An experimental study has been undertaken on a railway vehicie cooling system in order to evaluate different noise control measures. The selected application is a large roof-mounted diesel engine cooling unit in the AGC (Autorail Grande Capacité) train. A strong presence of harmonic components from orders related to the 8-blade axial fan and the 7-piston hydraulic engine was found. ln order to reach a substantial noise reduction, the broadband part of the noise needed to be brought down as weil. A number of design modifications were proposed and tested in laboratory measurements: different ways to guide the air flow into the fans, reduced up clearance. absorption. vibration isolation of the fan and of the hydraulic engine.