How do you test a thermostat, my cooling fan works but will not come on automaticaly.

 

i no to check it in a car all u do is take it out and put it in boiling water and if the spring opens it is good or closes on or the other it still works but dont know about atvs

 

Thanks rezrider, this thing looks more like a plug and when I pull it out coolant comes with it because my radiator is on the rack behind the occupants, go figure.
I'm comeing to a close on this thing and will no longer be on this site. But thanks for your help and responce.
I wish you good luck with your rides.