Hi there. I've got a similar problem on our s-max, water level dropped so popped some more in to bring it up to the minimum line and when I parked the car up after having driven it 15 miles I realised water was coming out of the water tank and leaking over the car park. Now the level has dropped quite significantly and it's so hot in the water tank that it's bubbling and steaming. This can't be normal right? What do I do? Head gasket gone??