Technical Temperature problem

[Dance2501]

Hello,

I have a temperature problem, I own a 899cc.
So I have swapped 3 thermostats, water pump, radiator and 2 temp sensors.
When im idle car works fine, around 90 degrees celcius the fan starts and stops spinning and the temperature stays perfectly around 90 degrees. But when im on the open road, my temperature drops to 70 degrees and only goes up when i stop at traffic lights, and right after drops back down to 70 when i speed up. I really have no idea what else could cause this except for the thermostat, and i believe its very unlikely all 3 were faulty. Could the radiator just be too large for the car? Not one mechanic has been able to source out the problem.

 

[firstcar-Y10]

So the temperature drops off when you are moving and rises a bit when you are stationary. Personally I'd diagnose this as perfectly normal, especially in winter. Don't forget if you are running the heater this time of year that is also bleeding heat out of the system, and more so on the move when the airflow increases.

 

[Dragon Man]

yeah perfectly normal for that engine, my 899cc cinquecento did the same thing.

 

[Dance2501]

I never use the heater, and this is also occurs in the summer with 35+°C, live in Greece. I have never had a car with an engine temperature flunctuating so much.

 

[firstcar-Y10]

I have never had a car with an engine temperature flunctuating so much.

... and now you do I'm sure it'll come up with some issues for you to fix at some point, got character these things, but don't lose sleep over this - really not a problem.

 

[GeorgeDamper]

The only things left are: Air in the system or faulty gauge.

I would replace the Expansion tank Cap

 

[FDNY21]

Both my Pandas do the same - don't worry

 

[deepblue975]

My understanding is that the gauge readings are from the thermostat/sensor at the radiator, which is logical to change with the motion air flow. If you want to know the water temperature in the engine, you need to read it via the ECU. It takes the readings from the temperature sensor at the engine block.