MX5800 FEL slow

[eod99]

I have a MX5800 HST 1089hrs, has Kubota 3rd function. I was removing my grapple to install pallet forks and noticed my grapple would not open, and like everything around here no time to diag had to load trailer. So I put forks on loaded trailer and as I finished I noticed my fel was going extremely slow up and down but tilt was normal speed and if I shoved stick into "float" mode it would lower quickly or if I tilted while lowering or raising it would go at normal speed. So I am going to start troubleshooting in the a.m.
Should I look at 3rd function electrical 1st or hydraulic side? I have the service manual but it has nothing on 3rd function

TIA

 

[North Idaho Wolfman]

First thing to check is any quick disconnect on the loader connections.
Second thing to check is that the three point is not is the uppermost position and see if that helps your situation.

 

[TheOldHokie]

First thing to check is any quick disconnect on the loader connections.
Second thing to check is that the three point is not is the uppermost position and see if that helps your situation.

Add check that any rear remote valves are in neutral to that list.

Dan

 

[eod99]

Ok tractor has no rear remotes. I checked quick couplers where grapple plugs in I manually pushed both check balls in fluid released outta both and now fel works like it should. 3pt lever is not pinned all the way up.
Thanks for advise, is there a schematic of this hydraulic system that has testing procedures if anything else happens?

 

[TheOldHokie]

Ok tractor has no rear remotes. I checked quick couplers where grapple plugs in I manually pushed both check balls in fluid released outta both and now fel works like it should. 3pt lever is not pinned all the way up.
Thanks for advise, is there a schematic of this hydraulic system that has testing procedures if anything else happens?

Get a copy of the WSM. It has detailed information on the hydrauluc system but you have to "think your way" to diagnostic procefures. The system is very simple and easy to analyze if you have a basic understanding of hydraulics.

In this case it sounds like your third function valve msy have been stuck and not returning to neutral which blocks the outflow on the boom section of the loader valve. No outflow = no lift or lower.

Dan

 

[eod99]

Get a copy of the WSM. It has detailed information on the hydrauluc system but you have to "think your way" to diagnostic procefures. The system is very simple and easy to analyze if you have a basic understanding of hydraulics.

In this case it sounds like your third function valve msy have been stuck and not returning to neutral which blocks the outflow on the boom section of the loader valve. No outflow = no lift or lower.

Dan

So my wsm has nothing on third function valve is there a service manual for third function. Once I release pressure I am guessing it released valve, since originally my grapple wasn't working if I hook it back up should operate like designed now

 

[TheOldHokie]

So my wsm has nothing on third function valve is there a service manual for third function. Once I release pressure I am guessing it released valve, since originally my grapple wasn't working if I hook it back up should operate like designed now

Your third function is just a single dpool AUX valve fed by the PB port on the loader valve. It in turn feeds the 3pt valve.

Pencil it in to the circuit diagram in the WSM. If you post a good picture of the diagram I will do that for you.

Dan

 

[eod99]

Your third function is just a single dpool AUX valve fed by the PB port on the loader valve. It in turn feeds the 3pt valve.

Pencil it in to the circuit diagram in the WSM. If you post a good picture of the diagram I will do that for you.

Dan

Ok as fast as I get back to book I will do that, thank you........

 

[TheOldHokie]

Ok as fast as I get back to book I will do that, thank you........

You are welcome. I was impressed you knew how to test the cylinders. You are definitly not a hydraulic dummy

Read the description of the loader valve functions carefully. The boom section is in series with the bucket section and the bucket spool dump function is regenerative. That can produce symptoms that confuse most people.

Dan

 

[eod99]

You are welcome. I was impressed you knew how to test the cylinders. You are definitly not a hydraulic dummy

Read the description of the loader valve functions carefully. The boom section is in series with the bucket section and the bucket spool dump function is regenerative. That can produce symptoms that confuse most people.

Dan

Here are two I found concerning the front block

 

[TheOldHokie]

Here are two I found concerning the front block

Thats good. I will add the loader and 3rd function circuits to the schematic. Your operators manual describes the use of the outlet block itself.

