I took the air filter out of my 850 yesterday and noticed about 1/8th" of oil in the bottom of my air box. Anyone have an idea as to what causes this? Is it a common problem with these? I took my atv in for the crankcase breather recall but I don't think they did anything with it. Maybe this is the culprit?

 

Not sure if you figured out the problem, but I had the exact same problem after i had the crankcase breather recall performed, apparently when they drill through the plastic, sometimes plastic pieces remain in the hole and clog it up...

Take it back to the dealer, I got mine all cleaned up and received a free oil change!

 

so it's still doing it! It is definitley coming from the crank case breather.

 

This may help Oil in airbox on 09 850 - Rubber Down Customs

 

I seen it happen on many ATVs,usually from steep hill riding,to much oil or if the ATV tips over.

 

well it's not any of those things I rode a dirt road all day and it was leaking there was oil in it that night. There is something different happening here. I think it is something with either the breather valve or the baffle in the valve cover (labyrinth)

 

ok guys I think I got this thing figure out. I pulled the valve cover off tonight and there is a plastic baffle called a labyrinth that bolts to the bottom side of the cover. your breather seals to the top side of this piece with an o-ring to keep excess oil from entering the breather. Well when you push the breather into position it warps the labyrinth and pushes it away from the sealing surface on the valve cover creating a gap that is letting oil splash on top of the labyrinth. polaris has changed the part number for the entire rocker cover assembly for 2010-2011 and if you buy a new one for your 2009 850 they send the newer part number. My guess is the newer part number is redesigned with different bolt placing so that there is more support on the labyrinth surrounding the breather area. I rtv'd the gap on my polaris and put it back together. I will keep an eye on it and see if it solved the problem. I figured that was better than spending $120.00 and not knowing 100% if it will fix the problem. I really hopes this helps you guys with 2009 850xp's that are getting oil in the airbox

 

I`ve been following this thread so please post up what You find with the repair.
I do`nt have a 850 but I just like to know,curious minds kind of a thing.