Abstract: The invention provides an engine cooling system for a water cooled engine in a motor vehicle, comprising a radiator 18 totally enclosed within ducting such that air flowing through the radiator does not otherwise pass through the engine compartment. The radiator 18 is arranged within a branched ducting with two outlet openings, one branch being fan 20 assisted and the other opening into a region 28 of low pressure at the front underside of the vehicle. An undershield 22 serves to enclose the engine and separate air flow paths are formed for cooling the oil sump, the top of the engine and the exhaust manifold.