4400 Hydraulic Issues - New pump, or no?

[christhefur]

Hey Crew,
Our Kubota L4400 has mostly lost hydraulic function (including steering). It happened suddenly. No leaks, fluid level is fine. Before I order a new pump, is there anything else I should check, any other known issues?
This tractor has a shared hydraulic/ gear/ trans sump. Fluid still looks great.
It has under 800 hours on it.
It has been serviced regularly (grease, oil, filters) by a ticketed mechanic.
Still hoping it might be something simple.
The steering will work somewhat intermittently, as will the loader, but slightly and in 'pulses.' The pump was making some unusual noise, like loud whining, when it happened. Still no leaks.
Also, it is winter here, it was below freeing when this happened (I was clearing snow). It's out in the field, due to no steering.
Thanks in advance for any wisdom/ tips/ advice!!
It seems to me that the pump should last long past 800 hours, but... who knows, I guess.
-ChrisTF

 

[North Idaho Wolfman]

More than likely you have a suction leak.
Look at the large lines the feed the pump, typically its the rubber hose connections that have the biggest issues.
Could also be a filter issue.

 

[TheOldHokie]

Hey Crew,
Our Kubota L4400 has mostly lost hydraulic function (including steering). It happened suddenly. No leaks, fluid level is fine. Before I order a new pump, is there anything else I should check, any other known issues?
This tractor has a shared hydraulic/ gear/ trans sump. Fluid still looks great.
It has under 800 hours on it.
It has been serviced regularly (grease, oil, filters) by a ticketed mechanic.
Still hoping it might be something simple.
The steering will work somewhat intermittently, as will the loader, but slightly and in 'pulses.' The pump was making some unusual noise, like loud whining, when it happened. Still no leaks.
Also, it is winter here, it was below freeing when this happened (I was clearing snow). It's out in the field, due to no steering.
Thanks in advance for any wisdom/ tips/ advice!!
It seems to me that the pump should last long past 800 hours, but... who knows, I guess.
-ChrisTF

Start by purchasing a $20 hydraulic pressure gauge and pressure testing the pump. Make sure you do that ahead of any pressure reliefs or steering flow dividers. That will tell you if the pump is the problem.

Dan

 

[Roadworthy]

Once in a great while a new filter will collapse. You can lose pressure there. A pump failure is pretty rare.

 

[christhefur]

Hi Everyone, posting here in case others have this problem. We solved it - for now!
It was the filter. We had just changed the fluid and filter and it was completely clogged. Replacing the filter solved it.
However, the PTO stopped working. We brought it in to the dealer, the split the tractor and said the PTO clutch, all the mechanical workings of the tractor are mint - but the brand new filter is clogged again!
The dealer is totally stumped, we are too.
So, still trying to totally solve, but it wasn't the pump or any of the Kubota mechanical parts.
-ChrisTF

 

[Nicksacco]

I'd be curious to know what was inside the filter!

 

[North Idaho Wolfman]

You need to cut the filter open and look for brake lining.

 

[christhefur]

We cut it open, the filter was clogged with goopy gunk. None of it seemed to be metal. The dealer said the clutches, brakes, and everything is as-new.

 

[North Idaho Wolfman]

What fluid has it been run with?
Is there any chance someone has a gripe against you and have dumped something in it?

 

[christhefur]

We were using spec fluid. We suspected that perhaps someone made a mistake with fluid but couldn't find any evidence of it, other than the goop in the filters. I suppose anything is possible. Mystery continues. Will post if the dealer solves it.

 

[Nicksacco]

Thick goop? This makes no sense to me either.

I found these articles, however since you all say that you changed the fluid and used spec fluid I doubt it was incorrect or bad fluid. I was curious as to what could make hydraulic fluid get thick.

Most Common Causes of Hydraulic Systems Failure | YorkPMH

The leading causes of injury on an aerial lift are the result of platform tip-overs, ejections & caught-between accidents. Learn more.

yorkpmh.com

Hydraulic Pump Overheating: Hazards, Causes, and Solutions for This Problem

Learn about the hazards of a hydraulic pump that runs too hot, the most common causes of this problem, and the ways to remedy this common pump issue.

www.quadfluiddynamics.com

Quad Fluid Dynamics Inc | Hydraulic Services | Ohio

Quad Fluid Dynamics offers Hydraulic Cylinder Rebuilding, Hydraulic Pump Repairs, CNC Component Repair, Hydraulic Press Services, and Gear Boxes for people throughout Ohio. Contact us in Ohio for more information

www.quadfluiddynamics.com

I dunno, I wonder if something inside the machine has broken down - but "goopy" makes me think of something like thick grease - and where would a substance like that come from?
Did you use a name-brand filter?

Pictures? What was the goop color? Perhaps have it sent to a lab?

 

[Grandad4]

We were using spec fluid. We suspected that perhaps someone made a mistake with fluid but couldn't find any evidence of it, other than the goop in the filters. I suppose anything is possible. Mystery continues. Will post if the dealer solves it.

Just to clarify. Does "spec fluid" mean you used a) actual Kubota SUDT2 or
b) something that says it meets SUDT2 specs?

 

[Russell King]

I f you still have the filter and goop I would find a laboratory to test it out and see what it is. I think I would start looking into oil analysis lab and see if they can help you with what created the problem in the fliter.