Abstract: An air cooled internal combustion engine has the usual intake radiator housing in front of its suction fan. A generally frustoconical body is mounted for rotation in front of the radiator. The body is made up of radially extending deflector fins extending outwardly in convergent relationship and spaced uniformly peripherally apart to provide elongate air entrance slits between them. Mechanism drives the body in rotation at a speed to deflect particles seeking to enter the slits without materially decreasing the rate of air flow created by the suction fan.