L3000DT Loader Hydraulic Problem

[BillCT]

Our club has an older L3000 that I'm trying to get repaired. We've had an ongoing issue with the bucket hydraulics working slower and slower over time until now they won't lift the empty bucket. I've had Kubota rebuild the cylinders, I've changed the fluid and cleand the strainer and even purchased a new control valve. With each repair job there has been some improvement but it doesn't last. I'm wondering if there's a pressure relief valve someplace that could be stuck?? The three point hitch works perfectly, picks up our mower deck no problem. I do know that if the lever for the 3 point is too far in the up position the pump will wine like it dead headed so we always back off on it a little and the wine stops.
I do know that the linkage that works the bucket control valve is really sloppy from years of use, I asked Kubota yesterday if it's critical that the plungers on the control valve work precisely together and he said yes. I had the impression he would have said yes to anything but he could be right I guess. Just wondering about other things before I start throwing parts at it again. Thanks

 

[je1279]

Have you replaced the quick connect fittings for the loader on both the tractor and loader side?

 

[Dave_eng]

What model is the loader?
Did the tractor come from Kubota with the loader installed?
Is the bucket operation as weak as the loader arms?
Any hydraulic hoses changed? A hose put in the wrong place can cause problems.
Loader valves come with a built in relief valve so if the loader valve was changed that rules out the relief valve particularly when you state the 3 pt hitch works well.

In addition to je1279's suggestion re quick couplings, buying a pressure gauge and taking some readings would be appropriate. Cost around $30

Dave

 

[BillCT]

Have you replaced the quick connect fittings for the loader on both the tractor and loader side?

No I haven't touched them. Would they fail and cause something like this??

 

[je1279]

No I haven't touched them. Would they fail and cause something like this??

Over time they can get gunked up due to contamination and not allow the hydraulic fluid to flow as it should. It is certainly the least expensive option to try and then I would follow up with what @Dave_eng said to verify your hydraulic pressure is where it should be if the issue remains.

 

[BillCT]

What model is the loader?
Did the tractor come from Kubota with the loader installed?
Is the bucket operation as weak as the loader arms?
Any hydraulic hoses changed? A hose put in the wrong place can cause problems.
Loader valves come with a built in relief valve so if the loader valve was changed that rules out the relief valve particularly when you state the 3 pt hitch works well.

In addition to je1279's suggestion re quick couplings, buying a pressure gauge and taking some readings would be appropriate. Cost around $30

View attachment 54749

Dave

The loader is an LA4050 and it came with the tractor when we bought it many years ago.
Actually the bucket operation seems stronger than the lift arms, weak but definitely stronger.
Thanks for the picture, I'm thinking tractor supply might have one.
I'll also look into changing the couplings too.
Thanks

 

[BillCT]

Over time they can get gunked up due to contamination and not allow the hydraulic fluid to flow as it should. It is certainly the least expensive option to try and then I would follow up with what @Dave_eng said to verify your pressure is where it should be if the issue remains.

OK will do. It'll take me a few days but I'll let you know.
Thank you

 

[je1279]

OK will do. It'll take me a few days but I'll let you know.
Thank you

No worries. Report back on your findings when you are able.

 

[lugbolt]

each time when you cleaned the screen was there a jelly-like substance stuck to it? Another question, after operating the tractor, is the hydraulic fluid aerated, like it would have tiny air bubbles in it? Some say it looks like water.

 

[BillCT]

each time when you cleaned the screen was there a jelly-like substance stuck to it? Another question, after operating the tractor, is the hydraulic fluid aerated, like it would have tiny air bubbles in it? Some say it looks like water.

I did drain the fluid and replaced it with Kubota fluid, the screen wasn't dirty at all. I flushed it with some kerosene anyway before reassembly.
Good question on the bubbles, but I can't say. I'll check.

 

[BillCT]

no bubbles seen in the fluid.
Well the only quick disconnect is on the main line to the hyd valve, all the hoses are screw on. We haven't changed that disconnect yet but will. We bought a gage and plugged it into that main line and read zero pressure at idle, 700 lbs at 2800 rpm, pretty low. So it looks like either that fitting is bad or the pump has seen better days I guess. Tough working on this thing in the cold, we'll get another fitting and see what happens but it sounds like a long shot wouldn't you folks say?

