An apparatus for partially blocking airflow in a precleaner for an internal combustion engine may include a stationary barrier configured to be mounted in a precleaner. The apparatus may further include a movable barrier coupled to the stationary barrier and configured to move between an open position and a closed position in response to changes in an air flow rate through the precleaner. When the air flow rate through the precleaner reaches a threshold air flow rate, the movable barrier may move from the closed position toward the open position, and when the air flow rate through the precleaner drops below the threshold air flow rate, the movable barrier may move from the open position toward the closed position.