Just check that you have 10V feeding the sender and not 12V. Your voltage stabilizer may be on the blink.

Was there a problem prior to you changing the sender i.e. why did you change it?
You could check it with an ohmmeter just to make sure it is not shorted. If someone has a spare one they could measure the resistance and you could check if it is the same, say in boiling water..... Or..The K likely uses the same sender so you could compare the resistance of your K and the clubman at room temperature.

OK. I get smiths part number: TT3001-8N or for BMC GTR-101.

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

From the pic there is no negative contact with the head with all that plumbers tape or the white stuff you used around the thread

The outside and threaded part is negative the wire contact is positive if I can put it that way

Don't worry about getting another one until you try that

I screwed mine In with that blue gasket sealent for water pumps just a little on the threads hasn't leaked for 3 years

Original Clubby temp gauges took a sender with black plastic insulation. No ideas what the part number was.
My Mini Car Clinic/Mini Kingdom book says Cooper S used a GTR104 until 1969, then a GTR143.
It also lists a GTR101MS as an equivalent to GRT143/GTR102.

Sorry, I have no idea of the impedance of any of these... (waits for minijcar to chime in)

Karcraft lists only a GTR101/3.

_________________
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.