Here's another fact to mull around...at 4 k...youre moving enough air without the fan to cool the motor. Clutch fans don't need to run above those rpms, fans help at low speed and idle, after that it's all wind cooled with the vehicle speed. A good indicator of a problem is when it overheats at cruise, capacity issue or blockage..
Yes thats clear i just thought the will get damaged or so when you spin them more than 4000rpm















