When driving my focus after 30 mins at 70mph or above on motorway car begins to overheat, never in the red about3/4 on the gauge, car goes to limp mode and when temp falls it pops out of limp mode and is back to normal, then drives for 15mins and happens again. Coolant is disappearing and mechanic said no faults showing up, head gasket is fine and can't find a leak!!! Help!!

faulty water pump not running as it should be maybe

Or maybe heater matrix - check drivers floor mat for damp.

Or expansion tank is weak and only leaking under pressure

 

Hello,

There is an official technical recall for the 1.0 (2012-2015) and 1.6 (2010-2014) ecoboost engine

https://www.ford.co.uk/support/how-tos/more-vehicle-topics/engine-and-transmission/how-is-ford-assisting-with-ecoboost-engine-issues

for more information, you can search the official Ford US NHTSA bulletin : RCRIT-13V584-6845.pdf

be careful on page 32, there is very important information : the thermostat must have an opening temperature of 82°C and no longer 90°C.

If you buy a commercial thermostat, there will only be 90° offered...