I have an 04 Polaris Sportsman 700.

Background on ATV:
3 years ago I was in a pinch and my fan quit working so I direct wired it to the auxiliary plug on the headlight so it is key hot.

ATV ran fine for 2 years and never over heated even when I was pulling heavy loads at low speeds.

Last year it overheated while pulling a heavy load. I blew out the radiator. Overheated again. When I say overheated what I mean is the "HOT" symbol flashed and it blew fluid out of the burp tank.

I took the radiator out and flushed it very well to where no fins were plugged. It overhead again.

Brought it to local Polaris Dealership. They found that the water pump impeller was spinning on the shaft. Ruined shaft so they put in a new shaft. Brought it home and it overheated. Called them and they said to put a new thermostat in. Took the old one out, boiled it and it opened around 170 if I remember right but put a new one in anyways. It overheated again.

Brought it back to dealership. They found that two hoses were backwards on radiator. They reversed the hoses and pulled another atv around going up steep hills and could not get it to over heat.

This was like September and I didn't used it for much until just recently. It overheated while just idling along at about 5 mph on level ground pulling nothing.

When it would overheat I would shut it off and turn the key on to turn on the fan to help cool down (fan is direct wired). Occasionally the fan would not turn on when the engine was hot.

My question: Is there something that when the engine gets hot that it cuts the power the the auxiliary switch thus causing my fan to kick off?

The local dealership has some awesome techs, is there something we are missing?

Any other suggestions?

Thanks in advance.

 

I "assume" you have the carb model with the Kokusan ignition and not the Ducati system as shown here.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse
Plus have you replaced the sensor in the radiator or do you still have the fan wired direct? If so excess running can shorten a fans life. The fan itself may have worn armature bearings causing it to stick. Have you checked for voltage to the fan when it stops? If it was at a dealer the sensor should have been replaced if faulty,plus there is a fan circuit breaker under the front panel also.Cooling system has to be really purged of any trapped air on this system. Most of the time the machine has to be raised at the front or tilted to do this while the radiator cap is off. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse Plus yes you can loose power either through a faulty/overheated circuit breaker by the battery,plus if it still has the the Ducati system not just ignition problems could happen,but stator output to the regulator itself could be weak causing problems. Is it charging properly back to the battery at an idle? A lot of questions for your questions.

 

It is an EFI.

The fan is still direct wired. Prior to the fan being direct wired it would run 95% of the time so I just left it. Additionally by having the fan run all the time the right side panel by the exhaust would not get so hot.

Fan turns really easy.

I don't know about the purging of air. Dealer would have refilled antifreeze twice so I am assuming they would have done that.

Don't know if it is charging properly however it does not have symptoms of a week battery. I have not put a volt meter on the alternator. As far as the battery it was new last summer. Old battery was original battery from '04.

The only time I have noticed any issues with the fan not working properly is after it has over heated. I guess the last two times it overheated on me I was using the atv for work and not paying attention to the fan but concentrating on what I was doing at the time. Also when it has overheated I haven't had a voltage meter handy. By just pulling it in my shop and letting it idle it will not overheat.

Thanks,

 

At least it eliminated the Ducati system. I'd check the circuit breaker located up on the harness that leads to the fan relay and fuse block. This breaker can either be taped to the harness or in a sealed plastic pouch. 800 efi machines had plenty of problems with this breaker,not so much the 700,but worth checking. Slice the pouch open,if breaker is corroded,replace it. It supplies power to the fan relay. If the breaker is weak/corroded,power to the relay cab be intermittent and the fan can short cycle or doesn't operate until the breaker cools. Another area is the fuse block itself. Had plenty of problems with these as the wiring under the block can loose good contact because of vibration. Pull it up and check all connections. Here's a post on an 800 that shared some of the same symptoms.http://forums.atvconnection.com/gear...r-heating.html

 

Thanks! I will do that. I will let you know what I find.

 

Check your boot between the carburetor and engine for cracks chances are its cracked and running to lean.