L3130 Three Point Hitch Issue

[JRobyn]

What are the chances that the original little suction hose had a SPRING inside of it to keep it from sucking closed, and you omitted it when you replaced it? It might work fine while the hydr fluid was cool, but once it warmed, softening the hose, perhaps the hose is sucking at least partially closed. ??

- Jay

 

[dangier_VA]

Good thought, but there was not a spring in the original hose. In fact, it looked like a washing machine drain hose. Single braid and the ends of the metal pipe were not aligned with the offset being about 1/2 inch with a 1/2 inch gap covered with the hose. The total flow through the 3/4 inch pipe is only part of the suction line flow. It T's into a larger line from the suction filter going to the hydraulic pump.
Thanks,
David

Edit: Please see my post #11. I have 2700 psi available at the loader control at a fast idle. Lines and control valves from loader feed rear piping to hitch. I seem to have plenty of hydraulic flow and pressures up front. Just need to see what the specs are to check out where I am loosing it. Something is hanging up.

 

[Gordon Gould]

Good thought, but there was not a spring in the original hose. In fact, it looked like a washing machine drain hose. Single braid and the ends of the metal pipe were not aligned with the offset being about 1/2 inch with a 1/2 inch gap covered with the hose. The total flow through the 3/4 inch pipe is only part of the suction line flow. It T's into a larger line from the suction filter going to the hydraulic pump.
Thanks,
David

Edit: Please see my post #11. I have 2700 psi available at the loader control at a fast idle. Lines and control valves from loader feed rear piping to hitch. I seem to have plenty of hydraulic flow and pressures up front. Just need to see what the specs are to check out where I am loosing it. Something is hanging up.

You should get approximately the same 2700 psi pressure at any engine speed. The pump should produce the same pressure independent of speed. Higher RPM's increases the flow but not the pressure if things are normal. You didn't really say that you have less pressure at lower RPM but I thought I should mention this.

 

[Leejohn]

The control valve under the seat, where remote valve hookup there are 2 safetyvalves. The spring might of broke in one, they are just a poppet valve. One other thing that it might be is a o ring for the 3pt control valve is leaking by. There also is a plug on top of the control valve that you might be able check the psi to the 3pt valve. When you get your manual it should tell you if that plug is for checking psi. Look on line for a parts manual and look at the control valve.

 

[dangier_VA]

You should get approximately the same 2700 psi pressure at any engine speed. The pump should produce the same pressure independent of speed. Higher RPM's increases the flow but not the pressure if things are normal. You didn't really say that you have less pressure at lower RPM but I thought I should mention this.

Makes sense. I was just trying to give out as much information as I could. Throttle just happened to be at fast idle while trying to diagnose hitch issue.

 

[dangier_VA]

The control valve under the seat, where remote valve hookup there are 2 safetyvalves. The spring might of broke in one, they are just a poppet valve. One other thing that it might be is a o ring for the 3pt control valve is leaking by. There also is a plug on top of the control valve that you might be able check the psi to the 3pt valve. When you get your manual it should tell you if that plug is for checking psi. Look on line for a parts manual and look at the control valve.

I do have the Messick's parts pdf breakdown and there are a lot of plugs on the 3 pt control valve. Don't want to lose some small critical part at this point. Was going to put the gauge on the control valve output to the hitch, but I already know that the pressure is not there as it does not work like it should. Trying to think of everything I did during this service where I think the problem started. I did take the front loader off the tractor as I needed to do the overdue engine valves check/adjustments. Just undid the quick disconnects and put back on reinstall. Disconnects are color coded so they went back in the same place. Have had the front loader off several times before. Wondering if this is just a coincidence or what!!
David

 

[dangier_VA]

Just wondering, in your posts you say "UDT". Do you actually use UDT or SUDT? The manual specifies SUDT, and even though it's really expensive, I've never dared use anything else. Actually, I guess it's mostly for the HST transmission, and wouldn't matter for the 3ph, and you say the tractor travels okay.

My kubota manual specifies UDT or SUDT for the trans/hydraulic fluid.
David

 

[jimainiac]

If you've been using UDT fluid right along with satisfactory results so far, I guess this is a moot point, but my operator's manual, which covers the whole Grand L model line from 3130 to 5030 does in fact at least "recommend" SUDT. On page 84, under Changing transmission Fluid, step 3 - "Fill with the new KUBOTA SUPER UDT fluid up to the upper notch on the dipstick. (See "LUBRICANTS" in Maintenance section).
On page 67 of the Maintenance section under Transmission case it does indeed say KUBOTA UDT or SUPER UDT fluid*. But one of the notes at the bottom of the page says "We recommend the use of KUBOTA SUPER UDT fluid for optimum protection and performance. (Consult your local KUBOTA Dealer for further detail.) Do not mix different brands or grades."
I took that to mean that they really want SUDT to be used. If I had to guess, I'd say it's probably most important for cold weather operation, such as we encounter up here in Northern New England.
Also, you sound pretty sure that the replacement of the short piece of hose isn't the problem, but it is one of the only things that was changed.
If you haven't had any luck so far, it may be time to put in a call for the detective most extraordinaire, Hercule Poirot, to use "the little gray cells".

 

[jimainiac]

I don't know about anybody else, but I'm wondering how you're making out with your 3ph problem. I hope you've gotten it fixed, but if you haven't, I thought of something that might make your 3ph seem to act differently, and appear to be weaker. If you had taken your top link off for better access when you did the fluid change, and the top link was put back in a different one of the three mounting holes, it may affect the ability to raise an attachment. It changes the geometry of the assembly, I think.

 

[dangier_VA]

I don't know about anybody else, but I'm wondering how you're making out with your 3ph problem. I hope you've gotten it fixed, but if you haven't, I thought of something that might make your 3ph seem to act differently, and appear to be weaker. If you had taken your top link off for better access when you did the fluid change, and the top link was put back in a different one of the three mounting holes, it may affect the ability to raise an attachment. It changes the geometry of the assembly, I think.

Jim,
Appreciate the follow-up. Have shop manual on order and waiting for that. Want to check the hydraulic input pressure for the rear hitch. With the many plugs and taps on the top of the transmission housing, I don't want to pull the wrong plug out and have springs, etc., fly and get lost.
I didn't change anything on the tractor when servicing the hydrofluid (other than fluid and filters). Did notice a connector broken off the side of the hydro trans (right side, about halfway back). Don't recall seeing that broken, but who knows. Wires just hanging for now. As soon as I get the manual, I should be able to start somewhere and find out what is happening.
Thanks,
David

 

[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.