My lower hose of my car collapse i changed it still whn my car cool down the lower hose keep collapsing ? help?

radiator cap has three different seals(valves) to it. one keeps the coolant in the radiator and that is about all that it does, that is the gasket that is the largest and seats around the neck of the radiator. the second one is a pressure regulating valve. as the coolant heats up it expands. every cap is rated at a given pressure. a 13 lbs cap will release all of the pressure above 13 psi. all of the released pressure usually forces coolant into the over flow tank on a closed system. there is a third Valve in that cap that will maintain position until pressure in the radiator drops to an almost vacuum. then that valve opens and the fluid that was forced out of the radiator under pressure is pulled back into the radiator. i think that you need to ave that cap tested or the return path checked out. too much sediment in the overflow tank would leave you like this.