M6950 hydraulic issue

[1fishinrogers]

I could really use some professional advice. After using the tractor for 15 to 20 minutes the hydraulics will slowly fail. I have guaged the the pressure and and upon cranking cold pressure is zero but once you move any lever the pressure increases to approximately 1000psi and once satisfied only drops to 800 and remains there until the pump overheats and pressure drops to almost nothing but it's not in bypass just not pumping. I have adjusted lift arms and control lever to specs but didn't help. Any help will be appreciated. Thanks

 

[TheOldHokie]

I could really use some professional advice. After using the tractor for 15 to 20 minutes the hydraulics will slowly fail. I have guaged the the pressure and and upon cranking cold pressure is zero but once you move any lever the pressure increases to approximately 1000psi and once satisfied only drops to 800 and remains there until the pump overheats and pressure drops to almost nothing but it's not in bypass just not pumping. I have adjusted lift arms and control lever to specs but didn't help. Any help will be appreciated. Thanks

I think you need to get a better understanding of how pressure testing works.

Where and how have you connected the gauge?

Dan

 

[1fishinrogers]

I think you need to get a better understanding of how pressure testing works.

Where and how have you connected the gauge?

Dan

Well Dan I think I have a pretty good idea of how to test pressure and with the guage connected to the pressure side of the pump and listening to the tractor pull down because of a constant load even though there isn't a load not to mention failure of the system after 15 minutes I'm pretty sure what I'm dealing with is a seal damaged and letting enough fluid escape that the bypass is staying partially open or something is deadheading the fluid but what I do know is that I am looking for someone that has experienced this and repaired it not someone to criticize my ability or inability to trouble shoot

 

[TheOldHokie]

Well Dan I think I have a pretty good idea of how to test pressure and with the guage connected to the pressure side of the pump and listening to the tractor pull down because of a constant load even though there isn't a load not to mention failure of the system after 15 minutes I'm pretty sure what I'm dealing with is a seal damaged and letting enough fluid escape that the bypass is staying partially open or something is deadheading the fluid but what I do know is that I am looking for someone that has experienced this and repaired it not someone to criticize my ability or inability to trouble shoot

I was goung to provide that help but apparently you have it all figured out.

Good luck.

Dan

 

[1fishinrogers]

I was goung to provide that help but apparently you have it all figured out.

Good luck.

Dan

Maybe you can Maybe not but either way I don't need or want sarcasm. I'm sure there are others that have the answer and luck will not be a factor.

 

[RCW]

Maybe you can Maybe not but either way I don't need or want sarcasm. I'm sure there are others that have the answer and luck will not be a factor.

Well, my friend @TheOldHokie is probably one of the most savvy hydraulics guys around.

He helps countless people here on OTT EVERYDAY to fix their hydraulic problems. He’s very thorough and knowledgeable.

You’re obviously a lot smarter than he is and tossed his offer to help aside.

Good luck.

 

[1fishinrogers]

Well, my friend @TheOldHokie is probably one of the most savvy hydraulics guys around.

He helps countless people here on OTT EVERYDAY to fix their hydraulic problems. He’s very thorough and knowledgeable.

You’re obviously a lot smarter than he is and tossed his offer to help aside.

Good luck.

Perhaps but regardless I posted here looking for answers not ridicule. If I had all the answers I wouldn't have wasted my time asking for those answers on this site. Eventually the information I need will come, thanks.

 

[TheOldHokie]

Perhaps but regardless I posted here looking for answers not ridicule. If I had all the answers I wouldn't have wasted my time asking for those answers on this site. Eventually the information I need will come, thanks.

Look, there was no ridicule intended. My apologies if you took it that way.

Answer my question and you might get something helpful in return.

Dan

 

[North Idaho Wolfman]

Perhaps but regardless I posted here looking for answers not ridicule. If I had all the answers I wouldn't have wasted my time asking for those answers on this site. Eventually the information I need will come, thanks.

