My seicento overheated for the first time last night the cooling tank started to steam and bubble when i romoved the cap. i put a litre of water in but after 10 miles it happened again. i have flushed the cooling system compleately including the rad and checked for leaks but still the same problem after seconds! i also noticed the rad is still cold where the rest of the system is boiling then i took out the thermastat out and now water gets to the rad gets really hot but the fan doesnt kick in at all and the bubbling and steaming still happens. I have looked at past message boards and tried fixing it but nothing works can anyone help me????? please!!!!!! i am convinced it cannot be the head gasket wrong symptoms? PLEASE HELP THANKS!