I was hoping you folks could clarify a few thing in regards to the Ecoboost 3.5L cooling system. I had ask a question in a different thread regarding thermostats and you guys filled in the missing piece with the front engine shutters. My question is would it be normal for your engine temperature to be at 218* degrees with the shutters open and fans running at about half speed? I also also noticed the lower radiator hose leading to the thermostat as being cold as I would somewhat expect if not maybe warm. The passenger side hose from the engine to the radiator was hot. Another question I have is why would the fans be on when the thermostat should be open letting cool water from the radiator into the engine to cool. Why run the fans when there is coolant from the radiator available to do the job. I have the Lariat instument cluster with the numeric temperature displayed, so should the thermostat not be fully open at 218* degrees? I guess I am missing something. Thank You

 

Keep in mind that there is not an actual coolant temperature sensor. Engine temperature is monitored by the CHT (cylinder Head Temperature) sensor. The sensor signal is transmitted to the PCM. The PCM "interprets" (a word Ford uses) this information along with other sensor data to "calculate" a coolant temperature. This information is then passed to the IPC through the CAN bus for display. Since we don't know how the CHT signal is interpreted, almost anything might happen under different operating conditions.

 

Your thermostat is going to fully at its set temperature, about 195 irregardless of whatever else is happening. Fans come when airflow through the radiator isn't enough, usually when forward motion isn't enough as with being stopped. Upper hose will be hot as that is the coolant leaving the engine. Lower hose should be much cooler, cooled coolant entering the engine, continuing the flow cycle.