I'll say this, on your second post you jump all over the person that trying to help you out?
Not what I would call exactly a smart move.

Kubota hydraulic systems like yours are an open system.
If your getting pressure with the system in neutral your dead heading / or putting the system up against the relief valve, so yes you have a problem.

FYI: Yea @TheOldHokie is one of the most knowledgeable people on here when it come to hydraulic systems, so apologizing to him and move on will get you a lot further than my advice of get the WSM and follow what it says.

 

[1fishinrogers]

Look, there was no ridicule intended. My apologies if you took it that way.

Answer my question and you might get something helpful in return.

Dan

The guage is in the pressure line directly off the pump, cold start pressure is zero touch any lever lift or spool it doesn't matter the pressure goes to a 1000 and when the lift satisfies it drops to 800 and remains until the pump obviously overheats and slowly loses pressure and and will only function after the engine is stopped and sits for a minute restart and it does the same thing but the lift arms also fall as soon as the engine is stopped thus the bypass I just don't know exactly where to look because the valve just under the cover which appears to be the bypass is dumping a reasonable amount of fluid plus I can't find any info on that valve

 

[North Idaho Wolfman]

The guage is in the pressure line directly off the pump, cold start pressure is zero touch any lever lift or spool it doesn't matter the pressure goes to a 1000 and when the lift satisfies it drops to 800 and remains until the pump obviously overheats and slowly loses pressure and and will only function after the engine is stopped and sits for a minute restart and it does the same thing but the lift arms also fall as soon as the engine is stopped thus the bypass I just don't know exactly where to look because the valve just under the cover which appears to be the bypass is dumping a reasonable amount of fluid plus I can't find any info on that valve

Excellent, the three point information should be helpful.

 

[Shadetree605]

Well Dan I think I have a pretty good idea of how to test pressure and with the guage connected to the pressure side of the pump and listening to the tractor pull down because of a constant load even though there isn't a load not to mention failure of the system after 15 minutes I'm pretty sure what I'm dealing with is a seal damaged and letting enough fluid escape that the bypass is staying partially open or something is deadheading the fluid but what I do know is that I am looking for someone that has experienced this and repaired it not someone to criticize my ability or inability to trouble shoot

man, i sure as heck hope you don't take this post the wrong way either ??..lol. i normally don't ask for help on here, but i can tell you this !..i've read a crap load of dan's post, and he Seem's to be the smartest person i know of on here when it comes to issues like this. i know this ?..if and when i need help with my tractor for hydraulics ?..dan will be the very first person i ask for help !..lol. i'm sure he did not mean to sound, or come off sounding like a jerk ?, sooo..you may want to listen to this man, he's a very smart man when it comes to this. good luck.

 

[TheOldHokie]

The guage is in the pressure line directly off the pump, cold start pressure is zero touch any lever lift or spool it doesn't matter the pressure goes to a 1000 and when the lift satisfies it drops to 800 and remains until the pump obviously overheats and slowly loses pressure and and will only function after the engine is stopped and sits for a minute restart and it does the same thing but the lift arms also fall as soon as the engine is stopped thus the bypass I just don't know exactly where to look because the valve just under the cover which appears to be the bypass is dumping a reasonable amount of fluid plus I can't find any info on that valve

Lets try to take things slower snd in smaller bites so I can get a better understanding of whats happening. Please humor me and provide simple direct answers to my questions - I am a slow learner.

It sounds like you have one or possibly two rear remote valves in addition to the three point lift on that tractor. Is that correct? If so anything connected to the remote valves?

Is the gauge installed in the pump discharge line with a tee? A picture of the gauge hookup would be helpful.

If the gauge is teed into the pump discharge line zero pressure at startup is normal behavior. The pump is simply recirculating to tank.

When you operate a lever pressure increases because you have blocked oil flow to tank and diverted oil to an actuator. When you return the lever to neutral the path to tank should be restored and pressure should return to zero. You say that does not happen. Correct?

