Hydraulic fluid from trans vent

[bsamot69]

Our m9000, can, front loader, 2 wheel drive has hydraulic fluid coming out of trans vent. I have posted about this previously and followed the recommendation. Initially, when operating tractor hydraulic fluid poured out vent. The fluid was saturated with air bubbles. What has been done? The two piece suction tube was removed. The hydraulic pump was removed so the manifold on bottom could be removed to replace the o rings. All the orings, top and bottom have been replaced on pump. The orings on both ends and middle of suction tube have been replaced. Both hydraulic filters are new and no double gasket problem. The fluid is new and proper level. Start the tractor and within minutes the fluid is leaking from vent complete with bubbles. The tractor functions normally. Steering works, front loader works, 3 point hitch, all function normal. So, if it goes to shop, what will they be looking at? What is next to check. It makes sense air being sucked into system but have replaced all the orings but obviously there must be something I missed. What would you all check next? Baffle, challenged, frustrated and not giving up, I am

 

[je1279]

Our m9000, can, front loader, 2 wheel drive has hydraulic fluid coming out of trans vent. I have posted about this previously and followed the recommendation. Initially, when operating tractor hydraulic fluid poured out vent. The fluid was saturated with air bubbles. What has been done? The two piece suction tube was removed. The hydraulic pump was removed so the manifold on bottom could be removed to replace the o rings. All the orings, top and bottom have been replaced on pump. The orings on both ends and middle of suction tube have been replaced. Both hydraulic filters are new and no double gasket problem. The fluid is new and proper level. Start the tractor and within minutes the fluid is leaking from vent complete with bubbles. The tractor functions normally. Steering works, front loader works, 3 point hitch, all function normal. So, if it goes to shop, what will they be looking at? What is next to check. It makes sense air being sucked into system but have replaced all the orings but obviously there must be something I missed. What would you all check next? Baffle, challenged, frustrated and not giving up, I am

Sounds like it's still sucking air in from somewhere. Try smoke testing all of the connection points and see if you can find which one is drawing smoke in.

 

[GreensvilleJay]

possible test ..
let sit overnight(hopefully to get rid of bubbles...)
start it up but do NOT touch ANY levers !
run 'long enough' and look at the oil in vent.
if NO bubbles, then not an 'internal' problem
operate ONE lever, 'long enough', check for bubbles
if bubbles THAT is where they're coming from
none ? ,check next lever...
I suspect either a 'loose' fitting or a 'weepy' hose. It doesn't take much to allow air in and oil won't flow out....

 

[xrocketengineer]

No tractor expert here but is it possible to to apply some low air pressure ( just a few psi) into the transmission and check for leaks with a soapy water solution and look for bubbles on whatever external joints that might be in question? Kind of the smoke test in reverse.

 

[Silver Wings]

I'm not familar with your M9000, but on my little B21 I had the same issue...fluid from the vent, small amount of engine oil in the hydraulic fluid and also a loss of prime to the hydraulic pump after sitting in cold weather. After doing just about everything you did the problem persisted, then I changed the shaft seal on the pump. This solved the fluid from the vent, but it would still lose prime in very cold weather. I believe the partial fix was due to the shaft being a little worn, thus not a perfect seal. It's also had a lack of performance as far as the hydraulics were concerned...I estimated 30% loss, give or take. Today I put a new pump on and changed fluid and filters. It's like having a new tractor. I'd forgotten how strong the little B21 used to be. The shaft seal was $8...it's worth a try.

 

[kubotafreak]

I'm not familar with your M9000, but on my little B21 I had the same issue...fluid from the vent, small amount of engine oil in the hydraulic fluid and also a loss of prime to the hydraulic pump after sitting in cold weather. After doing just about everything you did the problem persisted, then I changed the shaft seal on the pump. This solved the fluid from the vent, but it would still lose prime in very cold weather. I believe the partial fix was due to the shaft being a little worn, thus not a perfect seal. It's also had a lack of performance as far as the hydraulics were concerned...I estimated 30% loss, give or take. Today I put a new pump on and changed fluid and filters. It's like having a new tractor. I'd forgotten how strong the little B21 used to be. The shaft seal was $8...it's worth a try.

How many hours did you have on the B21?

 

[Silver Wings]

How many hours did you have on the B21?

I'm not sure because the hour meter broke about 10 years ago, but my guesstimate would be in 2200 range.

