Hello everyone.. Thank you for taking the time to look at this thread.

My Kodiak is pushing oil out of the rear differential breather hose from time to time. It appears that when running the quad in four wheel drive under slight strain is when this occurs.

Example: I was riding two-up in about 6 inches of snow, under 15 mph and the hose started pushing oil.

As the manual states, the "Final Drive" (Yamaha's Fancy Name for a rear diff) needs to be filled to the brim when checking/replacing the 80 weight gear oil. Based on the manual, I would have to assume that the rear diff cannot be over filled.

I have checked the breather hose.. It is not clogged, or pinched, obstructed etc... I can only assume that pressure is building up within the rear diff causing the oil flow but the root cause of the pressure is beyond me.

 

I have heard about this happening before. I think you might be over stating it when you say that it can't be overfilled. When I do mine I add oil until it starts to pour out. Then I let it sit for a while until no more oil drips out. That will leave it full to the brim but not one drop more.

 

You fill up the differential until it overflows, it would not overflow if it was not full. Besides, when the breather hose pushes oil... Its not a drop or two.. Its probably close to an ounce.

 

Yes. Because the oil is thick, I believe that it is possible to over fill the diff by adding too much and then putting the plug in before the extra gets a chance to run out. This is not something I can prove, but so far it has worked for me.