Ford Mondeo engine temperature gauge goes cold over 50 mph?

Question

I have a 2001 Ford Mondeo automatic 2.0 litre zetec. Everything has been fine until recently when the engine started going cold when I drive on the motorway or anything over 50 mph. It doesn't suddenly drop, it gradually goes down from warm to cold. I have switched it to circulate the air in the car, and the car gets warm at normal speed and the gauge is on "normal" but as soon as the speed picks up, the temperature goes down - it is driving me mad. The garage want £306 to fix it, but they can't tell me what is wrong before it has been on the diagnostics (and extra £56)!!

Any ideas about what it could be and how to fix it would be appreciated. I am eternally optimistic that it will be something simple that I can fix myself!!!

Thanks for reading this!

CG

Answer 1

THERMOSTAT CONTROLS THE TEMP. IT IS STUCK OPEN.
REPLACE IT. THAT BE THE ONLY THING THAT WILL DO IT.

Answer 2

Measure the engine temperature at the thermostat housing with a non-contact IR temperature meter. If the engine temperature is below specification at road speed, replace the themostat. I'd replace the thermostat anyways to eliminate that unknown.

Answer 3

Sounds like you need a new thermostat,you could put a piece of card board in front of your radiator to block off the air coming Thur it.Keep a eye on the temp Gage so it doesn't get to hot.

Answer 4

Thermostat is stuck open, probably takes longer than usual to warm up also. Replacement is E-A-S-Y. Almost anyone with tools can and would do it for $50 USD.

Answer 5

Check the coolant level. If it's low, the water pump could be drawing the level below the sensor at high engine speeds and it would read cold.

Answer 6

probably the thermostat, but have you checked your water level?