my sportsman 400 repeatedly overheats after a few short minutes in some light snow (about a foot), or in light mud or marsh. Its only been doing this for the past year, after we adjusted the carb to get it to run in winter (-20 celsius). all the cooling parts work fine, no leaks, pump works, and i've returned the carb to it's previous setting and it still overheats. any ideas?

 

What's your altitude and what type of coolant do you have in? One of mine overheated in 32Deg weather but I was at 15,000FT and did not change my coolant type and of course the boiling point changes W/ Altitude.
Other than that is your radiator clogged?

 

Your radiator my be cloged w/ mud, it happend to my quad.

 

i think it's about 2100 feet, 900 metres, and i've pressure washed the rad, and the rad warms up when it's running so the coolant is moving...but teh cooling fan doesn't run when the "HOT" light comes on, but it works when it's just normally running.

 

Hmmmm, Maybe the temp switch? if the fan isn't running when the light kicks on it should override and run....

 

it's probably the switch...and i just spent a few hours driving and adjusting the mixture on the carb everytime it overheated, but it still does it