BX2380 hydraulics still leaking

Russell King

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Jun 17, 2012
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@Bruh44
There is a great variety of threads used in hydraulic systems.
Japan uses metric types that usually have a JIS (Japanese Industrial Standard) but they also use a style that is from other countries like the BSP (British).

America uses JIC (Joint Industry Council) and SAE (Society Automotive Engineers) and also NPT (National Pipe Thread). And there are others.

The NPT and BSP both have straight thread and tapered thread versions to make it even more difficult.

The JIC is used to seal hydraulic hoses in the USA since they are easy to get swivel fittings so the hoses don’t have to be rotated to tighten up the thread. This system is also confusing since there are 37 degree angles on the ends that seal in this system but SAE uses 45 degrees

The naked eye is not a reliable way to see what systems are involved. Knowing the tractor was made in Japan but the loader may have been made in the USA also does not make it any easier.

The only reliable method is to get a hydraulic thread measuring system and then learn to use it. Like this

Or you can make educated guesses using the diameters only and fittings that you know were in the female thread before.

In my limited experience too many of the sizes are too close together and the threads on various fittings will start into the female thread and seem to be working but do NOT really seal. For instance if you get straight NPT fitting it will screw into a tapered NPT hole but will never seal at hydraulic pressure. NPT is used in many places but really needs to be avoided as much as possible. Most common couplers come with NPT tapered threads though.

I suggest that you probably have some fitting with NPT threaded into a hole with a different type of thread and it will never stop leaking. It may have been delivered to you with the wrong fitting installed.

I also suggest that you know what threads are in what part before you install anything again. You may be able to take the hoses and the couplers to a hydraulic supply shop and have them identify those threads. They can then sell you the proper fitting and seal for the thread if needed. They may be able to assemble and test it for leaks.

Alteratively get the thread gauge and identify the fittings that leak and get new parts which match.

That is a much longer description of what @TheOldHokie said already.

I personally just installed several hydraulic hoses and fittings (some were tapered NPT) and none are leaking. I knew what the threads were in each part and got adapters as needed. Nothing had to be tightened up exceptionally tight. I did use Teflon tape (higher quality brand) and snugged the 1/4 NPT up pretty well using normal hand tool wrenches.

Sort of interesting while trying to positively identify the thread into the coupler I was pretty sure it was 1/4 inch NPT so used a street elbow to check. That elbow would start but not make a turn or two before it was too tight. That made me think it was NOT what I had assumed. I then got a better quality brass fitting and it screwed in perfectly with 1/4 inch NPT thread. The street elbow had damaged threads and was trying to steer me wrong but the measurements on the coupler threads were still telling me that it was 1/4 NPT and a better fitting proved it.

Good luck on this!

EDIT: eliminated my confusing statement on JIC angle
 
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TheOldHokie

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@Bruh44
There is a great variety of threads used in hydraulic systems.
Japan uses metric types that usually have a JIS (Japanese Industrial Standard) but they also use a style that is from other countries like the BSP (British).

America uses JIC (Joint Industry Council) and SAE (Society Automotive Engineers) and also NPT (National Pipe Thread). And there are others.

The NPT and BSP both have straight thread and tapered thread versions to make it even more difficult.

The JIC is used to seal hydraulic hoses in the USA since they are easy to get swivel fittings for so the hoses don’t have to be rotated to tighten up the thread. This system is also confusing since there are 37 or 45 degree angles on the ends that seal in different system.

The naked eye is not a reliable way to see what systems are involved. Knowing the tractor was made in Japan but the loader may have been made in the USA also does not make it any easier.

The only reliable method is to get a hydraulic thread measuring system and then learn to use it. Like this

Or you can make educated guesses using the diameters only and fittings that you know were in the female thread before.

In my limited experience too many of the sizes are too close together and the threads on various fittings will start into the female thread and seem to be working but do NOT really seal. For instance if you get straight NPT fitting it will screw into a tapered NPT hole but will never seal at hydraulic pressure. NPT is used in many places but really needs to be avoided as much as possible. Most common couplers unfurl come with NPT tapered threads though.

I suggest that you probably have some fitting with NPT threaded into a hole with a different type of thread and it will never stop leaking. It may have been delivered to you with the wrong fitting installed.

I also suggest that you know what threads are in what part before you install anything again. You may be able to take the hoses and the couplers to a hydraulic supply shop and have them identify those threads. They can then sell you the proper fitting and seal for the thread if needed. They may be able to assemble and test it for leaks.

Alteratively get the thread gauge and identify the fittings that leak and get new parts which match.

That is a much longer description of what @TheOldHokie said already.

I personally just installed several hydraulic hoses and fittings (some were tapered NPT) and none are leaking. I knew what the threads were in each part and got adapters as needed. Nothing had to be tightened up exceptionally tight. I did use Teflon tape (higher quality brand) and snugged the 1/4 NPT up pretty well using normal hand tool wrenches.

