Radiator Hose Upper R46521One New Aftermarket Replacement Upper Radiator Hose Fits John Deere 4000 Series Tractors This upper radiator hose (also called the top radiator hose) connects the engine to the top of the radiator as part of the cooling system on Fits John Deere 4520 and 4620 row crop tractors. Keeping coolant flowing efficiently between the engine and radiator, this hose is a key maintenance item for preventing overheating on these high horsepower machines.