Hydraulic Pump Problems

[ct18fireman]

I have an 1982 L245DT with a Kubota front loader plumbed into hydraulic system. While operating loader last week I blew return hose from loader valve. Immediately shut down tractor. Got a new hose and checked fluid almost no lost. Tractor sat for a couple days before new hose attached today. Hydraulics were very sluggish and eventually worsened. At this point even at full throttle tractor will not lift 3pt arms with me (200lbs) standing on them and will not lift loader or curl bucket.

Fluid is moving, loader cylinders move until slack in pins is taken up then nothing. Fluid level in transmission is fine and I figure I will change filter. Am I missing something obvious or is the pump gone?

 

[freewheel3]

Possibly the pump is gone but it sounds like it was putting out enough pressure to blow a hose. Maybe its simply an airlock? It should self prime but maybe try loosening a fitting on the loader and then applying hydraulic pressure to that fitting and see if any air comes out. You might have to run a gallon or so through it to make sure there is no air in the system.

 

[Big Kahuna]

Air, just keep working the system under idle or 1/4 throttle and all will be fine, do not crack lines open, you can make it worse.

Big Kahuna

 

[kubotasam]

Does the return hose from the loader go to the hydraulic oil sump in the transmission/differential or is it plumed in series with the 3 point hitch control valve? If it goes straight to the transmission there should not be any pressure to "blow the return hose". My guess is that it goes to the 3 point hitch valve and you have a problem with the 3 point control valve and/or the built in relief valve.
What were you doing when the return hose failed? If you were lifting the 3 point then I think you should look at the 3 point control.

 

[ct18fireman]

Let me rephrase. A very old line (hose) cracked and sprayed fluid all over. A time it broke loader and 3 pt were working fine.

Pressure and return from loader go to a block on top of transmission where pressure line come from pump.

 

[Bulldog]

I wouldn't think it's the pump going out, it just sounds like air to me. I have seen it take 10 or 15 minutes of run time (low idle) before the air would work itself out of the system. Let it run and cycle thru the loader functions, if it's air it should start to improve pretty quick.

 

[ct18fireman]

OK After having sat for about 4 hours I just had it running for about 30 minutes. Still not making pressure. I can see that fluid is moving through transmission from looking at fill port. Fluid does look a little milky (maybe foamy?) compared to new that I added. I let it run at idle and moved the levers, still just getting movement of cylinder until it hits load, then nothing, no sense of load on engine, no movement in hoses from pressure, no squealing or bogging down nothing. I do have a hydraulic pressure gauge but not hooked up. It has a two lever loader valve. Had to shut off because it was getting late.

I have done hydro work on other things before, such as replacing pumps on my ZTR mowers. Jack up the wheels run on idle for 10-15 minutes to work air out. Wheel spins faster and faster. Doesn't seem to be working in this case with the loader.

 

[North Idaho Wolfman]

You said it's piped into the main hydraulic system, does the 3 point work right?

 

[Bulldog]

Milky fluid sounds like it's sucking air. Have you checked the rubber suction hose on the input side of the hyd pump? They are bad to crack and for whatever reason they almost always seem to crack to the inside where it's all but imposible to see.

 

[ct18fireman]

Still no progress on this. Tractor has run at idle for long periods of time, with levers moved and without. Still not building pressure. Three point hitch will not lift me!

I guess tomorrow I will get a coupler and tie the two hoses together bypassing the loader valve and see if I get three point. Checked the rubber suction hose, no cracks. Its moving fluid but not building pressure.

 

[North Idaho Wolfman]

Yes if the 3 point isn't working also then I would say it's possible that the pump took a dive.
But I would change the filter and check the screen first just to be sure that it didn't shove something into them.

 

[ct18fireman]

Got a fitting today so that I can tie the two lines going up to the loader together and bypass the loader valve. I also got an adapter so I can check pressure on the line. I don't see a pressure test port on the pump or lines. Have not tested anything yet. I have changed screen filter by rear end it looked clean. Going to see if I bypass loader if I get 3pt lift.

Pictures as follows of the block where, line diverts into loader valve. Is there any kind of bypass here?

Next picture is the loader valve I have. Pressure in and out are disconnected at this point. Return on right is where line broke. It has a relief valve at the in port

Final picture is on drivers side right below seat. Is this the main relief valve? This would not have anything to do with loader though right?

 

[ct18fireman]

Hooked lines together, fired up and 3pt lifted me and my brother right up and just off idle, before it wouldn't even lift me. So it would seem the pump is fine. Looking like something in valve even though it doesn't make sense to me how it could be losing pressure in the valve body without fluid spraying out of it. Tomorrow going to hook valve back up to see if there are any changes, then I know someone with a similar tractor maybe I can borrow their valve to test.