 

[SidecarFlip]

I wouldn't be applying pressure to the gearcase. The case is designed to run at atmospheric pressure and pressurizing it can blow seals out. You are sucking air somewhere. I'd bet a compromised supply line to the pump.

A trip to the dealer might be the next avenue.

 

[GeoHorn]

I don’t think pressurizing the case is a good idea either. The reason for a “vent” is to prevent any pressure from building.

 

[Reddogfarm]

I'm not sure because the hour meter broke about 10 years ago, but my guesstimate would be in 2200 range.

Thanks for your details here and glad the repair worked out.

I have a new to me B20 also with a broken hour meter that is leaking hydraulic fluid at the vent under the seat. The vent leak only seems to occur as the tractor is sitting and warming up in the first ten minutes or so. It pukes a fair amount and then settles out and stops leaking. I can’t seem to keep fluid showing on the dip stick, when checked hot or cold, as if I top off the fluid so it just shows on the dip stick it just leaks out the vent and drops below the dipstick again. Sometimes the fluid looks extremely aerated and almost milky after it leaks out too, but when you wipe it still looks clean.

I serviced all the fluids and filters when I bought the tractor this fall, including changing the hydraulic filters and fluid. I do have two cylinders with small leaks, one loader and one bh stabilizer.

Does this sound like the same issue that you resolved with changing the pump?

 

[Silver Wings]

Thanks for your details here and glad the repair worked out.

I have a new to me B20 also with a broken hour meter that is leaking hydraulic fluid at the vent under the seat. The vent leak only seems to occur as the tractor is sitting and warming up in the first ten minutes or so. It pukes a fair amount and then settles out and stops leaking. I can’t seem to keep fluid showing on the dip stick, when checked hot or cold, as if I top off the fluid so it just shows on the dip stick it just leaks out the vent and drops below the dipstick again. Sometimes the fluid looks extremely aerated and almost milky after it leaks out too, but when you wipe it still looks clean.

I serviced all the fluids and filters when I bought the tractor this fall, including changing the hydraulic filters and fluid. I do have two cylinders with small leaks, one loader and one bh stabilizer.

Does this sound like the same issue that you resolved with changing the pump?

I'll preface my response by saying...I'm no expert, but I have dealt with this issue and received help right here on this forum. So I'll pass along what I learned in hopes it helps.
To answer your question, it does sound like my issue. With that said...installing a new pump at $600 parts only should be a last resort. I believe you're sucking air from somewhere on the intake side of the pump. So that could be at any point from the pick up tube (O rings) at the hydraulic reservoir to the pump, or the pump shaft seal or a combination of any of those. The good news is those parts are cheap and worth changing to see if that stops the air leak. I had no outward signs of any hydraulic leak...as in damp hose, ect... The two main symptoms were puking of fluid from the vent during cold start and loss of prime at hydraulic pump in cold weather after sitting for 24 hours or more. I also had a loss of capacity in terms of hydraulic performance...after having the tractor for 12 years I knew what it could do. You probably don't have the benefit of knowing what yours should do since it's new to you. Changing the S shaped rubber hose on the suction side of the pump is a breeze (I'm assuming yours is the same). Changing the shaft seal is a little more involved but still a fairly easy job. Let me know if you have more questions.

 

[bsamot69]

Here is the update on the m9000:. I used a smoke machine on the transmission case starting at the rear. That is how I discovered the other vents. The one on top of case in the back, the one mid tractor right side...I temporarily caped off these points and introduced smoke at each vent. I did not see any smoke from anywhere on tractor. I have done this a few times just to be sure. From reading the replies above, the pump seal is the next step. Would that apply to my situation? The hydraulic system on our tractor has the pump attached to an assembly in front of pump that runs up to power steering. The top of pump has assembly on top with lines to other components. The pump bottom has suction manifold connecting front assembly to manifold to the pipe that runs to the back. I describe all that because I saw 3 different configurations for our machine. Does replacing the seal on pump require disassembly of the pump? Or am I fortunate to just install seal with no disassembly?

 

[ruger1980]

Did you perform the smoke test with the sump empty or with oil in the sump? If full of oil the smoke would not be able to reach the feed line to the pump. Also it is possible that the smoke may not show as during operation the suction line is under a negative pressure and some leaks do not show unless there is a negative pressure.

 

[je1279]

Here's a video I found of a disassembled hydraulic pump from an L series that may or may not be helpful.