Hi Chaps,

As in the subject, I have a 2006 280 pro with a fan that kicks in at approx 165 degree's F but never then stops. With the fan spinning, the temp does keep dropping to 140's degrees's F (possibly more if I left it), so the cooling system is working. I suspect its the temp sender, but before I replace it, can anyone confirm?

I've confirmed on another bike (2004 250 pro) that the fan kicks it at around 170 and stays on until around 160. The 2006 should be stopping around 150-160, but it just doesn't.

(all temps checked with with a temp gun)

Cheers,

Wayne.

Best thing is it is cooling. Have you checked to see if it is wired to stay on?

I do not have specific temperature information, but I can say that the fan should be shutting off when the engine cools. Modern engines are designed to run within a certain temperature range. Outside that range, there will be a drop in performance as well as an increase in rate of wear of parts.

The temperature switches used in motorcycles relies on differential expansion of dissimilar metals to turn the switch on and off. after repeated heating and cooling cycles, the metals can deform and stop working correctly.

Engine temp is best done in the water, rather than externally. Using the infrared temp gun, it would be best to check on the outside of the cylinder in an area where the fan would not be blowing the heat away.

Check that the radiator is full. Low fluid can cause air pockets resulting in hot and cold spots which are definitely not good for the motor.

To test the switch, remove it from the bike and put it on a pan of cold water. Check across the terminals with an ohm meter. Cold, there should be not connection. Heat the water until the switch turns on. I suspect it should be close to boiling. Turn off the heat and let the water cool. When the water cools enough, the switch should open and the ohm meter should read no continuity. I would expect the switch to turn off in the 150 to 170 degrees F range.

Just replace the thermo switch or sender (which ever one you have on your bike)

If its faulty it might just stop working altogether next time out and boil up!

TLTEL