L3130 Three Point Hitch Issue

[dangier_VA]

Got the WSM today and have been looking through it (~700 pages!). It does confirm that the 2700 psi reading I recorded on the loader control block is in the ballpark. Have a lot more reading to do. One troubling note, I pulled the new hydraulic filter to make sure I removed the dust cover prior to installing originally. Dust cover was not an issue. However, the hydraulic oil that came out was milky like it had water in it. This is the new hydraulic oil and the tractor has never been in water. Old hydraulic oil was clean when drained. After setting for 1/2 hour, the oil cleared up-Air in oil due to cold start? Warmed the tractor up and checked the trans dip stick and could not see any air in oil-just oil on stick. Three point hitch still slow.
OK, now back to reading the WSM.
David

 

[dangier_VA]

Thought I would provide an update: Still struggling with the weak operation of the rear 3 point hitch. Have WSM and making time to study it. As I mentioned above, I have 2700 psi at front hydraulic block for loader operation. In running the engine, the hydraulic oil has gotten warm and I can feel the warm piping all the way back to the rear hydraulic block. Relief from front hydraulic block has stayed cold so I am not loosing pressure back to sump from there. The connecting lines are a banjo bolt and I do not have a test adapter, but fairly sure front hydraulic block is ok. Now, the rear hydraulic block that feed the rear 3 point hitch is another story. From the WSM, I have pulled everything possible without taking the cover off the trans housing. Pulled the two accessible check valves and found some hardened thread compound inside (cleaned that out). Checked the cylinder relief valve and that looked good-didn't take apart as one needs an injector tester with relief valve adapter to check/reset pressure. Hooked everything back up and tried. No go-still very weak 3 point hitch operation (have to run engine up to 2500 rpm to get any movement).
I feel like I am loosing pressure (flow), in the main 3 point lift control block. Hydraulic lines get warm to the block. Have breakdown in WSM, but a little leery to tear down yet. Trying to explore all possibilities first.
Anyone have any experience like this?
Thanks,
David

 

[PapaPerk]

Thought I would provide an update: Still struggling with the weak operation of the rear 3 point hitch. Have WSM and making time to study it. As I mentioned above, I have 2700 psi at front hydraulic block for loader operation. In running the engine, the hydraulic oil has gotten warm and I can feel the warm piping all the way back to the rear hydraulic block. Relief from front hydraulic block has stayed cold so I am not loosing pressure back to sump from there. The connecting lines are a banjo bolt and I do not have a test adapter, but fairly sure front hydraulic block is ok. Now, the rear hydraulic block that feed the rear 3 point hitch is another story. From the WSM, I have pulled everything possible without taking the cover off the trans housing. Pulled the two accessible check valves and found some hardened thread compound inside (cleaned that out). Checked the cylinder relief valve and that looked good-didn't take apart as one needs an injector tester with relief valve adapter to check/reset pressure. Hooked everything back up and tried. No go-still very weak 3 point hitch operation (have to run engine up to 2500 rpm to get any movement). I feel like I am loosing pressure (flow), in the main 3 point lift control block. Hydraulic lines get warm to the block. Have breakdown in WSM, but a little leery to tear down yet. Trying to explore all possibilities first. Anyone have any experience like this? Thanks, David

Have you checked pressure from cylinders back? Start from problem and work backwards. Sounds like a tough problem.

 

[dangier_VA]

Have you checked pressure from cylinders back? Start from problem and work backwards. Sounds like a tough problem.

The three point hitch cylinders are connected with a short hose to the rear cylinder block-nothing in between. There is not a lot of noise like hydraulic fluid squeezing through a pinch point (ie relief valve). WSM shows internal check valves that are hydraulically operated to relieve pressure. Kind of wondering if of one of them is stuck.
Thanks,
David

 

[jimainiac]

Still wondering if you got your 3pt hitch problem solved, and wondering if it was just a crazy coincidence that it happened right after you did the fluid change.
I know how frustrating the search can be, but you seemed to be getting close through the process of elimination.

 

[dangier_VA]

Jim,

Haven't had a lot of time to work on it, so have been lax in spending "shop time". Did look at it yesterday and decided to take the cylinder relief valve apart as there seemed to have more noise than normal when trying to get the 3 point hitch to raise (like it was bypassing when it shouldn't). Counted the threads and unscrewed everything. Inside was spotless. Again while running the tractor, the hydraulic line from the front loader control block was warm to the rear 3 point hitch control block. Piped bypass from front control block to trans sump was cold, so it is not bypassing. Everything still points to the rear hydraulic control block is bypassing to the trans sump. So, I am at the point of pulling the 3 point hitch control block and trans cover and check that out. Thinking I might have a cut o-ring on the spool valve.... Or something like that. Kubota has special tooling to check hydraulic pressures with lines in place. Has to be a coincidence that this showed up after the servicing-I hope. Just been dragging my feet on tearing into the trans.
Thanks,
David

ps: How is the weather up there? My family came from Newport, VT, and have spent a few weeks there in the summers during the '60's. Wind always blowing....

 

[dangier_VA]

Great News! At least I think. Got up the courage to tear into the rear hydraulic control valve for my non-functional 3 point hitch on my L3130. Found a wadded up screen in one of the internal check valves in the rear hydraulic control valve. This screen was holding the check open and bypassing the control valve dumping fluid into the trans sump. Screen is not shown on the Kubota WSM exploded diagrams, but is shown on Messicks diagrams and not shown as a stock item. Since this is already in the hydraulic system after the filter, hydraulic pump, and front hydraulic control valve for loader, I would assume it is there just for safety? Have thoughts of just leaving it out.
Anyone care to comment?
Thanks,
David

 

[jimainiac]

Wow, it looks like you're on the right track now. I think you found the "smoking gun". I think that's pretty weird that it doesn't show up in the Kubota shop manual, but I've been disappointed with with the Thoroughness of the Kubota shop manual and parts manual, although they're better than nothing. I think this would be the time to get a ruling from a Kubota dealer, or maybe two, for a second opinion, on the screen. Knowing how close the tolerances are in the hydraulic system, and especially the HST, I wouldn't dare leave the screen out, from wherever it came from.
Good news!

 

[dangier_VA]

Jim,
Finally got it all back together (twice-once just for practice . The rear hitch will work at an engine idle now. You probably can't see, but I am smiling ear to ear.... Was worried about what I might find once I got in there. Just kind of wondering if the screen should have been before the hydraulic filter instead of where it was. It is kind of coarse for hydraulic use. It was located in a recess on the incoming hydraulic line where the rear hydraulic block attaches to the bottom of the trans cover. The only thing holding it in was an o-ring! Glad I took the plunge and jumped into it. Kind of wonder how many kubota owners could have this issue in the future?
Thanks for your input.
David

 

[jimainiac]

Man, what an ordeal, but all's well that ends well. I went back to your original post to see that you bought the tractor new, so it seems like that screen must have been in it all along. I'd still want to figure out where it's supposed to be. You deserve a lot of credit for tracking it down, and it was a good excuse to get the WSM, at least. Congratulations!
As for the weather up here in northern New Hampshire, it's all over the map - rain yesterday, snow today, and the other week 26 below. Like they say, if you don't like the weather around here, wait five minutes.