New guy here.
I had to chime in here I have the 08 400ho as well & I checked it out & now have huge concerns of this as well.
It doesnt even look like you could run a tube from this for interference with the section where the (tie rod ends??) meet & pivot.
I will definantly check with the local Polaris dealer here in N.Georgia as well & post back.
Thanks for bringing this to attention.

 

is it possible that it is a check valve? Can you actually poor water in the hole? Has anyone tried. Don't give me this am I crazy answer. Cause if it is just an open hole then you already have water in it just by washing the mud off of them. I'd run some water in it and drain the fluid and see if any water is present before worrying too much. No, I havn't seen what you are talking about but it just doesn't sound right. If you have water in it then I'd go to my dealer and show him and let them deal with it.

 

Makes sense ncriderforks. We need some practical input.

 

nceriderforks-I have never seen a check valve used by an OEM for a differential vent. Check valves have a cracking pressure,which means the diff would become pressurized as it heated up,until the check valve "cracked" opened. I have seen pressurized diffs to keep water out,but they were still vented. Too much pressure can cause issues ,such as pushing out seals,and it doesn't take much. And lastly when the diff cools,especially when you dunk a warm/hot diff under cool water a check valve would pull a vacuum on the diff and just pull the water by the seals making a bad situation worse. Even the big mud bog trucks run a vent hose for this very reason,a check valve just will not work. Besides, A good quality reliable check valve would add quite a bit of expense over a fitting,clamp and hose. Also I go back to the Polaris parts schematic that clearly shows a fitting,hose and clamp. I would truly be amazed if it was a check valve would suggest removing it in favor of a fitting and hose.

 

i have not checked mine but it should have a vent but also should have a hose that runs up as mentioned. the wife has been in pretty deep water w/ hers so if there is a open hole there WILL be water in it. i'll have to check and get back to you.

 

Let us know Stendori. Too many people with the same thing for it to be a fluke build screw up...... Or is it? Let us know. Hey, I thought you quit or going to or something and so on and etc and you had died and know you are alive and your computer is broke and the connection was bad and you were mad and you know all the rest..... LOL

 

I checked this out some time ago since the wifey's Hawkeye has the vent tube running up to the gas tank, BUT my 400 HO has no vent or hole...it seems to be a completely sealed case! I would venture to say that it has seen as much water/mud as most on here and I have had no problems at all with it, the fluid is checked regularly and looks good!

I checked out the parts breakdown at the Polaris site and it clearly shows NO vent tube opening on the front of the housing like the Hawkeye has...look under "front gear case mounting" for the only clear diagram of the front of the case.

 

i checked mine as well last night best i could w/ flashliht and didnt see a vent tube or hole as well. maybe i'll look at it again somethime in the day light.

 

Look again guys cause its there on both machines. Can't see if it goes right into the innards. Its in the upper rear part of the case, right in the middle between the steering heim joints and is about 3/8" dia.

Any water in front diff fluids?

 

Jokout-I went back an looked at the diagram again and see what you are saying. If you look at the other diagram there is an unlabled fitting of some sort,too small to make it out,could be a zirk I guess? But then what is the hose and clamp for in the mounting diagram? I didn't think about the fact that the front case on the 400 isn't just a standard gear case but has the on demand components as well and therefore maybe isn't vented?
I looked and my front case on the 850 has no vent either but I assumed that is due to having ADC.