Kubota M7040 4WD Utility Tractor Hydraulics

[5030]

Sounds fishy to me....

 

[DJM1591]

Is it possible for you to loosen/disconnect one of the pump discharge lines, start up tractor and verify if the pump is working. Just do this quickly so if pump is working you don't damage it.

Going to do that this weekend when I get to where the tractor is. I am wondering if it could be a hydraulic relief valve failure .

 

[big bubba]

you might post or transfer your thread over to the Hyd discussion forum,
The pre 4 tier M series is a solid choice for utility work, good luck on issue

 

[rScotty]

One simple thing to check is the suction hose from hydraulic sump to the hydraulic pump inlet.
On some tractors - especially HSTs - that suction line is an inaccessible internal passage, but on many models the suction line is an actual external hose. Even the smallest pinhole air leak can prevent the pump from drawing hydraulic fluid up from the sump.

The same thing can happen with a spin-in hydraulic filter with a leaky seal.

As you say, it could also be a hydraulic relief valve failure, but my experience is that relief valves make a definite loud sound when their small orfice is suddenly trying to handle full flow. Worth looking for, though.

After that I'd rig up a hydraulic T fitting, a 5000 psi pressure gauge, and a handful of various QA and threaded adapters so as to start looking at pressures. BTW, Kubota's shop manuals usually have a really good chapter on hydraulics with illustrations of how it flows.
Also in favor of the shop manual is that I'd be surprised if the larger Kubotas didn't have a selection of pressure test points.....that would save you from needing all those adapters.

rScotty

 

[DJM1591]

When checking easy things did you install new hyd filters?

Done that, all new fluid and filters.

 

[rScotty]

Done that, all new fluid and filters.

How long before the hydraulics stopped working? Sometimes it helps to go back to what happened right before something changed. At least one of the hydraulic filters is on the suction side.

 

[ovrszd]

Well,,, even though I can't find a manual for your tractor I want to pass on this website for anyone else who's equipment might be listed. Excellent link to many, many, many Kubota manuals.

Index of Kubotabooks/

 

[Smokeydog]

Same Kubota oil and filters for hydraulic and HST?
Careful to check old filter gaskets came off beforehand installing new filters?
Filters tight?
Have had a rubber elbow on the suction line develop cracks that let air in but never dripped? Could not see cracks until removed. Any external rubber on the suction side is suspect. Easy stuff first. Hope for an easy fix.

 

[DJM1591]

How long before the hydraulics stopped working? Sometimes it helps to go back to what happened right before something changed. At least one of the hydraulic filters is on the suction side.

Well, my son was last to use it a few weeks ago. He said it was running as it should when he got off it. You know how that goes .

 

[ovrszd]

Well, my son was last to use it a few weeks ago. He said it was running as it should when he got off it. You know how that goes .

I'm an optimist. I've never heard of a hydraulic pump failure on these tractors. And, because you lost movement and 3pt/remote hydraulics at the same time it seems to be a "system" failure. I'm still hoping we can find a cheap solution.

Thank you very much for staying with us on this issue. Very common here on TBN to see a new member post a question and then never hear from them again. Hopefully you will keep us informed of progress.