Front Differntial failure L3940

[rScotty]

We are getting back into the snow season. I loaded the front mount blower a couple weeks ago and of course I'm checking everything very carefully, front dif, tires, etc. I do not want another problem that cost the $10K.

The tractor was home from the dealer repair last May. The front diff is dry, no leaks that I can see.

I did the winter oil change in mid October. Checked the front diff, no gear lube coming out of the test port, so I topped it up ... I think it took close to 2 qts.

I've been out a couple times with the blower now, checking the front diff each time, I think I've added another qt.

I called the dealer who did the repair, he thought maybe the oil was finally getting down to some of the areas in the diff that is hard to fill. He was alarmed about the 3 qts, advised it takes about 7 qts in total.

I have the tractor in my shop now, concrete floor and I'm putting cardboard under the front diff. I'm not seeing any drips.

I don't know where the oil is going! He suggested the rear seal but said they are very reliable. The front blower has a subframe so I can't see the pto attaching to the front diff at all. I wonder if the oil might be dripping onto the subframe and moving around although I do not see much on the floor.

I've been adding a 75w90 synthetic gear oil, the dealer did not comment on the gear oil so I'm guessing its OK.

It is so strange, the wheels are both dry, bottom of the axle is dry, any thoughts?

Should I change the oil out?

Thank you again.

Garth

Sounds normal to me. The oil has to slowly seep through the intermediate bearings to get out to the bottom bearings located at the far end of the axle.
That is why some of the outer bearings in the bevel gear end of the front axle are special type bearings without side shields rather than the more common type,

Those bearings are unshielded type - which enables oil to pass through. But even so, it passes slowly, because that viscous 75/90 oil takes a long time to reach a level. Yes, that oil is fine. Being synthetic type is even better.

If you are worried, see if yours has a bottom drain plug at the outer end of the axle housing just inside of the wheel. If so, that plug should be the lowest part of the outer bevel gear bearings. You might loosen that plug for an instant to make sure oil comes out. If so, tighten it back up and all is OK.
rScotty