Water temperature gauge

[MiniRebel]

My water temperature gauge hardly ever shows normal temperature usually it shows around a third then occasionally almost up to normal then drops. The mpg also doesn't seem to show much more than 31-34 mpg It's a 172 phase 2 it had been off the road for a while, it's had new spark plugs, stainless steel exhaust, and v6 air box, the water levels seem fine, the exhaust is black and could mean it's burning too much fuel

Are the temp gauges reliable on these cars, or is it more likely the sensor, thermostat and what's the best way to check. Otherwise it's running ok

 

[KevF182]

Probably thermostat... Depends how erratically it moves as to what could be the cause.

If you can visibly see the needle move up and down (like its jumping between different temps) then it might suggest a sensor or wiring issue. But if its just a tendency to read low, and only creeping up to middle under hard use, then its probably the 'stat leaking past the seal or sticking open slightly. I've had both faults at separate times - easilly solved.

 

[MiniRebel]

Yeah it moves slowly can do 10 miles and virtually no moment eventually creeps up after sitting in traffic but only to around half way, sounds like a new stat on the cards then, thanks for the info will try after I've had a quick look at instructions cheers, love this forum

 

[MiniRebel]

Finally changed thermostat only to find no thermostat actually fitted to the car, now I have car running better as it is now getting up to normal temperature. Should have expected as such knowing the previous owner! Car seems to be running about 6-7mpg better off at lower speeds as well. So all good