L4200 Hydraulic problems

Bryson Lamboy

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Dec 30, 2019
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I have an Kubota L4200 gst 4x4 rops. I have been to multiple dealerships and no one can help me. My tractor is loosing power under a load even driving up a slight grade in high gear. I notice it more in higher gears especially driving up hills. I have replaced the clutch and pressure plate, and the clutch pack. I have checked the pressure at the pump and it is good but I have no clutch pack pressure at all and do not know how the fluid flows through the gst valve assembly.
Has anyone else experienced these problems?
 

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
Do you have the WSM for it?
It has the procedures and diagrams that lay it all out.
Ask if you don't have one, I've got a copy kicking around.

When you put a clutch pack (assuming you mean the hydraulic clutch pack) in it, did you do the whole pack or just the clutch disks?

Did you replace any other parts when you were into it for the clutch pack?

What fluid and filter are you running in it?
 

Bryson Lamboy

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Dec 30, 2019
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I have replaced the entire clutch pack, and the manual clutch.

I do not have a WSM and I am running a wix filter and traveller brand hydraulic fluid.
Inside the gst valve assembly I found a stuck valve so I cleaned it up but still not working.

It seems like pressure is leaking from somewhere.
 

North Idaho Wolfman

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Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,676
5,106
113
Sandpoint, ID
I have replaced the entire clutch pack, and the manual clutch.

I do not have a WSM and I am running a wix filter and traveller brand hydraulic fluid.
Inside the gst valve assembly I found a stuck valve so I cleaned it up but still not working.

It seems like pressure is leaking from somewhere.
#1:
I would get a Kubota Hydraulic filter, and Kubota UDT fluid, or Mystik JT-5 fluid.

The filter quality and the fluid quality are very important in a GST, too thick of fluid and it simply won't shift or run properly.


#2:
You're going to need to get some pressure reading to know where to go next.
 

Bryson Lamboy

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Dec 30, 2019
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I still don’t understand why I have no clutch pack pressure.
I check the port on the side of the gst valve assembly, all my other pressures are good except the clutch pack which I think is why it is not pulling in high gear.
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,842
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Mid, South, USA
What's your clutch pack pressure?

The WSM outlines how and where to test. WSM (the correct one) is required for proper diagnosis of GST. In the book, it also gives you a diagram of the system(s) that control the gst pack and gst valves.

Traveler fluid is hydraulic fluid, is not great for hydraulic clutches. Likely already soaked into everything so it's too late. Should have used Super UDT2 and nothing else. Yeah it costs more, and for good reason. You get what you pay for.

Also that traveler fluid is different in it's viscosity and lubrication characteristics. I know when tractors have it in them just by the feel of the GST. Seen many many stuck valves in M40's and MX's and Grand L's due to junk traveler fluid. On the M40's with cab, gotta lift the cab to get to the valve in a lot of cases, so owner saved $150 total using junk fluid, then when I have to pull the cab up to access the valve, just spent his savings and a whole lot more to offset it. Never seen one stuck that used super udt2, that I can remember-and I'd probably have remembered.

compatible with kubota my foot. What specification are they "compatible" with? They don't list a specification. Or maybe the bucket that it's shipped in is compatible. You never know because they don't tell you, which is exactly why I said it might as well be knockoff garbage from china.
 

North Idaho Wolfman

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Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,676
5,106
113
Sandpoint, ID
Bryson,

We're telling you, you need to,
First change fluid and filter as that could be causing all your issues.

After that, Second would be to give use us all the pressure readings at all the ports, exact numbers please.

And also any details like does it slam or slide into gear, does it stop abruptly or shutter, how far out do you have to release the clutch pedal in order for it to engage, Like at the top (all the way in) or at the bottom (all the way out)?
Little details can make a big difference.
Details like how does the PTO work, How does it engage? Have you tested pressures there?
 

Bryson Lamboy

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Dec 30, 2019
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I checked my pressure readings

Pump 360
Pilot pressure 300
Gst 300
Clutch pack 100
Modulate valve 75
These are still with the traveler fluid, I haven’t got the udt yet.
I’m wondering with the udt fluid will I have more clutch pack pressure.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,676
5,106
113
Sandpoint, ID
I checked my pressure readings

Pump 360
Pilot pressure 300
Gst 300
Clutch pack 100
Modulate valve 75
These are still with the traveler fluid, I haven’t got the udt yet.
I’m wondering with the udt fluid will I have more clutch pack pressure.
It could, kind of hard to say!

Your numbers are off on Pilot pressure and GST that's not normal, they need to be the same as pump pressure.

Those being low will affect every other number on down the line.

Change fluid and filter, and recheck numbers, if they are still off your going to have to work on the system one part at a time.
 

Bryson Lamboy

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Dec 30, 2019
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I replaced filter and fluid with Kubota products and still no difference in fluid pressure.

I'm not sure what direction the fluid flows in the gst valve assembly from the pump. If anyone has a diagram, that would help. Thanks
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,676
5,106
113
Sandpoint, ID
I replaced filter and fluid with Kubota products and still no difference in fluid pressure.

I'm not sure what direction the fluid flows in the gst valve assembly from the pump. If anyone has a diagram, that would help. Thanks
The fluid path diagram is in the WSM, along with all the points to check it and one by one ways to set each pressure area.

It's a pretty detailed troubleshooting checklist, are you not reading and following the checklist to isolate the problem?

I asked once before but would like to make sure we are perfectly clear on , did you change the entire clutch pack out with a new pack, that would be all the clutch plates, housing, piston, piston seals inside and out and housing seals?
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,842
1,595
113
Mid, South, USA
leak in clutch pack or leak between the clutch pack holder assembly or sealing rings leaking are my best guesses.

Could also be an issue with the valve body but I'm guessing leak at the clutch area.
 

Bryson Lamboy

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Dec 30, 2019
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CAVE SPRING
Yes I replaced with a new pack and all seals. I tested the clutch pack by blowing air into the port and I can see the pack engage and release when air is applied. I'm thinking the clutch pack is okay and i am not getting enough pressure to and through the valve assembly.

I do not have a service manual to follow the steps.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,676
5,106
113
Sandpoint, ID
I thought you already had the WSM. :eek:

Well we can fix that, check your PM. ;)