(T) new owner, low temp reading

well i just bought a little 1996 cento for my daughter who will be 17 in a few months. ive decided to run it as my own car until then as my normal motor (3000 v6 pajero) only does 17 mpg...!
WOW what a great little car to drive, i was smilling all the way home.

i did notice though that the temp gauge stayed at the 50 mark all the way back, the heater was blowing warm air into the car but not really hot.
this makes me think that it might be a sticky thermostat. sticking in the open position. are they easy to change. also the car has done 56 thousand miles and seems in really good condition, a little tappety just for a few seconds when you first start her up.

50C sounds low, operating temps should be in the 70 to 90C area really. A sticking rad thermostat would increase coolant temp not decrease it as the radiator & heater core wouldn't be cooling the engine properly & the temp sensor should be the engine side of the thermostat.

The two Seicentos (not Cinquecento that you have) I've experienced never really get hot on the motorway at 60 to 70mph unless you're doing 20 or more miles, you have to drive them where you're accelerating a bit to get them to warm up quickly but once warm they'll stay warm.

Not necessarily a thermostat can stick open as well as closed meaning the car takes longer to warm up and if its cold outside maybe never reach full operating temperature

Bah, wasn't thinking properly

Pretty easy and cheap job (flexible drive recommended on 1100 engines!).

But does the temp guage move at all?

Might be worthwhile checking that there is actually a thermostat in there!!

I've known people to take them out and forget to put them back in when selling cars.

Yeah easiest way to make an engine that runs a bit on the hot side run colder.

Mine ran luke warm when i first got it and when i changed the 'stat i found that the old one was stuck about 3mm open. Everyone else on here was on about their centos running hot/overheating/doing headgaskets and after 15 miles on the motorway the heater was only tepid

If the thermostat is stuck open, and it sounds like yours is, it is easy to test for.

Let the car cool off. Start the engine, and feel the radiator.

If the radiator warms up slowly, the thermostat is leaking or missing.

The radiator should stay stone cold for 10 minutes or so then suddenly, over 10 seconds or so, get hot, too hot to touch. This is because no water should go the the radiator until the engine is at temperature. When the correct temperature is reached, the thermostat opens and the radiator fills with hot water from the engine.

If you get the thermostat out, even a tiny gap in the valve when it is cold is bad news. It should be totally shut.

Noise from top end could be worn hydraulic valves or worn valve guides. Do an oil change with the correct grade of oil & genuine oil filter - this may help if the old oil has been in there a while.