recently my truck began overheating, i changed the thermostat, made sure all fluids are full, no crack in hoses or housings, still over heats- last night it blew the filler neck apart from pressure- what could have caused this- oh the upper hose was hot as hell, while lower hose was cold to the touch

 

Need a new radiator cap and not the type with the lever on top as these are closed systems.