Kubota bucket leaks

[tennman0258]

Seems Kubota has a problem with bucket dump leak downs just as my Kubota LA844 .
Also , have you noticed that the bucket doesn't have the power or strength when you roll/curl it back ? Mine is very weak on roll back and should be it's strongest thing/point on the loader .
All this is on a 2012 MX700 tractor with only 220 hours . Shame !
Any fixes for this crap ?
I've repacked the left cylinder and it didn't even need it when I took it apart . Haven't done the right cylinder...yet...as the seal kit is around80-90 bucks for a few rubber O-Rings and a couple seals , which is ridiculous too !
After re-packing one cylinder , I took the valve body apart only to find nothing wrong with any o-rings and split plastic things too . I did replace them by the way . Another 40 bucks shot to hell .
No pressure test have been done yet . Also no leaks anywhere .
I'm a mechanic by trade fyi . So hit me up with some knowledge guys !
Any suggestions appreciated .

 

[GeoHorn]

A hydraulic cylinder will have higher capability in one direction than the other by design. The piston is attached to the rod and on the rod-side (where yours likely “curls back” has less surface area exposed to the hydraulic fluid pressure than the side which does not have the rod.... therefore will have less capability on the rod-side of the piston.

 

[tennman0258]

A hydraulic cylinder will have higher capability in one direction than the other by design. The piston is attached to the rod and on the rod-side (where yours likely “curls back” has less surface area exposed to the hydraulic fluid pressure than the side which does not have the rod.... therefore will have less capability on the rod-side of the piston.

Normally all buckets will have more curl pressure than even the lift itself . This one doesn't . If the tractor was ever stuck , let's say , you would use the curl bucket to help ease yourself out . Don't think this system/curl would even do that . It just squalls with a load on the bucket .
Thanks for the reply .

 

[Dave_eng]

I will start by saying, so as not to seem critical of your efforts: Hydraulic knowledge is difficult to obtain

Jumping in a repacking cylinders without any tests...................

Taking apart a loader control valve before any formal tests........

Step one in my world would have been to swap the bucket and loader arm hoses to see if the "problem" moved. A test with no costs.

If the bucket still performed poorly under the control of a different valve spool, then you now know the loader valve is OK.

The simple cylinder test I will attach below can be done and the only cost is a couple of caps and plugs. This test will identify cylinders which are swelled in the middle or leaking internally. Conditions not visible to the naked eye.

If you think any of the above will help you, try them and report back. Kubota owners are rarely unhappy with their equipment. Some acknowledge having asked more of it than it was designed to provide.

Dave

 

[kubotafreak]

I think without the loader relief pressure, we are all guessing.

 

[tennman0258]

I will start by saying, so as not to seem critical of your efforts: Hydraulic knowledge is difficult to obtain

Jumping in a repacking cylinders without any tests...................

Taking apart a loader control valve before any formal tests........

Step one in my world would have been to swap the bucket and loader arm hoses to see if the "problem" moved. A test with no costs.

If the bucket still performed poorly under the control of a different valve spool, then you now know the loader valve is OK.

The simple cylinder test I will attach below can be done and the only cost is a couple of caps and plugs. This test will identify cylinders which are swelled in the middle or leaking internally. Conditions not visible to the naked eye.

If you think any of the above will help you, try them and report back. Kubota owners are rarely unhappy with their equipment. Some acknowledge having asked more of it than it was designed to provide.

Dave

What you wrote seems legit and will try these test very soon . Ty kind sir for the attached file too .
I could have a swelled cylinder for sure as all of this start when a buddy of mine was bushogging and had forks on the loader and didn't know they were so close to the ground and soon he found out as they dug in the ground and it busted a steel line that goes to the bucket before he could get stopped . . Hard to believe it busted a metal line like it did . It didn't use to leak down before this happened and I've been frustrated over it ever since .
Question , If i tore down the only other cylinder ,that I didn't repack, and the found a swelled cylinder , wouldn't blow the packing/seals and I could see them visually ?
Both cylinder arms look (by the naked eye) very straight when I curl the bucket wide open .
Thanks again . Hopefully your test will find me a fix.

 

[kubotafreak]

What you wrote seems legit and will try these test very soon . Ty kind sir for the attached file too .
I could have a swelled cylinder for sure as all of this start when a buddy of mine was bushogging and had forks on the loader and didn't know they were so close to the ground and soon he found out as they dug in the ground and it busted a steel line that goes to the bucket before he could get stopped . . Hard to believe it busted a metal line like it did . It didn't use to leak down before this happened and I've been frustrated over it ever since .
Question , If i tore down the only other cylinder ,that I didn't repack, and the found a swelled cylinder , wouldn't blow the packing/seals and I could see them visually ?
Both cylinder arms look (by the naked eye) very straight when I curl the bucket wide open .
Thanks again . Hopefully your test will find me a fix.

Could take some calipers to the loader cylinder tubes to put this theory to proof.

 

[imnukensc]

Rule #1) Don't let "buddies" borrow or use your tractor.

