hacked off. Presumably that made the gauges easier to remove and replace the capillary in its entirety. These gauges are now pretty rare, so I made sure I had good insurance on the package.

That’s in my neck of the woods , did you have to wait long ?


I’ve just noticed that the one Barratt are selling has a different fitting to mine (off a 120). The picture of the Barratt one shows lugs, mine has a C-shaped flange.

I don’t know as it only went off last week. There doesn’t seem to much happening on the classic car front. I’m not really using the car, so not in a hurry. This firm actually manufacture replica gauges and I see they have a very similar (same?) one for a C-type Jaguar.

Yes, you should have an operating temperature gauge. Running a car without one could be dangerous for your engine. These can be fixed but you will have to thread the tube out from the engine bay to the facia gauge and remove the gauge. If a dual gauge you will have to disconnect the oil pressure line at the gauge. Nisonger Instruments, the long running Smiths instrument agents in New York, can do this for you. Contact them at 914-381-3600 or