and while on the subject, in the oil clutch fans such as the 913c on the 9100 tractos and 9600 and R50 -52 combines ::: IF the fan has a dry rumble sound when the engine is shut of and the fan spins down, the problem that is starting is the spool the needle bearing runs on is starting to delaminate or score. During running the needle brg and spool turns at the same speed - thus no wear occurs, but after many hours the spool will get 'dimples' in it and start the 'rumbling ' sound. Replacing the brg will not quite the sound unless the spool n 2231685