Dan

 

[BAP]

1fishingrogers, everyone else is rushing in to tell how have or haven’t tested properly but nobody has bothered to ask you or give you some bad advice. First, have you changed your filters recently? Second, if your tractor has a suction screen for the hydraulic pump have you cleaned that? Third, is your fluid level at the proper level and is it the correct oil type. Sometimes people get so quick to jump on doing all kinds of testing that they overthink and overlook some of the most basic things that can be the cause of the problems. If your suction screen is plugged you aren’t going to get enough flow to make pressure and cause damage to the pump. Seen it happen many times before.

 

[TheOldHokie]

1fishingrogers, everyone else is rushing in to tell how have or haven’t tested properly but nobody has bothered to ask you or give you some bad advice. First, have you changed your filters recently? Second, if your tractor has a suction screen for the hydraulic pump have you cleaned that? Third, is your fluid level at the proper level and is it the correct oil type. Sometimes people get so quick to jump on doing all kinds of testing that they overthink and overlook some of the most basic things that can be the cause of the problems. If your suction screen is plugged you aren’t going to get enough flow to make pressure and cause damage to the pump. Seen it happen many times before.

Disconnect one side of that gauge and start the engine. He will know real fast if there is an oil supply....

Dan

 

[1fishinrogers]

Lets try to take things slower snd in smaller bites so I can get a better understanding of whats happening. Please humor me and provide simple direct answers to my questions - I am a slow learner.

It sounds like you have one or possibly two rear remote valves in addition to the three point lift on that tractor. Is that correct? If so anything connected to the remote valves?

Is the gauge installed in the pump discharge line with a tee? A picture of the gauge hookup would be helpful.

If the gauge is teed into the pump discharge line zero pressure at startup is normal behavior. The pump is simply recirculating to tank.

When you operate a lever pressure increases because you have blocked oil flow to tank and diverted oil to an actuator. When you return the lever to neutral the path to tank should be restored and pressure should return to zero. You say that does not happen. Correct?

Dan

Changed fluid, oem filter, removed suction line from resuvior to pump no obstruction, no suction screen on this model, hi limit pressure tested 1800psi, adjusted lift arm control and draft per specs exactly, 2 remotes, problem occurs regardless if remotes are connected or not, problem does how ever occur quicker with more weight on lift arms also standing pressure is higher with increased weight (200psi no weight to 800psi disc mower hooked up) guage is in t block pressure side of pump

 

[TheOldHokie]

Changed fluid, oem filter, removed suction line from resuvior to pump no obstruction, no suction screen on this model, hi limit pressure tested 1800psi, adjusted lift arm control and draft per specs exactly, 2 remotes, problem occurs regardless if remotes are connected or not, problem does how ever occur quicker with more weight on lift arms also standing pressure is higher with increased weight (200psi no weight to 800psi disc mower hooked up) guage is in t block pressure side of pump

I am sorry but I can't follow much of that.

I am not even clear on what the problem is. Is the problem loss of lift after the tractor runs and warms up?

Please show a picture of the gauge whete it iz hooked into the pump.

i have no idea what that valve sitting on the fender is supposed to be. Where did it come from and what does it have to do with your problem?

Dan

 

[North Idaho Wolfman]

I need the serial number of the tractor as it appears from just the picture of the pump it's not the standard M6950.

One thing I have gleaned from the Blue prints it that does not have a normal three point setup.
It actually uses the lower three point arms to sense the weight on the arms and adjust the three point accordingly.
It's quite the elaborate setup.

Bear with us as we get more technical info to help you out.

Have you checked the lower lift arms (where they connect to the tractor) for any heavy wear or bearing issues?

 

[Russell King]

I am sorry but I can't follow much of that.

I am not even clear on what the problem is. Is the problem loss of lift after the tractor runs and warms up?

