Non-functioning hydraulics

[Dashman]

I have a Kubota L4300DT with an LB552 FEL controlled by a HUSCO 9210 control valve. A few years ago, I installed remote hydraulic lines and a controller. Last year, I had fluid leaks at the quick disconnects and I needed to replace the lift spool float detent mechanism. I also had a transmission shift stick boot deteriorate and got some water into the fluid. I rebuilt the control valve, drained the hydraulic fluid from (4) places, installed the control valve, replaced the filter, filled with fluid, and I started the tractor to flush some fluid from the PB circuit prior to the remote valve. I've kept the fluid level in the sight plug.

When I re-installed the PB hose to the remote controller and re-started the tractor, I didn't have hydraulic pressure to the FEL nor the 3 point hitch.

I tried pushing air into the rear fill hole, and pushing oil into the outlet/inlet hose to the FEL control valve. On the hydraulic block left to right the ports are: inlet, outlet, and tank. That hose from the outlet port on the block goes to the inlet of the FEL control valve. Correct?

I cracked the PB hose just to see if fluid would leak, and sure enough it did. I cracked the filter, and sure enough fluid leaked there too. I don't hear any whine from the pump, and the steering works fine. I can't move the tractor because the FEL is down. What am I missing? Thank you.

 

[Russell King]

The FEL is normally first in line so the flow is this:
Tractor pump out to FEL valve inlet then out the Power Beyond (PB) of the FEL into the rear remote power in port. Then out of that valve PB port and to the 3PH valve. That last connection is often a hose back to the tractor near where the hydraulics flow came out.

From the operating manual for your tractor on page 37 there is also a manual selector that must be in the correct position. That is most likely the problem.

 

[Dashman]

Thank you for your response Russell!

I have both the tractor and loader manuals. I followed the loader manual extensively when I added the remote control valve. Today I rotated the "control screw" horizontal and back to vertical while the tractor was on with no change.

Tomorrow I'm going to go one step further, and remove the outlet hose from the remote control valve to make sure I'm getting flow through that control valve to the hydraulic block.

 

[North Idaho Wolfman]

I have a Kubota L4300DT with an LB552 FEL controlled by a HUSCO 9210 control valve. A few years ago, I installed remote hydraulic lines and a controller. Last year, I had fluid leaks at the quick disconnects and I needed to replace the lift spool float detent mechanism. I also had a transmission shift stick boot deteriorate and got some water into the fluid. I rebuilt the control valve, drained the hydraulic fluid from (4) places, installed the control valve, replaced the filter, filled with fluid, and I started the tractor to flush some fluid from the PB circuit prior to the remote valve. I've kept the fluid level in the sight plug.

When I re-installed the PB hose to the remote controller and re-started the tractor, I didn't have hydraulic pressure to the FEL nor the 3 point hitch.

I tried pushing air into the rear fill hole, and pushing oil into the outlet/inlet hose to the FEL control valve. On the hydraulic block left to right the ports are: inlet, outlet, and tank. That hose from the outlet port on the block goes to the inlet of the FEL control valve. Correct?

I cracked the PB hose just to see if fluid would leak, and sure enough it did. I cracked the filter, and sure enough fluid leaked there too. I don't hear any whine from the pump, and the steering works fine. I can't move the tractor because the FEL is down. What am I missing? Thank you.

It sounds like you have swapped the PB and tank lines.

 

[Dashman]

I thought that might be a possibility, so I checked the Prince MB single spool port descriptions. I have the PB from the FEL control valve into the inlet of the remote valve. The outlet is on the opposite side of the valve, and that is routed to a tee to the tank port on the hydraulic block. The PB of the remote valve is just above that, and is routed to the inlet port of the hydraulic block. I sketched it out, and seems correct. Let me know, if I'm not.

Come to think of it, I had that inlet port fitting cracked to loosen one of the other hoses, and I didn't notice much fluid leaking from it. I'm going to fully remove it tomorrow and start the tractor. If fluid doesn't come out, I'm going to think that some water in the fluid that didn't drain has frozen in the remote valve.

