NX6010 suction side hydro leak

[xcgreene]

Any updates on this from others seeing the problem? I'm a little reluctant to say this, but now, about 100 hrs after the filter housing was replaced, I'm afraid the issue might be coming back. I heard it "burp" on air a few times the other day out using it. Hydraulics are behaving well, but I still have the clear section in my suction line and.. Yup.. I see bubbles. We'll see what happens, if it fails again, at least I know what the problem is and can just go right there, but, why on earth would this be "coming back"?

Actually, that's an interesting question in general. Because this issue clearly got worse as time passed, and yet, it was equally clear that replacing the filter housing fixed it. So something in that housing is "wearing out". But I've had it in my hand, it's a chunk of steel with a few holes in it. What on earth is "failing" in these things? Yes, I get it, bad castings, lots of heat, maybe the expansion/contraction breaks it over time? But this is just so strange. Maybe it's eroding through time because the passages aren't "smooth enough"? IDK, just grasping at straws here. But it feels like this is kind of like "wearing out" the block of an engine. They don't wear out, they wear away. And if you're "wearing out" an engine block in 1000 miles, well.. Something ain't right.

I'd say your right about the bad casting. A spot in the casting that is destined to crack over time, the crack becoming longer and longer. A proper NDT on a few of the failed housing would tell us a lot. If anyone who has changed theirs out for new, and still has their old housing, it would be interesting to take it to a machine shop and have it checked. Or one could go the cheap route and buy a couple cans of the NDT paint.

 

[xcgreene]

Wanted to Bump this thread again. Any more news?

 

[justman777]

Nope....nothing from my end. I'm still not sure what's going on, but I think it'd be interesting to try gather some info from folks to make an informed hypothesis. For instance...

- For those of us with issues, does it make noise all the time or just when the fluid is cold (or hot)?
- Has anyone tried a lower viscosity hydro fluid, like 20 weight vs the specified 30 weight?
- For those without issues, what brand/viscosity fluid do you use?
- Has anyone ripped the guts out of a filter and tried it with just the can? Not likely, I know...
- Are you using the Kioti filter or an aftermarket one?

What I suspect is happening is cavitation in the suction side due to a restriction in the hydro fluid flow, and that's causing the bubbles and odd noises. I think the only way to really see what's going on is to see how much vacuum is being created on the suction side and see if that falls within specs for the hydraulic system. Alternatively, there may be a way to bypass the filter head assembly (for testing purposes only) to determine if the filter and filter head are creating a restriction in the fluid flow, and thus causing cavitation immediately after the filter head assembly.

I know there's a debate between cavitation and aeration on this issue, but I've looked all over the old filter head and just can't see how it's leaking air and causing aeration. It's a chunk of metal with a hole that goes in and a hole that goes out. If someone were to bypass the filter assembly with clear tubing (briefly), I think that'd be telling.

 

[YLee Kioti]

So I used NAPA Coastal synthetic fluid and topped off with two gallons of Kubota non-synthetic fluid.
I have noticed that when traveling in reverse it is jerky. A steady pedal of easy pressure to travel slow and it will jerk in reverse, not in forward.
Also, the 3PH will drop and then the cutter will jump/hop.
It's near triple digits here and still ahve to drive until it fully warms up and the reverse issue is reduced but the 3PH is the same.
It has 375 hours on the clock and plan on taking it in for its 400 hour valve lash check, since its in warranty.
Plan on sharing all this with dealer and see what he has to offer. For now though too many projects to have out of commission. Have an elderly veteran with 10 acres that need shredding.

Are these issues related to yours about aeration or cavitation, don't know. Mine does not make any unusual noise to speak of.
If this thread is still alive in the the fall will come came with update of what dealer has to offer.
Thanks for keeping us posted.