Rule #2) See Rule #1

 

[GreensvilleJay]

could be a 'Murphy thing'... you repacked the GOOD cylinder....it's the OTHER one that's bad....
since cylinders are in parallel, all oil will 'backflow' though the bad seal.

 

[Dave_eng]

I was going to ask if forks had a part in your tractor's history but did not want to throw gasoline on the emotional fire.

Some of the hydraulic knowledge I told you is hard to obtain has to do with pressure relief valves in loader hydraulic systems.

Take the time to watch this short video below. It will reinforce what I am about to tell you.

When you try and lift something with your loader, a pressure relief valve limits how much pressure can be directed to the cylinders. This is done to save the cylinders, lines and hoses from being over pressured. This relief valve is only connected into the circuit when the joystick is directing flow to a cylinder. The moment the joystick returns to the neutral position, the relief valve is gone and the hydraulic fluid is locked into a circuit until something breaks.

A simple way to overload your loader hydraulics is to lift a bucket of gravel whose weight is just at the loader's limit. Now get off the tractor and continue to shovel material into the bucket. Common sense tells you the hydraulic pressure in the cylinders has to increase to support the additional load you shoveled into the bucket

If you shovel in enough material, eventually something will break.

The linkage between your bucket cylinders and the bucket which permits you to roll the bucket back until it is like a trough in order to retain material), acts like a long pipe on a socket wrench power bar under certain bucket positions.

Your owner's manual for your loader will caution against tipping the bucket forward and bulldozing material. Why? The bucket tipped far forward is magnifying forces sent back into the bucket hydraulics and there is no relief valve to protect the hydraulics.

Messicks Grapple amplification

Forks, used by members on this forum have broken many hydraulic cylinders. The split steel line is evidence just how high the hydraulic pressures in your system spiked when the forks touch the ground while the tractor was moving forward.

Dave

 

[tennman0258]

I was going to ask if forks had a part in your tractor's history but did not want to throw gasoline on the emotional fire.

Some of the hydraulic knowledge I told you is hard to obtain has to do with pressure relief valves in loader hydraulic systems.

Take the time to watch this short video below. It will reinforce what I am about to tell you.

When you try and lift something with your loader, a pressure relief valve limits how much pressure can be directed to the cylinders. This is done to save the cylinders, lines and hoses from being over pressured. This relief valve is only connected into the circuit when the joystick is directing flow to a cylinder. The moment the joystick returns to the neutral position, the relief valve is gone and the hydraulic fluid is locked into a circuit until something breaks.

A simple way to overload your loader hydraulics is to lift a bucket of gravel whose weight is just at the loader's limit. Now get off the tractor and continue to shovel material into the bucket. Common sense tells you the hydraulic pressure in the cylinders has to increase to support the additional load you shoveled into the bucket

If you shovel in enough material, eventually something will break.

The linkage between your bucket cylinders and the bucket which permits you to roll the bucket back until it is like a trough in order to retain material), acts like a long pipe on a socket wrench power bar under certain bucket positions.

Your owner's manual for your loader will caution against tipping the bucket forward and bulldozing material. Why? The bucket tipped far forward is magnifying forces sent back into the bucket hydraulics and there is no relief valve to protect the hydraulics.

View attachment 60117



Messicks Grapple amplification

Forks, used by members on this forum have broken many hydraulic cylinders. The split steel line is evidence just how high the hydraulic pressures in your system spiked when the forks touch the ground while the tractor was moving forward.

Dave

Thank you sir for that explanation and video !

 

[D2Cat]

Here's one of the comments posted on that video. Describes your friends destruction of your equipment.




Brian G C
11 months ago

While driving forward slowly, using a rock bucket to screen out large rocks in a freshly cut driveway, I hit a hidden 24" round boulder and the front of my tractor lifted up too quickly for me to react and I burst a 12mm steel hydraulic line. When I tried to buy a compression fitting to mend the line, I found out the entire 30" line had swollen more than a mm oversized. I had a hydraulic tube shop fabricate and repair it for me. Fortunately it only cost $65 and none of my valves were damaged. Those cylinders can easily created pressures that will destroy your hydraulic system quicker than you can blink an eye.

 

[tennman0258]

Here's one of the comments posted on that video. Describes your friends destruction of your equipment.




Brian G C
11 months ago

While driving forward slowly, using a rock bucket to screen out large rocks in a freshly cut driveway, I hit a hidden 24" round boulder and the front of my tractor lifted up too quickly for me to react and I burst a 12mm steel hydraulic line. When I tried to buy a compression fitting to mend the line, I found out the entire 30" line had swollen more than a mm oversized. I had a hydraulic tube shop fabricate and repair it for me. Fortunately it only cost $65 and none of my valves were damaged. Those cylinders can easily created pressures that will destroy your hydraulic system quicker than you can blink an eye.

We're not friends no more ! lol Just kidding ....he was bushogging and I should have taken the forks off ....but ...I was at work and I told him to just go get it and do what he needed to do . It was an honest mistake . I'm just the one paying for it . FYI, I bought a new line too....125 dollars shipped to me from FL to Tn.