I have a 99 350 4x4,i removed the bolt at the top left of rear diff and a brown colored liquid spilled out!.
I looked for a drain plug but couldn't find it.(i removed the skid plate at bottom of diff but couldn't find a drain plug there).
How do i refill rear diff with the blue oil?.

I still haven't got my owners manual yet. (It's on order).

 

Sounds to me like your rear differential is full of water. Better check your breather tube on the pumpkin. If it's missing you'll need to replace it. Hope the brown stuff hasn't gotten to the gears and bearing in the rear differential.

Best of luck.

 

Could you please define "breather tube on pumpkin"?

 

Pumpkin is slang for the rear differential housing. There should be a small tube of about 1cm diameter coming out of the top of the differential and going up high somewhere on the rear of the bike frame. This is an air pressure differential vent. If it's missing then water can enter the pumpkin or differential through the vent hole.

 

Thank's

 

minehunter, i checked the breather,it's there and is as you said.

I think i know where the water came from,(a hole in the last cv boot towards the back).

How do i drain the water from the diff?.
I am hoping to save the gears and bearing in the rear diff.

 

First of all you the drain plug is on the bottom of the pumpkin. It should be the only bolt in the bottom besides the skid plate. Second get the boot changed. Then add just some 10w 30 oil and run it around your yard for about 10-15 minutes. Then drain again you might want to do this a couple of times. If you did get water in the rear end then you got water in the bearing. What model is your 350 4x4 (Big Bear or Wolverine). The gear oil is a brownish colors anyway not a blue I believe. At least mine is I use the YamahLube Gear oil. Now if it looks like chocolate milk then yes there is water. If your 4-wheeler is a wolverine than you will want to take the axle out and repack or replace the 2 outside bearing one on each side. If you go to Ronnies.com there is a Microfiche file on how the assemble looks. Just look up the year and make out your 4-wheeler. I know it sounds kind of intimidating taking the rear axle out but it is very easy. You just take of the right side wheel and hub (when you are setting on the quad it is your right). Then there are 2 bolts that hold on your brake caliper I think. Take them out and be careful of you brake hose not to kink it. Then the axle will just slide out the left side. This is how it is on a wolverine I don't know about the Big Bear. Get back to me if you need any more info. I hope this helps you.

 

You can also put kerosene in the differential and spin it by hand to clean it out if you don't want to use the 10w30 oil.