Originally Posted by Pokerrun388
Hard to say, it happens. It happened to me on my ‘13 MK3. I could smell coolant but see no visible leaks. Reserve tank kept loosing coolant over time. The car was still under the 3/36 so I took it into Ford & it was a faulty water pump.
Got it. In my case the leak is extremely visible (and audible...) but happens only and exactly when I turn the engine off. I can drive for hours with the tank remaining topped without losing a drop. Then engine off - wait 5 sec - turbulence, tons of pressure into the tank and tons of fluid runs out, practically emptying the res tank.