Have suddenly had temp guage reading low (checked with temp guage gun) and looking at swapping for another that I have lying around. Also have a spare guage as well.

Realize that it may be the voltage reg but wondering what ttype the temp guage that is fitted to my car is.
It seems light a solid metal wire coming out.

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

Isn't that a capillary tube for a mechanical gauge?

I haven't checked the fitting to the temp guage but it is a very old VDO with degrees Farenheit marked.....

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

If the connection between the *gauge* and the sender is a capillary tube, then it is a mechanical gauge not an electrical gauge. Try Googling VDO mechanical temperature gauge and see what appears.

Definitely Mechanical.

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1960 Morris Mini Minor

yup, capillary tube mechanical. They are cool. Try find a replacement

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

Hopefully the sensor and tube are OK as nothing unusual has happened before the low readings.....

The gauge still reads well, just cooler than the actual head temp. I imagine the voltage regulator is causing this, and it might just be dirty connections......

Will get to it this weekend.....

Thanks all for the info.

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

If it is mechanical the voltage regulator will have no effect. It gets the temperature reading by expansion of ether in the bulb that screws into the head. Only has wiring for the backlight.

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The voltage regulator doesn't get involved in your gauge and sender. Yours are mechanical; not electrical apart from the backlighting of the gauge..

Mmmm didn't realize that. What would cause the slow or low reading? Loss of gas or fluid from the pipe?

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

My understanding is that the Bulb in the head and the tube all the way to the gauge are filled with wax.
As the bulb is heated the wax expands and pushes through the tube and deflects the Bourdon Tube in the gage which then pulls the needle around.
Are you sure it isn't just running a little cooler now that it is autumn.

Edit, corrected the spellink of Bourdon.

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Find a job you love and you will never have to go to work !

Seems to take much longer to warm up.......read that these mechanical systems either work or don't......

The temperature reading seems to be slow to change.......

Could be the lower ambient temperature I guess, combined with a fresh batch of coolant mix.

Will fix the last piece of the cooling issue (after new thermostat, waterpump, radiator flush) with a radiator core rodding as the car still seems to overheat.

I can then see how true the gauge is then I guess.

Anybody know a reasonably priced radiator place in the north of Sydney?

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

I use Blacktown Radiator repair shop,
14/27 Forge St, Blacktown NSW 2148

Last one a few months ago was $150. He's a 1 man band but does a good job.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc!

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

The tube is full of ether not wax which expands under pressure and deflects the Borden tube in the gauge. Simple test Unscrew the bulb from the thermowell... no water will come out don't worry then put the bulb in a kettle.

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1960 Morris Mini Minor