antodrm

Hi everybody, I'm Antonio from Italy
the issue with my W204 is that on an uphill road higway the temperature gauge swings up to 120°

Even if in winding roads for example Amalfi coast with much traffic the temperature remains normal.

I noticed also that after a long trip the cooling fan continues running.

I can post links of the videos I made from youtube

Thank you in advance

C300Sport

I'm assuming you have checked the coolant level...
Has the cooling system been checked/serviced recently? Possible failing thermostat?

antodrm

Thank you for the prompt answer, the service told me also the thermostat works.

Do you any other suggestion?

C300Sport

If the thermostat is opening and you still have climbing temps while the engine is under load...

Water pump is failing?

Radiator and/or coolant passages in the engine are clogged and not allowing enough coolant to pass through. Could do a "flow test" on the radiator. Is the coolant nice and clean looking? If so, I would doubt it's a clogging issue...

Josh.A.Hussey

Check ECT. It reports the temp to the ECU