Kubota B26 blowing oil from vent

[3Ts]

Make sure those filters you replaced are seated properly.

 

[sixdogs]

Not sure if you mentioned it but my B7800 gives different transmission level readings. One when it's cold and the other after it's been run a while and warms up. When I check it cold and before it starts, no fluid shows on the dipstick. When I warm it up and check it, I get a reading. Had I filled it to a "full" reading on the dipstick when cold it would likely be very overfilled when warm and would likely blow oil out the vent tube. I have seen this happen..

I still want to rule out fluid level as that has been the only reason I have seen Kubotas blow oil out of the vent tube. Just my free advice.

 

[wagne223]

Not sure if you mentioned it but my B7800 gives different transmission level readings. One when it's cold and the other after it's been run a while and warms up. When I check it cold and before it starts, no fluid shows on the dipstick. When I warm it up and check it, I get a reading. Had I filled it to a "full" reading on the dipstick when cold it would likely be very overfilled when warm and would likely blow oil out the vent tube. I have seen this happen..

I still want to rule out fluid level as that has been the only reason I have seen Kubotas blow oil out of the vent tube. Just my free advice.

This is good advise and completely true, however in this case the OP stated the fluid is foaming.
Foam equals air intrusion.

 

[woody]

My thoughts from afar, what I would do with the same symptoms, after replacing filters with OEM parts. You have a 10 year old machine, the following is cheap and relatively easy maintenance in the scheme of things, and will help to fix, or rule out some bits. The most likely cause of aeration is the suction elbow, remove and physically inspect, squish/feel/replace, if at all hard or any sign of deterioration. However there are a couple of other orings in the circuit, and are worth doing while you are there. Remove suction line and oil filter housing, replace oring to tank and oring to line. So order the parts, fit them, and see if any improvement. The drained oil can be put back into tractor, run it through a sheet if any debris has dropped in it. YMMV.

going to be busy so I probably will not have time right away but this is exactly what am going to do, Thanks

 

[rScotty]

Make sure those filters you replaced are seated properly.

Even if the filter isn't leaking to the outside, the nipple it attaches to might not be seated all the way inside. Here's what happened to mine:

The first time I changed the hydraulic and HST filters on my M59 they were very difficult to get off. I finally did get them undone, but had to fabricate a special strap band wrench with a long cheating handle. I've since read on TBN that other folks have had the same problem - particularly when replacing the original factory filters for the first time. Mine finally did came off cleanly. But I was sure surprised at how tight they were.

Then when I got to looking at how the filters were mounted, they simply screw onto what looks to be a standard 3 or 4" regular old plumbering pipe nipple that has one end threaded into the transmission housing and the filter threads onto the other end. And here's the kicker, that pipe nipple part was loose in my tractor. Both the HST and the Hydraulic nipples were loose in the transmission housing. I could wiggle them with my finger and unscrew them by hand! Apparently either they had gotten stuck in the filters and unscrewed with it, or were never tightened at the factory.....or maybe both. There were marks on the pipe nipple like someone had tried to tighten it at the factory or dealership, but it didn't work because you can't really get to the part with a pipe wrench. It requires an internal cam lock wrench - which is common enough for plumbers, but not a tool found in most mechanical tool kits.

Now I wonder if that that loose nipple could cause an air leak? I don't know the answer for sure...but suppose that it could. Whether or not it does kinda depends on how that transmission casting is made and how it is vented inside.

What I did to mine was to unscrew both nipples, cleaned the threads into the housing, and then put the nipples back into the transmission housing using an internal cam-lock pipe wrench along with Loctite. Now they stay put and there is no way that they could leak air even if that were possible.
So far no more problems, but I do check those pipe nipples each time I have the filters off.
rScotty

 

[woody]

Thanks rScotty I keep that in mind.

 

[woody]

okay I didn't think I would have time to work on the B26 until next week but I pulled the rubber elbow off the pump today and cleaned it up blew it out with air put the shop vac on it and covered the other end, I mashed it and pulled on it but never did find a crack or hole so next time i'll try something else.

 

[100 td]

Did you also pull the suction pipe and check the oring? Do you have an IR thermometer? If so put it on your pump when you start engine and see if there is excessive temperature rise in either pump.
Whilst checking your nipples is always a good thing, the nipple is simply "inside" the hydraulic circuit and if oil bypassed down the minute cavities in the threads, that tiny bit of oil is just bypassing the filter. If air was to bypass, then there is no oil there, so you have a major problem as there is no oil in the tank getting to the nipple. If the nipple was cross threaded in the filter housing, it may stop the filter from screwing on far enough to allow the gasket to properly seal.

 

[woody]

Did you also pull the suction pipe and check the oring? Do you have an IR thermometer? If so put it on your pump when you start engine and see if there is excessive temperature rise in either pump.
Whilst checking your nipples is always a good thing, the nipple is simply "inside" the hydraulic circuit and if oil bypassed down the minute cavities in the threads, that tiny bit of oil is just bypassing the filter. If air was to bypass, then there is no oil there, so you have a major problem as there is no oil in the tank getting to the nipple. If the nipple was cross threaded in the filter housing, it may stop the filter from screwing on far enough to allow the gasket to properly seal.

Thanks, when I get back I am going to drain the fluid and replace both o-rings, check nipples while I have it torn down. I did notice yesterday that after the oil and air stopped coming out of the vent I heard a loud bubble sound inside the tank and the oil level dropped when the air escaped the fluid it has blown enough oil out now that the level does not even touch the stick after I let it sit for awhile.

 

[rScotty]

Thanks, when I get back I am going to drain the fluid and replace both o-rings, check nipples while I have it torn down. I did notice yesterday that after the oil and air stopped coming out of the vent I heard a loud bubble sound inside the tank and the oil level dropped when the air escaped the fluid it has blown enough oil out now that the level does not even touch the stick after I let it sit for awhile.

I think those places are both worth the time and expense to check. I would do that on my own machine.
It makes sense that the oil level needs to keep above a certain level to protect the sliding surfaces on pump and HST. Again, if it was my machine I'd keep adding oil even if it did get blown out.

That vent tube should be pretty clean by now. I don't know what is available, but there are such things as air/oil seperators that could be affixed to the vent tube until you find the problem. A separator is basically a small reservoir filled with SS screen and has a vent on top to let the air out. It slows the oil down & cools it so the air can escape. Not 100% efficient while running.

I looked at the workshop manual for our M59, but cannot tell if the filter-mounting nipples are above or below the normal fluid level in the transmission reservoir. As near as I can tell by the illustration I believe that If the upper nipple threads in the block were real loose....AND those threads were above the normal oil level in the reservoir ... then that combo could cause an air leak into the fluid. The B26 may be different.
rScotty