I have a 2003 700 twin sportsman. i was out for a long ride the other day , about 6 hours. We stopped about 5-6 times with no problems. The last time we stopped my quad was leaking anti-freeze all over. I took it home , then restarted it while it was still hot, the fan did not come on. When it cooled down i popped the radiater cap and the radiater was full, just the overflow spilled out. First i thought it was the fan so i disconnected the plug and ran a + & - lead off a battery to the plug and the fan ran fine. So it only seemed to overheat when i was stopped, when moving the airflow kept it cool enough. Then i noticed the there was a censor that was screwed into the bottom of the radiator and connected to the fan. So now i'm thinking that the censor went bad and its not telling the fan when to come on. Could you guys please tell me if i'm on the right track of troubleshooting this problem, thanks.

 

If the fan is not going on when antifreeze is boiling over you're on the right track. It has to be something electrical if you can bypass it and get the fan to run right off the battery. The best guy to ask is Old Polaris Tech. ATVConnection.com ATV Enthusiast Community - View Profile: old polaris tech Send him a PM. I'd love to help you but I'm not good at electrical problems.

 

I am not sure if it is the same as on the 500 but you could take the sensor out and put it in water and start heating it on the stove. Use an ohm meter and see if it changes. I can't quite remember but the resistance should go down as you heat it. If there isn't any change then the sensor was bad. OPT would be the guy who would know for sure.

 

The sensor is the hall effect sensor. About $80. I have replaced mine. Also, mine just recently over heated but it seemed to be from an air bubble being trapped. I would replace the sensor and then run the machbine with the radiator cap off to make sure all the air has burped. I raise the front end wih car ramps and jiggle the machine and squeeze the radiator hose to remove th air.

 

I think the Hall effect sensor is on the right front wheel and is hooked up to the speedometer.

 

Are you sure its not the thermal sensor. I went to a parts website and couldnt find the "hall effect sensor". Thanks to all for the help, much appriciiated !

 

Most of the time it's the thermal sensor in the bottom of the radiator,BUT make sure the radiator is clean,especially around the fan motor(good place to collect mud!) as it can over heat quickly before the fan even has a chance to kick on and start spewing out of the reservoir bottle.Plus as mentioned air bubbles can get trapped over a period of time if the cap is removed,coolant added,etc. Try as suggested on bleeding the air from the radiator with the cap off and front end end jacked up to help. Once the fan cycles on(if it does?) then usually the coolant level will drop and air expelled. If the fan doesn't come on before it gets hot,then probably the thermal sensor(I replaced quite a few of these) Plus don't hook up the new connector first and then screw in the sensor because as you screw in the sensor you can twist and damage the wire.PLUS there are two circuit breakers in sealed plastic pouches.Pop the front panel and see if you have power coming out the red wire on either side of the sealed pouch,if not then I believe the one under the front panel also ties in with the fan.The other breaker is the main power breaker. OPT

 

Thanks alot OPT , this sounds like the most accurate diagnose thus far. I will check all those things out and get back to you and let you know how i made out. Thanks again to all !