A cooling fan for an engine in a vehicle. Ordinarily, a fan rotates within a shroud, which surrounds the fan. Leakage can occur between the tips of the fan blades and the shroud, wherein fan exhaust moves forward, and then passes through the fan again. The invention reduces leakage by placing a surface downstream of the fan. The surface employs the Coanda Effect, to urge fan exhaust to continue in the downstream direction, and not move forward as leakage air.