suddenly my car starts overheating? Turn it off for a short while then it seems ok again for a while. any suggestions?
Provided you have checked the coolant level and it is okay.
The only suggestions is take it to an independent mechanic or, due to the complexity of the C-Max, take it to your dealer to have it diagnosed. You may to pay for the diagnosis, but a proper diagnosis is cheaper than guessing.
It might be something simple as the thermostat.
I agree with Purebread. I would also suggest a comprehensive review of all the service done and the service needs of that very modern vehicle. 7 years is a good time to check the unusual stuff is being properly maintained.