I have a 1998 magnum 425 and it keep pushing coolant into the over flow tank enough to leak out the vent cap and on the ground after it cools sucks the over flow just about empty and the cooling fan is coming on have checked for an air lock by cracking the tstat housing loose no air lock anyone no of any problem issues?

 

The Rad. cap could be bad. Don't give Polaris $35 for one. You can get one at any auto parts store for about $6 to $8.

 

Maybe bad rad cap not keeping its psi, the way to check for air lock,its to grab top hose and bottom hose.
If top hose is hard and hot, but bottom Rad hose is soft and cool ,you need to Burp/Bleed the air out of the coolant system.

 

If cap dont fix it chances are you have a bad head gasket

 

Thanks for the info I have tried to purge air but there was none in system rad cap good idea no external leak from head gasket and oil is clean just wondering if any one has ran into a thermostat or water pump issue

 

The nut on the water pump has been known to back off and thermostat can go bad too.