I have replaced the water pump, timing belt, thermostat, cooling fan and everything that has to do with the coolingfans to tell them to turn on. I have also checked to see if there is a blockage in the radiator nothing. the upper hose get hot and hard from pressure and the lower hose is cool to the touch and no pressure. when the car runs the over flow tank starts to bubble and the overheating light comes on. help am lost. thinking it maybe the head or head gasket.