2850 GST Hydraulic Issue

[RExd]

Hi everyone,

I'm facing a really tough hydraulic issue on my Kubota L2850 GST and I could really use some expert advice because the tractor is currently stuck in the middle of a field.



Everything started a few weeks ago when I tried to yank out a tree stump using the power of my 3-point hitch. Right after that heavy strain, the whole hydraulic system went extremely weak and slow.

As a first step, I did a partial fluid drain and replaced the hydraulic filter. It actually worked great for about half an hour, but then the problem came back worse than before. Now, the tractor is completely immobilized in my field because I have no forward or reverse gears at all, and no hitch movement whatsoever.

I did another drain, but it's impossible to know the exact oil level since I can't see anything through the unreadable inspection sight glass.
(The level is below my finger : )

However, after running the engine for just 2 to 5 minutes, I can see the oil looks completely foamy when looking directly through the filler neck between my legs.



To investigate, I pulled apart and cleaned the divider/regulating block near the right wheel, as well as the filter housing unit (including the two plugs/bolts acting on the internal spools). I didn't notice any obvious damage or debris there.

Since the problem persisted, I ended up ordering a brand new hydraulic pump from FridayParts and installed it, making sure the suction line rubber hose and clamps were tight. Unfortunately, even with the new pump, there is absolutely no improvement. It’s actually worse now: before the pump swap, I could at least get a tiny bit of hitch movement, but now I have absolutely nothing.

Since it’s a GST transmission and everything is down, I'm a bit lost on what to check next.

Has anyone experienced this kind of total hydraulic failure after a heavy mechanical overload on the 3-point hitch? Is there any specific trick to bleed or prime the system, or could something have cracked internally inside the regulating block due to the massive strain?

Thanks a lot for your help, I'm running out of ideas here!

 

[North Idaho Wolfman]

#1 you have WAYYYYY to much fluid in it if it's up to your finger.
When you replaced the "including the two plugs/bolts acting on the internal spools" bolts did you putt them back in exactly the same amount of threads? If not you will need a pressure test kit to set the pressures.

I take it you also have no steering control.

Loosen the large filter slightly, start the tractor, if flid starts to flow tighten the filter, then try all the hydraulics.
If that works you have either fixed it (vapor locked) or you have a suction side leak.

If you do not get fluid to flow, check back in.

 

[RExd]

Thanks for the quick reply!

About the fluid level: Oh, wow, good to know. I thought the fluid had to be way higher since I couldn't see anything in the sight glass. I will drain the excess fluid right away to see if it stops the foaming issue. Any idea where should be the level normaly ? I guess on the redline but maybe I'm wrong ?



About the spool bolts: I tightened them but I didn't count the exact number of threads before removing them. I might have messed up the pressure settings there. I will order a pressure test kit as soon as possible to fix this. To reset those spool bolts properly and check the main lines, do you have any specific kit recommendations or gauge specs I should look for that will fit this tractor?

Also, since I've never done a full pressure calibration on a GST regulating block, any advice on how to actually do it safely or where the exact test ports are located would be amazing.

Steering: You are right, I have absolutely no steering control either. Total loss everywhere.

The filter test: I'm going out to the field asap to try your trick with loosening the large filter and starting the engine. I'll report back when it's done to tell you if fluid flows or not

 

[Russell King]

There is a site called Kubota Books dot com that has the Work Shop Manual (WSM). You can download it for free but they like to get a donation to help with site costs.

The orange words above are a link to the index page that looks like this. You will need to move down to the correct location to see this cropped area.



I assume you can get to it from France and the WSM is probably in English and French. It will provide good trouble shooting guidance and steps to perform tests.

Good Luck!

 

[RExd]

Thanks for the reply. I've already downloaded and examined them, but I'm having a hard time pinpointing exactly where my problem could be.

I just recorded a video after draining about 10 liters of fluid and trying to loosen the filter as you recommended. What are your thoughts on this?