2001 Sportsman 400.

If I just run her around in the mud, doesn't matter if I push her hard, she does fine.
When I get on an open flat trail and go twenty or 30 MPH for a couple miles, coolant will start squirting put of the top of the recovery bottle. If I stop, leave it running, I can watch the entire contents of the recovery bottle be drawn down to nothing, apparently going back into the radiator.

I have tried filling the radiator while it is running, and burping it....but what gives? It's no fun to stop every couple of miles and let the coolant jug go back into the radiator as opposed to letting it squirt out onto the ground...

 

Perhaps Old Polaris Tech will answer, I owned a 400 Sportsman once, and I think the trick was to jack the **** end of the bike up on jackstands, let it idle and warm up, keep topping up as it idles in neutral. My problem was exhaust catching the plastics on fire , plugged muffler.

 

Muddy radiators can cause plenty of problems especially around the back by the fan. Make sure this area is clean.Could be trapped air also,but also could be the 13 psi cap not holding pressure also.Clean the radiator front to back,jack the front end up off the ground with the radiator cap off to purge any trapped air,let the fan cycle on and off a couple times.Top off the coolant and replace this cap.You can get one at most auto houses and see if that solves the problem.

 

As crazy as this sounds, make sure the plastic plug under the overflow cap has a hole and it is clear...I chased an overheating issue for some time and it was that...

 

I sprayed my radiator out after every ride when I had a 2006 Polaris Sportsman X2 500. It overheated, even in winter. Dealer took the radiator out and the corners were clogged with hardened mud. It's the area where the radiator shroud covers the corners. Never had an issue after that. Once they cleaned the WHOLE radiator it worked fine. Just another thought.

 

Thanks for all the ideas!

OPT, I jacked up the front end, and ran it with the radiator cap off. The fluid slowly rose to the top of the radiator and began spilling out very slowly (not bubbling or anything, just a very slow gradual rise of fluid and very slow spilling over the top). I eventually shut it off as I didn't want all the fluid to wind up on the ground.

Is that what I should expect? AM I supposed to let it totally overflow until it doesn't overlfow anymore? I figured it SHOULD overflow, there is no longer a cap to keep the pressure and fluid in.

 

My overheating issues have almost always been radiator related. Even though you think it is clean, if you've been in the mud the radiator gets packed. I actually have had to pull my radiator out completely and soak it for days to loosen up all the crud in it. Then spray from the backside to completely clean out...

 

I am going to look at removing it myself. How big of a deal is it? Looks like the fan is somehow attached to it.
I also never like how little air is available to the front of it. By the time you get past crash guards and winches, seems like there is very little chance for air to get at the front.
Like others, I am sssoooo tired of the overheating, while my buds with Hondas never have that issue.
I will look at removing the radiator.

 

Have to remove the bumper,bumper guard and deflectors,remove the top mounting bolts and lift it out of the rubber grommet holes at the bottom of the frame.2001 Polaris SPORTSMAN 400 (A01CH42AA) Front Rack & Bumper Mounting | Cycle Parts Warehouse

 

not super hard just takes some time.