If the remote valve is blocking flow to the 3 point hitch valve, then why doesn't the FEL work?

 

[North Idaho Wolfman]

I thought that might be a possibility, so I checked the Prince MB single spool port descriptions. I have the PB from the FEL control valve into the inlet of the remote valve. The outlet is on the opposite side of the valve, and that is routed to a tee to the tank port on the hydraulic block. The PB of the remote valve is just above that, and is routed to the inlet port of the hydraulic block. I sketched it out, and seems correct. Let me know, if I'm not.

Come to think of it, I had that inlet port fitting cracked to loosen one of the other hoses, and I didn't notice much fluid leaking from it. I'm going to fully remove it tomorrow and start the tractor. If fluid doesn't come out, I'm going to think that some water in the fluid that didn't drain has frozen in the remote valve.

If the remote valve is blocking flow to the 3 point hitch valve, then why doesn't the FEL work?

More likely water frozen in the filter or the suction side, than in a valve.

 

[Russell King]

Come to think of it, I had that inlet port fitting cracked to loosen one of the other hoses, and I didn't notice much fluid leaking from it. I'm going to fully remove it tomorrow and start the tractor. If fluid doesn't come out, I'm going to think that some water in the fluid that didn't drain has frozen in the remote valve.

But isn’t it above freezing now (and for a few days now)?

 

[Dashman]

Hello Russell and Wolfman,

Yes, it's been mid-60s for a few days here, but it does freeze at night.

I removed the PB hose to the inlet port on the hydraulic block, and there was flow with the tractor on. It wasn't a stream though. I caught about a quart in a few seconds. It wasn't milky, but it did have some micro bubbles.

Isn't there a regulator mounted on top of the pump on my L4300? Could I have affected something with the regulator that reduced the pressure?

 

[North Idaho Wolfman]

Hello Russell and Wolfman,

Yes, it's been mid-60s for a few days here, but it does freeze at night.

I removed the PB hose to the inlet port on the hydraulic block, and there was flow with the tractor on. It wasn't a stream though. I caught about a quart in a few seconds. It wasn't milky, but it did have some micro bubbles.

Isn't there a regulator mounted on top of the pump on my L4300? Could I have affected something with the regulator that reduced the pressure?

The output for the loader and three point section of the pump has no regulator only the PS section.
Loosen the output line at the block, and see what you get there.

 

[Dashman]

Today my 2nd new filter arrived, so I removed the 1st new filter and installed the 2nd. The oil that drained had some air bubbles and foam, not a lot but a little bit. I refilled about 2 quarts of the Shell Spirax S4 TXM hydraulic oil that I've been using. It's what was in it since 4 years ago. Still no functioning hydraulics.

I cracked the rear banjo bolt to the 3 point hydraulics about 1 turn, and it leaked. Then I started the tractor and it sprayed a bit. I shut it down in a couple of seconds. I cleaned around the area, tightened the banjo bolt, and restarted. Still no hydraulics.

I can't see any leaks and there's no abnormal sounds coming from the hydraulic pump. Is it time to check the outlet pressure? Would I put a line with a gauge on port "B" from the block?

 

[Russell King]

I don’t think you need to worry about pressure right now but if you want to you can. I believe you can get a gauge (with the proper range) and use one of the loader cylinder hoses and just put the gauge (on a disconnect half) and attach the gauge to the line and operate the valve to move that cylinder. Your loader valve MUST have a pressure relief valve in it to do the test in this way.

I would start your testing by removing the power in hose from the FEL valve so it is still connected to the tractor. Put the end into a clean 5 gallon bucket (so you can put the oil back into the tractor). Start your tractor and see if oil is pumped into the bucket. Don’t run it to long though or it will pump the sump dry of oil. Depending on how much oil is in the bucket, then put it back in the sump or wait until the second test is complete.

If you get oil then put the hose back, and move to the next valve and repeat the process (the PB line out of FEL valve should be the Pin of the next valve. Go to next Valve if you get flow.

Post the results.

If no flow in first test then you will need to figure out what is wrong with the pump.