Hi all

1275cc. Morris 1100S. Standard radiator. Metal 12 blade fan. Thermostat temp unsure yet. Temp sensor standard. Gauge as pictured, unsure where it's from.

When I'm driving a constant 50-60km/h the temp gauge shows quite low. But when I sit stationary at the lights, I can see the needle creep up every 5ish seconds, until it sits at approx 3/4 mark. It never moves beyond this though. When when I start driving, the needle will drop and sit near the "C" mark.

Should it be moving around so much? It seems a bit sensitive to me. I've earthed the temp gauge and the needle reaches the "H" so I'm assuming that's ok.

What should I be testing first or is this ok?

Cheers peeps

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Australian 69 DeLuxe w/ hydro suspension. Single HS4 (twin HS2 being assembled). 1275 1100s engine (998 due for rebuild) . Clubman remote gear change. Automatic front subframe.

I would confirm the temps you are getting to start with. I use an infrared temp gun. Then you can do a guage adjustment. Here is a guide on the adjustment. http://www.mgb-stuff.org.uk/fuel.htm

Thanks. I will check the coolant temp against a temp gun. Don’t have one but I can get a hold of one.

What about the range of movement? And the sensitivity?.... or is that related to gauge adjustment?

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Australian 69 DeLuxe w/ hydro suspension. Single HS4 (twin HS2 being assembled). 1275 1100s engine (998 due for rebuild) . Clubman remote gear change. Automatic front subframe.

I have not played with many gauges but i found one adjustment was for the position of the needle and the other one appeared to be for the sensitivity. I am sure one of the instrument gurus will be able to confirm. Howard instruments is one that comes to mind

Your gauge should rise when you idle after a run...unless your coolant system is absolutely over engineered for your car...go for a good run then stop and see if the radiator is bubbling into the overflow...

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"Show me the Mini!"

Australian made Smiths gauge fitted to Australian MK II series Minis such as the Mini K and Cooper S.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Fabulous!!! Nice work!!! I can’t seem to find many pictures of them on the internet.


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Australian 69 DeLuxe w/ hydro suspension. Single HS4 (twin HS2 being assembled). 1275 1100s engine (998 due for rebuild) . Clubman remote gear change. Automatic front subframe.

Check to see if the two cork plugs are in place in the back of the gauge where the adjustments take place. The gauge is bimetallic is: it heats two dissimilar metals to cause a deflection of the needle.
If the plugs are missing and you drive along forcing cold air into the gauge it will read low. Stop and it will read warmer. Julius Sumner Miller would be saying from his grave “ Physics my dear boy...Physics”

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1960 Morris Mini Minor

+1
I must be slipping. I totally forgot about that.

Agree, even with the plugs they are sensitive. In winter if I drive at content speed I can wind my window up and down and the gauge moves accordingly due to more cold air finding it's way to the back of the gauges. Insulation at back of instruments may help.

Also these gauges rely on a constant regulated voltage and the old fashioned voltage regulators at back of speedo are not very consistent. Does your fuel gauge also fluctuate? You can get electronic voltage reg. replacements.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Interesting. Whilst I've been working on the mini, I've folded back the bulkhead insulation so I can see straight into the back of the instrument binnacle. I can also see the two adjusting holes are uncovered. Gaffer tape time.

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Australian 69 DeLuxe w/ hydro suspension. Single HS4 (twin HS2 being assembled). 1275 1100s engine (998 due for rebuild) . Clubman remote gear change. Automatic front subframe.

more info , My CS does the same, I fitted a new temp gauge no change .I rang a gauge shop in Newcastle they do a lot of minis. I have the car booked in .the technician told me it will be a bad earth,
Allen

I had the same problem but with the fuel gauge. You could stop at the lights and watch it come back up.
So I ran it to 100kmh on car stands and it didn't do it.
Problem was body vibration and the 1950s technology voltage stabiliser.
An electronic one from 'wombat' on here fixed it.

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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.

The trick is to address one possibility at a time.

Earthing (or voltage drop) is a fundamental problem that is quite simple but often overlooked particularly in a low current circuit like gauges.

The cork plugs are a unique problem that I have come across due to the design of the mini.

The original voltage regulators are fundamentally a reasonable idea in themselves but they are affected by a poor earth as they rely implicitly on a reference to earth.

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1960 Morris Mini Minor

Had to use Blu-tac to plug the holes as too much work to get any tape to stick.....

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