first off i just want to say I have electric fans on the car but they are not running at all... You probably all will say its my fans causing the problem but I am making sure cause I have a feeling its not. The reason why I feel its not from the fans is because the cooling system is pressurized and cannot boil am i right? if there was an air pocket in there it could boil? I Did the headgasket abuot a month ago, ever since then It seams there is a bubble I just cant get out of my system. I tried today on a slanted street and left my rad cap off for 30 minutes running, put it back on went for a cruise and my gauge goes up not up to red but up higher then what it should be and coolant was boiling, i can feel it thru the upper rad hose. I have no coolant leaks, every morning i check my rad and its filled to the rim. So no dissapearing coolant. As I said my fans are not working so I dont drive the car hard and its maybe 15-20 minute drives tops.