Please show a picture of the gauge whete it iz hooked into the pump.

i have no idea what that valve sitting on the fender is supposed to be. Where did it come from and what does it have to do with your problem?

Dan

Here is what I think his problem is from reading through the thread

Tractor hydraulic pump has the gauge TEED in the pump output line.
Start tractor and the gauge shows ZERO pressure.
Lift anything and pressure goes to 1000 PSI on gauge.
I THINK the gauge then continues to show the same lift pressure (I don’t see how this could happen).
Then the pressure gauge slowly bleeds pressure off as the pump is working against the constant pressure.

So I would state the problem as: Why is the pump having to hold pressure after lifting any load?

Should the pump go back to Zero PSI when the lift is complete and the valve is released?

He has checked for a strainer and there is not one.
He has changed fluid and filter (in hydraulic system). Not sure what fluid but OEM filter. (Are there TWO different hydraulic filters on this model tractor?)
He has confirmed that the pressure can go up to 1800 PSI.
He has confirmed there is no obstruction on the pump inlet side.
He has 2 remote valves and they can be removed from system with no change in operation.
He has adjusted the three point feedback rod (or the bypass valve)?
There is DRAFT control on the tractor and it was adjusted also. Feedback or bypass?
I am not sure if there is a FEL (front end loader) on the tractor or not. No mention of that.
No mention of backhoe on tractor.

He states that there is no bypass being activated and that makes some sense to me unless he is trying to lift more than tractor design allows. But why is pressure being held in the pumps output line when no valve is being used?

@1fishinrogers - please confirm that I have basically gotten the problem stated correctly and that there is or is not a backhoe or FEL on the tractor.

If you can post more pictures of the hydraulic system and the valves on the tractor (in place and plumbed as they need to be for operation.

Can you eliminate all extra hydraulic systems and go to just the three point system?

 

[TheOldHokie]

Here is what I think his problem is from reading through the thread

Tractor hydraulic pump has the gauge TEED in the pump output line.
Start tractor and the gauge shows ZERO pressure.
Lift anything and pressure goes to 1000 PSI on gauge.
I THINK the gauge then continues to show the same lift pressure (I don’t see how this could happen).
Then the pressure gauge slowly bleeds pressure off as the pump is working against the constant pressure.

So I would state the problem as: Why is the pump having to hold pressure after lifting any load?

Should the pump go back to Zero PSI when the lift is complete and the valve is released?

He has checked for a strainer and there is not one.
He has changed fluid and filter (in hydraulic system). Not sure what fluid but OEM filter. (Are there TWO different hydraulic filters on this model tractor?)
He has confirmed that the pressure can go up to 1800 PSI.
He has confirmed there is no obstruction on the pump inlet side.
He has 2 remote valves and they can be removed from system with no change in operation.
He has adjusted the three point feedback rod (or the bypass valve)?
There is DRAFT control on the tractor and it was adjusted also. Feedback or bypass?
I am not sure if there is a FEL (front end loader) on the tractor or not. No mention of that.
No mention of backhoe on tractor.

He states that there is no bypass being activated and that makes some sense to me unless he is trying to lift more than tractor design allows. But why is pressure being held in the pumps output line when no valve is being used?

@1fishinrogers - please confirm that I have basically gotten the problem stated correctly and that there is or is not a backhoe or FEL on the tractor.

If you can post more pictures of the hydraulic system and the valves on the tractor (in place and plumbed as they need to be for operation.

Can you eliminate all extra hydraulic systems and go to just the three point system?

I cannot make any sense out of his pressure tests. Rather than try and trouble shoot his trouble shooting I would like a simple statement of the problem.

Forget tje remotes for now. What is not working on the 3pt.?

When in position control does it lift a load when cold.

Does it stop lifting when hot?

Will it hold the load once its raised or does it bleed down.

Answer those three questions and post a picture of the gauge hookup and we will hopefully have a pathway forward.

Dan