i have an early model 2004 polaris sportsman 500 H. O. that constantly overheats. i have done a number of things to try to stop this but still no luck. i have:
-replaced head gasket
-removed thermostat
-thoroughly cleaned and relocated radiator to top of front rack
-completely empty all coolant and replace with new
-mechanical seal behind pump fins
ok so i recently did the radiator relocation and i now have more issues than before....
the quad now will not accept coolant. it will but EXTREMELY slow(with it running) i pulled the bolt off the side of the pump to make sure coolant was flowing and it SPEWED out of there like crazy and very hot but the radiator stays very cold. my radiator is very clean. not the problem. i do not have a thermostat so flow should be max at all times. not the problem. i have a brand new head gasket installed. not the problem. i am stumped. what is stopping the system from allowing me to install coolant and why is it not flowing???? thanks for any help!!

 

Mine was over heating and I tried everthing, turned out it needed nothing but a airlock burped out of it. You can tell if it has a air lock,the top rad hose will be hot and hard while the bottom is cool and soft.
The two hoses should both feel hot and hard with the motor warmed up and running.

Another thing is get the rad cap pressure tested at a rad shop I think its suppose to be rated at 13-16 psi but not sure ,I cant find my manual.

 

Welcome to the forum! Sounds like trapped air,plus is the fan kicking on or getting hot before it does? Just fill radiator,leave cap off while running until fan kicks on then any trapped air will be expelled through top of radiator. Relocating radiator can make it even more time consuming to remove all the trapped air. Also I would put the thermostat back in! I had several "mud bug" riders that relocated the radiator on top of the racks that had the same problem. OPT

 

the only problem with doing that is it will not take any coolant. literally the radiator is and all lines are dry and there isn't much in the system so i dont understand why it will not let me put any fluid in it! i can put a very small cups worth in it and then run it and wait 3-4 min and put another cup...repeat...repeat. i could be here for weeks doing it like this... and also the lines are both cold and the coolant coming out of the pump area is extremely hot. like its not circulating but has tons of pressure...

 

Sounds like the lower rad hose may have separated internally and is closing off. Worth taking a look at, happened to me. Different vehicle but same concept

 

it is a brand new hose. i pulled the return line off and filled everything as much as it would let me and it is running much better now but still no still lines. im going to try to burp the system tonight.

 

Can you do a pressure test on the system? Why am I thinking your water pump is not pumping?

 

im thinking the same. maybe i dont fully understand the system though...water pump not working means the impeller wouldn't be turning but i know it is because if you purge the system by pulling the small bolt off the side of the cover where the incoming and outgoing lines are, it spews coolant very fast! i rode it last night and it seems ok but it wasn't very warm yesterday so still worries me. does not having a thermostat affect the return pressure? i assume it would only increase the pressure which should be a good thing...

 

Put the thermostat back in,check for any kinks in the coolant lines that would cause coolant restriction,also if you didn't tighten the water pump impeller tight enough after you replaced the seal,it's possible for it to just spin on the shaft and not be able to circulate coolant and spew back through the radiator! Also anytime you remove a hose,replace a thermostat, work on the water pump etc, you introduce air in the system and it must be purged by leaving the radiator cap off. Plus relocating the radiator will just take extra time to bleed all the air because of the hose length. If all this checks out,but still has problems,then could be the radiator itself partially clogged! Plus does the fan ever kick on? You said you have the early model which has just a regulator/rectifier,not the centralized awd system that had the ecm recalls, and your awd is in the hubs? OPT

 

My friend has a 04 sportsman and it has the centralized awd .

When I burped mine,I slowly added coolant while shaking the ATV with the front wheel jack up 5" off the ground, that was my clymer manual instructions.

Might be harder for you with your rad on the rack not standing srtaight up and down.