 

[je1279]

It's just interesting that the 3 point works fine but the loader does not. Also, could you post a picture of your loader valve? From what I can tell, the factory valves did come with quick disconnects. Here is a picture that I found online.

 

[BillCT]

It's just interesting that the 3 point works fine but the loader does not. Also, could you post a picture of your loader valve? From what I can tell, the factory valves did come with quick disconnects. Here is a picture that I found online.

View attachment 54913

Yes I agree with you about the 3 point hitch
OK on the picture.

 

[Dave_eng]

I suggest you make a sketch of the loader valve and show where each hose goes to. Look for markings Like P, T, T2 cast into the loader valve body.

I am not concerned about the 4 lines going to the loader cylinders

Also show where you connected the pressure gauge.

Your pressure gauge readings seem more like a Tank port output of the loader valve not the pressures generated by a main pump.

My reaction: a loader valve hose is in the wrong place which is an easy mistake to make.

Tell us more about the new loader valve. Is it supplied by Kubota or elsewhere?

Did it come equipped with a power beyond sleeve or plug?

Make and model number of the new loader valve

Dave

 

[lugbolt]

follow your hoses down to the tractor, where they go in. Some loader installations had a shut-off valve ON the distribution block. Some were a simple on-off valve on the outside of the block, others were a slotted head screw in the block (accessible) that turns 90 degrees.

If you have a valve somewhere on it, turn it one direction or the other.

I thought that the L3000's had an LA450 or LA450S loader? I don't remember if/what kind of valve they had. I do remember the Grand L's had a slotted screw style valve on the tractor's hydraulic distribution block, I just don't recall what the LA450 had.

I have also run into cheap quick connects that fail and restrict flow. A flow restriction is what slows things down, a lot of times a pressure gauge will still show correct pressure but flow rate will be way down--which is why, in hydraulic equipment, one should never rely solely on a pressure gauge's reading by itself.

There is also a possibility that one of the pistons came off inside the cylinder or is otherwise leaking past. I ran into that once. The piston would move but the rod would barely move, mostly because the opposite cylinder was doing a little bit of work, but the system wouldn't flow enough to make it actually do ALL the work with the other one bypassing. That one took a bit to figure out.

Those are beyond the obvious--like attaching hoses improperly which is quite common and extremely easy to do, and real easy to prevent. I like to use colored wire ties but everyone has their own way of doing things.

 

[BillCT]

I suggest you make a sketch of the loader valve and show where each hose goes to. Look for markings Like P, T, T2 cast into the loader valve body.

I am not concerned about the 4 lines going to the loader cylinders

Also show where you connected the pressure gauge.

Your pressure gauge readings seem more like a Tank port output of the loader valve not the pressures generated by a main pump.

My reaction: a loader valve hose is in the wrong place which is an easy mistake to make.

Tell us more about the new loader valve. Is it supplied by Kubota or elsewhere?

Did it come equipped with a power beyond sleeve or plug?

Make and model number of the new loader valve

Dave

OK on the sketch, I'll do that and post it. I had the loader manual today and was trying to follow the lines and compare it to the manual but the pictures in the manual are so poor I can't make any sense out of them.
It kind of does seem like theres a hose in the wrong place but this thing did work fine a couple of years ago.
The loader valve is a Kubota valve with power beyond that we use to angle the snow plow. The power beyond is the only fitting that has a quick disconnect on it.

Pictures below of the valve. The three lines in the picture are under the operators right foot. We put the gage in the top fitting. One of the guys was replacing some cracked hoses today that's why the hoses are absent. We're going to replace those two quick disconnects. We put the gauge in the top connector, we made up a "T" fitting.

 

[BillCT]

follow your hoses down to the tractor, where they go in. Some loader installations had a shut-off valve ON the distribution block. Some were a simple on-off valve on the outside of the block, others were a slotted head screw in the block (accessible) that turns 90 degrees.

