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Discussion Starter · #1 ·
Hi everyone, I inherited a polaris 400 about a year ago. Last time I took it for a ride up north the headlights gradually got dimmer and dimmer until it stalled out. I used the pull starter to get running again. The next day I pull started it again and went for a short ride and noticed the engine was overheating...coolant bubbling out of overflow. Went and got new battery, still overheats. Got it home and jumped the fan directly to a battery...it works fine. I learned from the forums here to replace the heat sensor that plugs into the radiator (autozone model), so i did that. I did have to splice the new sensor to the original connector since the new one was not compatible. I refilled the radiator with coolant and did my best to purge all the air. STILL OVERHEATS and the fan still does not come on. Is it air in the radiator or bad waterpump. If waterpump, where is it and how hard to replace. The new battery is now dead from sitting all winter, would another new battery cause the fan to run? Any advise would be appreciated, thanks.
 

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Welcome to the board!:cowboy:
 

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welcome to the board , if its the fan not coming on then thats got nothing to do with the water pump. the fan only comes on when the heat sensor calls for it. so thats not it if you fixed that. did you flush the fins of the radiator. this is a common thing for sportmen they get filled with seeds and mud and such and to clean it right take the screen off in front of the radaitor, and flush with garden hose.try that if you havent already .
 

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thats what i was thinking that the fins were cloged. i know that everytime i wash mine a lot of junk comes out of it
 

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is battery charging? take a volt meter put on the battery ,rev up motor a little should have 13.5 to 14.5 volts , if not regulator is probably bad, black box in front of radiator,
 

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Mine was doing the exact same thing, I rpleced the temp sensor AND thermo...still noluck, but when I replaced the radiator cap, the fan came right one and the overheating issue stopped. Try that..
 

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Discussion Starter · #8 ·
overheating resolved..but..

Hey everyone, in frustration, I finally took my overheating sportsman 400 into the sevice shop. The flushed and refilled the radiator, replaced the temp sensor at the bottom of the radiatior (the one I installed was the autozone model-they put in a polaris part) I also had them put in a new battery while it was there. (my last battery died just before my 400 started overheating). So anyway, I pick up the quad and everything is fine, no overheating, starts right up. So i take it on a trip and everything runs fine for a day and a half. Then, one time after about two hours of heavy riding i switch the quad off, and it won't restart - dead battery. (just like the time the overheating issue started). This time, no overheating after i pull started it, but no headlights, taillights, and i assume no power to the fan. The outdoor temp was pretty cool this weekend, is the overheating and battery problem related? If not, why is my brand new battery dying so quick?
 

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Im having a similar issue with my 05 sportsman 500.
you said in a earlier post that your lights and power started dimming then stalled out. Now your having a similar problem and it intermittent. Check the kill switch assembly. Sounds like you have corrosion in there. Which explains alot of your problems with it not starting and stalling and yes even the coolant fan. If your PCM doesn't have a good enough of a signal from this it will cause all kinds of non related problems.
what year is your bike? Some of the Polaris have circuit breakers or fuses. Check for those as well.
I fought mine for 3 days because everything was testing fine! Then the headlights wouldn't turn on and I got into that assembly. There was so much corrosion that I could hardly get it unplugged.
I found. A crack ion the circute board. That controls all the functions. Now mine is good as new.
hope this helps. If you have any questions you can Pm me and I will try to answer. Them for you.
I bought a new assembly on Ebay for 79 dollars.
 

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check with a volt meter at battery to see if its charging, should read 13.5-14.5 volts when reved up alittle, if not its usually the regelatio, black box in front of radiator
 

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I have same issues and I did some troubleshooting and it seems to be the radiator filler neck warped and the cap not seal properly.
 
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