What is the oil level in the front hubs of M7040 or similar size Kubota?.

[sixdogs]

In filling the front hubs of my M7040, what is the oil level you should fill the front hubs to? The owner's manual is fuzzy and just says to fill until you can see it but the wheel is in the way and you can't see anything. Would it work just to open the check hole on the axle and since the axle and hubs flow together any excess oil in the hubs would drain out that way? What do others do? I'm stumped.

 

[moriboy]

Take both plugs out of the axle and fill thru the upper hole until fluid starts to flow out of the lower one. Add oil slowly so it can flow to both hubs. If you add too fast, oil will come out of the lower hole before it has time to settle out into the hubs.

 

[oosik]

This particular area of draining, filling & checking has always seemed a bit like black magic to me also. My M6040 is the same as your M7040. So with everything drained and all drain plugs replaced - first I fill the front axle gear case up to the top of the fill plug hole and install that particular fill plug. Next I fill the front differential case up to the check plug hole and install the check plug & fill plug.

If I check the front differential case oil level an hour or so later it will be a bit over full because some of the oil has drained down from the axle gear case into the differential case. I've never worried about this and its never caused a problem.

I'm just glad that there aren't any more fill, check or verify holes in the front differential/axle gear case assemblies.

BTW - I did a quantitative check on the "extra" oil in the front axle assembly after it had sat a week or so. I opened the check oil level plug on the differential case and a little less than 1/4 of a cup came out. That's why I'm not concerned about overfill.

 

[sixdogs]

Good advice and here's why I ask. This is a new tractor and when I got it, I checked the center axle and it was fine. Then I checked the hubs and added some because the owner's manual said to add until you can see it. After that, I didn't bother to check the center axle and later discovered it to be overfilled. In fact, it was blowing some oil out the vent hole. Oops.

So, if I add oil to both the center axle and the hubs and then add oil, they will flow together and the excess drain out the center check hole, right?

 

[oosik]

Yes, you are correct in your statement six dogs. When all is said and done, mine looks like this - - the oil level at the fill plug on the front axle gear case is a little bit down from spilling out the fill plug hole and the oil level at the differential case check plug hole is a little bit(about 1/4 cup) over full.

I would guess if a person didn't understand what was happening and gauged the entire operation based upon the level at the front axle gear case fill plug hole - you could end up over filling the system - since the front differential case and front axle gear case are all tied together.

 

[sixdogs]

oosik---My center differential check plug is out and the oil in the side gear cases used to be near the top of the hole opening but now is much lower. I can't see without taking the wheel off but it's down there since I stuck a piece of wire in and jut got a tip of oil down more than an inch or more. Not sure how far till I check again.

Does that sound normal? That by letting the oil drain down with the plug on the center axle differential out and the oil just draining down to it's natural level? For some reason I was under the impression the side case gear oil was supposed to be higher. If I added more to the hubs it would flow out the center hole if open or overfill the center differential if plugged. Maybe I should try adding a little more like you do--but then wouldn't I be overfilling?

 

[oosik]

Black magic, mon, black magic. You know - I'll just bet if I went out and checked the oil level in the axel gear cases it would be down quite a bit - and the check hole on the differential case would show over full. Give me a minuet and I will go out and check. OK - I'm back. The oil level at the fill plug on the front axle gear case is down 2.25 inches from the lip of the fill plug hole. I loosened the check plug on the differential case and oil was coming out even before I could remove the plug. For all intents and purposes I think that indicates everything is full.

If I were to add more oil to the front axle gear case - it would simply drain down into the differential and create more of an overfill condition.

 

[sixdogs]

oosik--thank you.