Dan

 

[TheOldHokie]

Here is the updated schematic showing loader and third function valves. Note that the hydraulic outlet block off plate has been replaced with a loader adapter plate with the three ports described in your operators manual.

 

[eod99]

Here is the updated schematic showing loader and third function valves. Note that the hydraulic outlet block off plate has been replaced with a loader adapter plate with the three ports described in your operators manual.

View attachment 172242

So here's a dumb question, I looked at complete section of the WSM manual and it does not go in depth about the fel, but gives test procedures and complete break down for pump and rear 3 point lift, so am I understanding correctly that basically fel is robbing from 3 point rear lift/hydraulic cylinder under the seat and dumping back into hydraulic "reservoir"?

 

[TheOldHokie]

So here's a dumb question, I looked at complete section of the WSM manual and it does not go in depth about the fel, but gives test procedures and complete break down for pump and rear 3 point lift, so am I understanding correctly that basically fel is robbing from 3 point rear lift/hydraulic cylinder under the seat and dumping back into hydraulic "reservoir"?

There are no dumb questions.

Kubota tractors have open center hydraulic systems. In an open center system the valves are plumbed in series or "daisy chained".

In that diagram pump flow goes to first valve (loader), through it to next valve (3rd function), through it to next valve (rear remotes), through it to last valve in chain (3pt), and through it back to reservoir.

That flow path is called the neutral (or power beyond) circuit and all valves get the full flow frim the pump. But the valve closest to the pump gets priority over downstream valves. When the loader valve is shifted (moved out of neutral) the flow gets diverted to the loader cylinders and then back to reservoir temporarily blocking (disabling) all down stream valves. When the loader valve is returned to neutral the flow to down dtream valves is restored.

Now I just lied to you. Thars how a normal system works. The Kubota loader valve is a hybrid. The bucket section works as I just described but the boom section does not. When the boom section is shifted flow gets diverted to the cylinders BUT the return flow goes back into the neutral (power beyond) circuit not reservoir and is passed to down stream valves.

How all these valves interact gets very messy and I dont want to overload you too much right now. Study the description in the WSM of how the loader valve works some more keeping that neutral (PB) circuit vs reservoir (tank) idea in mind. Then if you have more questions fire away.

Dan

EDIT: If you dont have the WSM for your loader download this one. Its for the LA525 but it covers the basic operation of most Kubota loader valves.

https://www.kubotabooks.com/AutoIndex/index.php?dir=Loaders%20and%20buckets/&file=LA525%20LA765%20WSM.pdf

 

[eod99]

There are no dumb questions.

Kubota tractors have open center hydraulic systems. In an open center system the valves are plumbed in series or "daisy chained".

In that diagram pump flow goes to first valve (loader), through it to next valve (3rd function), through it to next valve (rear remotes), through it to last valve in chain (3pt), and through it back to reservoir.

That flow path is called the neutral (or power beyond) circuit and all valves get the full flow frim the pump. But the valve closest to the pump gets priority over downstream valves. When the loader valve is shifted (moved out of neutral) the flow gets diverted to the loader cylinders and then back to reservoir temporarily blocking (disabling) all down stream valves. When the loader valve is returned to neutral the flow to down dtream valves is restored.

Now I just lied to you. Thars how a normal system works. The Kubota loader valve is a hybrid. The bucket section works as I just described but the boom section does not. When the boom section is shifted flow gets diverted to the cylinders BUT the return flow goes back into the neutral (power beyond) circuit not reservoir and is passed to down stream valves.

How all these valves interact gets very messy and I dont want to overload you too much right now. Study the description in the WSM of how the loader valve works some more keeping that neutral (PB) circuit vs reservoir (tank) idea in mind. Then if you have more questions fire away.

Dan

EDIT: If you dont have the WSM for your loader download this one. Its for the LA525 but it covers the basic operation of most Kubota loader valves.

https://www.kubotabooks.com/AutoIndex/index.php?dir=Loaders%20and%20buckets/&file=LA525%20LA765%20WSM.pdf

That is extremely helpful and I greatly appreciate it, I will print this and add it to my collection. And yes I will be back with more questions.

 

[TheOldHokie]

And yes I will be back with more questions.

I was sure you would be

Dan