 

[justman777]

Hello to all, new here to the forum. Add me to this list also. NX4510 HST 2018 with 90 hours on it. I have bubbles as i look into the rear fill port. I changed hydraulic fluid (purchased from dealer) at 50 hours. I changed both hydraulic filters also. I recheck to make sure the filters are tight several times.
The sound is the same as justman777's video. justman777 did your dealer give you the part as a warranty claim?
Thanks

Treefarmer, I had the dealer send me the part as a warranty claim. However, it didn't fix the issue. I'm still getting the noise and bubbles in the sump.

This has me stumped. I'm thinking cavitation, but I'm not a hydraulic engineer. I'm just a somewhat mechanically inclined person of average intelligence. So...I did the same thing I always do when something is broke and I don't know how to fix it. I go to YouTube! :laughing:

I found the video here that may help us all out: All About Hydraulic Cavitation - Wrenchin' Up - YouTube

I discerned a few things from the video. First----the hydraulic system should NOT have ANY air in it. Like at all. Any air is very, very bad for your hydraulic system. Second----there's a few more possibilities to consider other than cavitation. The guy giving the demo shows cavitation, pseudo-cavitation, and turbulence.

Watching this video got me to thinking....is it cavitation, or is it pseudo-caviatation? Or, is the return line sitting above the oil level and it's causing turbulence, which in turn is causing air to be put into the fluid? From the video, it looks more like pseudo-cavitation than actual cavitation, because in true cavitation, the bubbles would collapse in the pump and you wouldn't have any air being put back into the sump. Psuedo-cavitation (what we're calling an air leak), however, causes air bubbles to go all the way through the hydraulic system and wind up in the sump. Turbulence caused by the return line being above the level of the sump fluid could also be the cause of air getting into the system.

I obviously can't test for pseudo-cavitation, but I wonder if over-filling the sump would bring the oil level up enough to test for turbulence.

Thoughts, anyone?

 

[justman777]

So I used NAPA Coastal synthetic fluid and topped off with two gallons of Kubota non-synthetic fluid.
I have noticed that when traveling in reverse it is jerky. A steady pedal of easy pressure to travel slow and it will jerk in reverse, not in forward.
Also, the 3PH will drop and then the cutter will jump/hop.
It's near triple digits here and still ahve to drive until it fully warms up and the reverse issue is reduced but the 3PH is the same.
It has 375 hours on the clock and plan on taking it in for its 400 hour valve lash check, since its in warranty.
Plan on sharing all this with dealer and see what he has to offer. For now though too many projects to have out of commission. Have an elderly veteran with 10 acres that need shredding.

Are these issues related to yours about aeration or cavitation, don't know. Mine does not make any unusual noise to speak of.
If this thread is still alive in the the fall will come came with update of what dealer has to offer.
Thanks for keeping us posted.

From what you describe, I'm not sure the issues you're having are related. Could be... You may try re-calibrating your pedals (have to do both at the same time, if I recall correctly), and getting your dealer to check out your MLS valve. My three point is very smooth. The only thing I get is the odd noise and bubbles in the sump.

 

[YLee Kioti]

From what you describe, I'm not sure the issues you're having are related. Could be... You may try re-calibrating your pedals (have to do both at the same time, if I recall correctly), and getting your dealer to check out your MLS valve. My three point is very smooth. The only thing I get is the odd noise and bubbles in the sump.

Thanks for the info will share with dealer. :thumbsup: :drink:

 

[justman777]

Made another video in an attempt to show the bubbles in the hydro sump.

Kioti NX451 Air in hydraulic fluid - YouTube

I apologize for the audio. Took it using my phone, and of course, I'm in close proximity to the tractor. :laughing:

Can someone verify the "wind tunnel" noise I referenced in the video is the same on their tractor? Also, how about the bubbles...is this normal?

Thanks!

 

[justman777]

Anyone?

 

[YLee Kioti]

Well I did listen closely and a embarrassed to say that I did not hear anything abi-normal.
Maybe I got so used to the noises that I considered them all normal.
I will check with a flashlight to see if there are any bubbles.
Wish I could've been more help.