This rubber radiator hose connects the engine block to the radiator, forming part of the coolant circulation loop. It carries hot coolant away from the engine to the radiator for heat exchange, then returns the cooled fluid back to the water pump. The hose has multiple internal diameters to match the different ports on the engine and radiator, ensuring a sealed connection at each interface. A cracked or collapsed hose reduces coolant flow, leading to engine overheating and potential gasket failure. The hose is molded to the correct shape for the routing path, so it does not kink or restrict flow during installation. On replacement, fully drain the coolant, clean the mating surfaces, and secure each clamp evenly to prevent leaks.