Do NOT remove the thermostat- an engine relies on a positive pressure within the coolant system inside the cylinder head to prevent localised boiling of the coolant.
The 2002-2005 "black top" or "Focus " zetec engines are a bit of a law unto themselves.
They have the smallest radiator fitted, and the generic engine calibration map seems a bit hit or miss dependent on when the engine was fitted- and there's no rhyme or reason to it.
The engine map is not an automotive map- and was designed for stationary engines - ie those used as water pumps or similar....
Some engines run fine- others are lumpy and have poor response or off throttle RPM drop
Some run hot, others dont.....
There is no right and wrong here; however continued running at 100 degrees C plus may eventually "cook" the heat treatment out of the alloy cylinder head and lead to perpetual head gasket failure etc
This is one of the reasons we have recently redesigned our aftermarket radiator for this model to use a much larger core than standard to prevent any possibility of overheating under normal circumstances
Simon at Mulfab