Sort of interesting while trying to positively identify the thread into the coupler I was pretty sure it was 1/4 inch NPT so used a street elbow to check. That elbow would start but not make a turn or two before it was too tight. That made me think it was NOT what I had assumed. I then got a better quality brass fitting and it screwed in perfectly with 1/4 inch NPT thread. The street elbow had damaged threads and was trying to steer me wrong but the measurements on the coupler threads were still telling me that it was 1/4 NPT and a better fitting proved it.

Good luck on this!
Thread standards are very complex. Please be careful with assertions.

For example:
  1. Both BSP, NPT, and ISO standards provide for the use of tapered male fittings in the corresponding straight thread female port but not the other way around. in BSP/ISO this is designated as Rc/Rp and in NPT as NPTF/NPSF. A real world example is the current generation of Kubota hydraulic diverter blocks. The female thread is NPSF and the male fitting is NPTF.
  2. There is no JIC fitting that uses a 45 degree seat angle. JIC is always 37 degree. SAE fittings have a 45 degree seat angle. JIC and SAE fittings are not compatible BUT dash sizes 02, 03, 04, 05, 06, 08, and 10 use the same threads and you can find special hybrid fittings that have dual angle 45/37 degree seats. These hybrids are compatible with both SAE and JIC fittings.
Dan
 
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Bruh44

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BX2380
Mar 29, 2023
60
10
8
North Carolina
Would you all recommend thread dope for the taped fitting? A gasket or O ring maybe? I’ve read in a number of places now that the parts I have are exactly what I need. I’m hesitant to change anything out because this exact set up seems to work for some people. I’ll definitely clean it all up before reinstalling. I’d like to hear what you all have to say about the threat dope, gasket or o ring.
 

TheOldHokie

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Would you all recommend thread dope for the taped fitting? A gasket or O ring maybe? I’ve read in a number of places now that the parts I have are exactly what I need. I’m hesitant to change anything out because this exact set up seems to work for some people. I’ll definitely clean it all up before reinstalling. I’d like to hear what you all have to say about the threat dope, gasket or o ring.
For pressure tight joints tapered pipe fittings require the use of a thread sealant. Technically NPTF (aka DrySeal) tapered pipe threads do not but good luck with that.

Dan
 

Jim L.

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Jun 18, 2014
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Texas
Have you looked at Loctite 545? Cures with metal contact and holds up to 10000 psi. Surfaces must be cleaned before application since metal ions are what cures it.
 
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TheOldHokie

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View attachment 106456 This is what I put on it. There are two connections that just screw together in the circled part. One of them, possibly both are leaking on all for lines.
What is the full part number stamped on the female quick coupler in your picture?

Dan

D9B5BE9E-6B9C-4F94-96F1-883A306F76EA.jpeg
 
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dieselbob69

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Kubota BX2380 (previously a BX1870 and GR2100)...
Jan 2, 2022
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WNY
Do you have any hydraulic hose dealers near you? Take the old hoses and ends with you and tell them what you want to go to....I'm lucky and have one 6 miles from me. Even if you have a dealer they probably can get you set up with what you want, I'm sure they've had people wanting to delete that loader quick coupler with regular connections...
 

TheOldHokie

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Sorry, it’s this:
FF14F-04N
1/4" Flat Face Hydraulic Quick Connect Female Coupler, 1/4" NPT Thread
That should seal fine with your Weatherhead adapter. It does require a thread sealant on the NPT threads but not on the JIC end.

Dan
 
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Bruh44

Member

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BX2380
Mar 29, 2023
60
10
8
North Carolina
I got it mostly fixed. I’m down to one leak. I’ll get on that this weekend.
I did pull all the lines off and brought them to a hydraulic shop. Do I need to bleed the lines out now? If so, where are there bleed valves on a BX2380 loader?
 

Russell King

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Jun 17, 2012
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No need to bleed anything. Just install the new hose and then cycle the cylinder fully both ways several times.
 

Russell King

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Jun 17, 2012
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Austin, Texas
The cylinders are what move and curl the bucket on the front end loader.

just lift and lower the front end loader several times and then curl bucket up and down several times while doing the up and down.

ignore below if you don’t want to read a more detailed description of what happens!

The system is open center which means that the pump pushes fluid through all valves and then to the transmission sump. When you activate the valve by pushing or pulling the lever the fluid is diverted into the hose or into a cylinder. On the loader are several cylinders that are double acting (two hoses attached and pressurized fluid at one end moves the piston and rod). These cylinders and hoses can have air in them but when you force fluid into the hose the air mov into the cylinder and the piston will be pushed by the air and fluid in the cylinder. That will force most of the fluid and air out of the other side of the cylinder. That fluid returns to the valve and then to the transmission sump through the low pressure tank return line. The back and forth between up and down will eventually displace the air from both sides of the cylinder.