If you have a valve somewhere on it, turn it one direction or the other.

I thought that the L3000's had an LA450 or LA450S loader? I don't remember if/what kind of valve they had. I do remember the Grand L's had a slotted screw style valve on the tractor's hydraulic distribution block, I just don't recall what the LA450 had.

I have also run into cheap quick connects that fail and restrict flow. A flow restriction is what slows things down, a lot of times a pressure gauge will still show correct pressure but flow rate will be way down--which is why, in hydraulic equipment, one should never rely solely on a pressure gauge's reading by itself.

There is also a possibility that one of the pistons came off inside the cylinder or is otherwise leaking past. I ran into that once. The piston would move but the rod would barely move, mostly because the opposite cylinder was doing a little bit of work, but the system wouldn't flow enough to make it actually do ALL the work with the other one bypassing. That one took a bit to figure out.

Those are beyond the obvious--like attaching hoses improperly which is quite common and extremely easy to do, and real easy to prevent. I like to use colored wire ties but everyone has their own way of doing things.

Thanks for the suggestions, sorry for the late reply, I don't know why I'm not getting a notification when someone replies, I'll have to check the settings.
I'll check for a valve and see if there's anything, boy that would be simple if the valve was partially closed. I had the cylinders rebuilt this spring by Kubota and it did make a slight difference for a while but never as it should then it gradually got weak again. We're going to replace the quick disconnects as you suggested.

 

[BillCT]

I looked around today for any kind of shut off or flow valve and couldn't see anything. Below is a shot of under the seat where one of the lines goes into the rear end.
Also below is a diagram of where the lines are going from the Valve. Hope it makes sense OK.

 

[Dave_eng]

The loader is an LA4050 and it came with the tractor when we bought it many years ago.
Actually the bucket operation seems stronger than the lift arms, weak but definitely stronger.
Thanks for the picture, I'm thinking tractor supply might have one.
I'll also look into changing the couplings too.
Thanks

I am puzzled because I cannot find a LA4050 loader.
Is it possible it is a LA450S

The following two parts illustrations show how I believe the loader hydraulics are connected to the tractor as part of the loader installation.

This second illustration shows a new rectangular plate 230 clamping hydraulic line 110 above to the rear of the tractor.

Plate 230 has two external hydraulic lines connected to it. The plate or cover becomes a power beyond block first directing main pump flow to the loader valve for use by the loader cylinders and the second line connected to the rectangular cover is returning oil to the rear of the tractor for use by the 3 pt hitch and rear remotes. This second line is actually the power beyond line from the loader valve.

I numbered the 3 critical lines. #1 is almost certainly a tank line dumping relief valve and other unneeded oil from the loader valve back into the transmission or reservoir. #2 & #3 are the big unknowns. From the parts illustration I cannot tell if #2 is connected to the IN port to the loader valve or not. It could be #3. Alternatively #3 could be from the power beyond port on the loader valve providing oil to the rear of the tractor.

Oil is diverted in a loop from the rear of the tractor, through the loader valve and back to the rear of the tractor.

Get these lines swapped and weird things happen.

In looking at your photo placed below it does not look like getting these #2 & #3 lines mis connected at this end is likely. as the lines are formed steel ones. I do not yet have an opinion about these lines being swapped at the loader valve.

Dave

 

[BillCT]

Dave,
First of all, you are correct on the loader model, it is an LA450S. I don't know why I typed that number. Sorry.
Thank you for all your time and explanations here, very valuable information. I printed it out to put in our manual.
Lugbolt had mentioned a flow control valve so we did some reading and searching and found a flow control valve for the loader which was stuck pretty bad almost closed and wouldn't turn, but with a little coaxing it did and now things seem to be working very well. The power beyond had actually stopped functioning and we couldn't angle the plow but after we opened the valve a little it's now working perfectly. The loader lift brings the plow up like it should. So that probably explains why the 3 point hitch was working fine but the loader wouldn't work. Man what an ordeal. Lets hope it stays working.

I appreciate all the input and time you guys spent on this.

Thanks,

Bill