The reasons for this abnormal noise are as follows:
1. Due to the vibration of the diesel generator fan blade, the rivets between the blade and the fan blade hub are loosened. The fan mounting screw is loose. Cracks developed at the roots of the fan blades, changing the pitch angle of the blades. Broken fan blades, etc.
2. It means that the fan pulley fixing bolts are loose or the screws fixing the fan are loose and need to be welded or replaced in time.