Temp Gauge/Over Heating Fault

[Andy 944]

944 LUX running faultlessly on way back from Cranleigh.

Temp gauge normally runs at halfway, if she gets hot it rises just over halfway, fan kicks in and settles back.
Gauge starts twerking like Miley Cirus, bouncing between half and three quarters and then off the scale.

I pull on to the hard shoulder. Car idles smooth 800rpm, 2 bar oil pressure (4bar+ under load), no other warning lights. No steam from under the bonnet, no loss of water or oil. water in the header tank is tepid, no boiling. squeezing top/bottom hoses produces movement in the header tank.
Radiator,Thermostat and Rad sender Switch replaced last year.

Nursed the car off the motorway, if I hadn't noticed the gauge I wouldn't have noticed anything, car driving as usual, no loss of power/performance.

Stopped at local watering hole and waited half an hour, returned to the car for the remaining 5mile drive home, needle still bouncing between half and three quarters.

Any ideas, poor connections, faulty gauge or something serious?

 

[ChasR]

How much is it dancing around? Jumping about like mental or smooth movement? If the former look up a few posts with the same title. The connections on the rear of the dash require cleaning.

 

[scam75]

+1. Easy fix.

 

[Andy 944]

Thanks - yes jerking about, not smooth movement, shall look at connections later

 

[wolfie308]

Mine's been doing something similar for ages, a tap on the binnacle sorts it out. Something else to fix when I replace the fuel low
level warning bulb and recalibrate the voltmeter.