A guiding device for use with a fan-radiator cooling system wherein the fan is upstream from the radiator. The guiding device comprises a series of guide vanes in combination with at least one guide ring. When placed between the fan and the radiator, the device improves the heat transfer capacity of the cooling system by directing air flow through the radiator center, a region that typically suffers from reduced flow due to the air flow pattern in and around the fan hub. Furthermore, the guide vanes align the air flow from the fan so that it is generally parallel with the axis of the fan. The guiding device permits greater heat removal with a given fan and radiator without increasing the speed of the fan.