does anyone have a problem with gear oil coming back up through the breather tube on the rear diff.?

 

You probably put too much fluid in last time you changed it

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99 Grizzly , Vamped & Liffed,Warn 2500 Winch

lumber1@rochester.rr.com, Ride safe today,because to ride again tomorrow is Righteous!!!!

 

I had noticed that my 98 Grizzly also had the differential fluid come back up through the breather tube as you have. (It's not hard to miss because it lands on the exhaust pipe and burns) I noted that when I have been riding high speed that it occurs more often. I have found that you need to measure the fluid when refilling the differential because it will hold more than the 8 oz. that the manual calls for. When I measure exactly 8 oz. and fill it will not overflow as it had, telling me that if you fill the differential to the bottom of the filler hole, it has too much fluid. I have also found that the rear differential fluid comes out dark in color whenever I change it and the front does not. Because of this I change the rear oil more often than the front. I still can't figure out why the front differential holds 20+ oz. and the rear is only 8 oz. Because of this the rear runs much hotter than the front causing the fluid discoloring. Hope this helps you out.

 

I had A 98 Grizz that would do this as well,I rerouted the vent tube so it would not land on the exhaust.I traded the 98 for A '00 Grizz and this one does it as well so I moved the vent tube on this one as well,I purchased A '00 kodiak for my wife and this does it to,I talked with the dealer and he simply said when the correct level is attained it will stop overflowing.I would say that the manual has to change its specs on fluid amounts.

 

Those who said your overfilling were
right, if you look on pg 8-8 of the
owners manual(98 Grizz), you will see a drawing
indicating the proper level of
fluid in the Final Gear Case(actually
I go a little lower.

The Front Differential(I also go a bit lower there also), is shown on
8-11(98 Grizz Manual), it takes more fluid
because it's a larger case housing a clutch
pack, were as the Rear is a basic Bevel Gear
arrangment.

Yamaha's manual Recommends SAE 80 GL-4 Hypoid
for both ends, I use a 80w-90 GL-5 in the
front and 85w-140 GL-5 in the rear both Hypoid, the heaver in the rear due to lower
capacity and the lack of clutchs.

A tip, those Pop Rivets used to hold the
Fender Extensions on do there job quite well
(hold the extensions on and in case of impact
break off b-4 fender damage occurs),
but if you look in the Cockpit area(lack of better term at this juncture) you'll notice,
the extensions are joined by screws(look for
the head you will notice them should be 12 of them), replace those with the Rivets(can get part #'s if needed) for an extra measure
of protection.

Great Day
Y2K