The Spring, 1995, edition of the old ST1100 Newsletter Magazine had a report from Brian Cescot where his cooling fan blade attachment to its motor loosened. This condition has caused a trashed radiator in at least one instance, according to the Winter, 1995, edition.
The problem occurs because the nut holding the fan to the shaft loosens. The motor shaft has two flats on it to engage with the fan. Everything will be OK for a while, but the hole in the fan will be wearing over time. In time, the fan will start to make a rattling noise. Eventually, the fan blades will be able to contact the radiator, damaging it.
The fan should be checked for looseness periodically. If it is found to be slightly loose on the shaft, tightening the nut (using Loctite®) may be all that's required. If it is very loose, it will have to be removed. Some J-B Weld® can be put in the bore and the parts reassembled. If the nut is corroded in place, you may have to destroy the plastic fan, but you should be able to re-use the motor.
Last updated on January 27, 2014 © 2001-2014 M. E. Martin, All rights reserved