I lose a little coolant overtime Was getting bubbles in my expansion tank, and the coolant wouldn't pull back into the radiator once the engine cooled down it would stay all the full but radiator would be low. Have replaced the cap once already. was dead set thinking has to be the head gasket Welll..... Now I'm lost I got one of the block test kits to check for hydrocarbons in the coolant and I sat out there doing it for 20 minutes with a fully warmed up engine. It stayed blue the whole time....so now I'm not sure if its the head gasket or something else. Any help would be great.