1992 Yamaha 350 big bear water in diff

[Jimjam]

Hi all, I have purchased a 92 (i think) big bear 350, that wasn't running, i have just got it running and now in the process of seeing what else is needed to keep it running and serving it. I was checking the rear diff oil and opened the filler plug and water came out. The question is how did water get in there without going back out the same way it got in?.

So I am going to drain it and put in new diff oil, what type of diff oil is best (viscosity) and how much is need for it? I'll do the front diff at the same time as the bike doesn't look like it has been maintained well.

[Richard1234]

I assume it's like a car or truck differential which needs to be vented to allow for expansion of the fluid with heat.  Thus the water gets in the top vent and can't get out. 

It means the quad got good and wet, as in sunk in water for a bit.  Same thing can happen to your truck when you back a boat down a launch, but more expensive, lol.    

[Jimjam]

That what I was thinking, but I thought I would ask just in case