I just watched my quad boil over as the fan never kicked on. Checked the connection and found it was full of dirt. only made coonection part of the time. I did change the sensor when I changed the fan. I may have found the problem but the weep hole has started to weep again. Hope it was only due to heat.

 

the weephole leaks because of a bad mechanical seal behind the water pump impeller

Ron

 

if your fan isnt coming on when its surpose to it will be a problem. also make sure there isnt any air bubbles in there or it will scew w/ the sensor.

 

one other thing to check is that the filler neck isnt warped out of shape or that the sealing ring on top of it were the cap seals againist it isnt damaged it doent happen very often. but if it does it will cause coolant to blow out the vent hole on the resivior tank we have replaced 2 filler necks because of this problem .

 

Old Gray hair,I have a 04 700 efi and the next day after a mud ride I started mine up and let it run to warm up and didn't realize the fan was stuck because of mud at the bottom of the radiator.After a while setting there it begain to over heat out of the weep hole on the radiator resevior and I shut it off and filled the resevior with polaris anti freeze and after that day it kept running low every time out riding.So I put the back end of my wheeler on ramps and took off the radiator cap and let it run and watched some air bubbles come out and also I squeeze the hose and just let it run for a while then filled the radiator again to the top and put the cap back on and filled the resevior and it has stayed full since. My two cents.Mybe I just got lucky? But it worked for mine. Mudrooster

 

I'm having same problem with a 2002 sportsman 500ho it fine at idle don't do nothing but once I run it up the road it sprays out but once I stop it's fine no temp lights or anything