Well, it seems that my front loader has almost the same symptoms as RWolf's. I have a Kubota L3010 with a 481 loader, with 440 hours. Last fall I noticed that the bucket breakout power seemed like it was not as good as it always used to be, but I really didn't give it too much thought. I installed my Kubota factory snow blade this winter (1st year with it), and this thing really kicks ***. It worked great pushing mounds of snow, and when the frost cleared out I used it to clear a 100 ft. long extra driveway through the woods, just blasting throughthe dirt like a dozer- it really is remarkable! Last weekend I reinstalled my loader to start moving gravel for my driveway and noticed immediately that when digging into a pile of gravel there just didn't seem to be a lot of power for lifting and curling. The other problem I noticed was with the bucket at half dump and the loader raised, and then being lowered to " rake" some of the material off the top of the pile, the bucket would actually "curl" back under the pressure and then flop down to full dump when the material fell away.( I hope that makes sense). I can also only raise a full bucket to hood height, and very slowly at that. Last night I changed the hydraulic fluid, filters, and cleaned the suction screen with no improvement. There weren't any particles on the suction screen, and just a few tiny shavings on the filter magnet. This weekend I will be putting a pressure guage on each of the loader control valve outlets, ( one at a time), to check the pressures. I think Kubota lists the pump pressure at 2500 psi. If the pressure isn't up to par, where is the relief valve that can be shimmed, and is that the right fix?
Another weak front loader
- Thread starter ELMO67
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Soundguy
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If the pressure is nor up to par .. make sure it is not a bypassing cyl or valve before you go dinking with any reliefs..
I'd check to see if the cyl's are bypassing internally. remove the dump line front he bucket cyl, and then curl it under pressure to limit, and hold it there.. if oil shoots out the dump port.. the cyl is bypassing...
soundguy
I'd check to see if the cyl's are bypassing internally. remove the dump line front he bucket cyl, and then curl it under pressure to limit, and hold it there.. if oil shoots out the dump port.. the cyl is bypassing...
soundguy
slowzuki
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9/10 times says you have a faulty loader quick connect. Unplug them all and replug in.
That sounds like my kind of fix! When I reinstalled the loader last weekend, I had a lot of trouble getting the coupler to connect for the curl cylinder (4 new couplers and hoses to the control valve). I tried to compress the center nipple ( very difficult) and when I did fluid shot out all over. I tried to reconnect and still couldn't, and at that point I could not depress the center nipple at all. I loosened the hose connection at the cylinder and bled out most of the fluid and the coupler went right on... I can't wait to get home and check that!!! Funny thing is on Sunday I mentioned to my brother-in-law the PIA I had hooking up the loader and he said " Just depressing the center nipple shouldn't be a problem".
Wayne County Hose
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Soundguy said:
Nice easy test. Even if the oil weeps out, the piston seals are bad. Let's see, 4 new hoses, probably not cleaned before install, and now a FEL issue, hmmm..........
I did blow out the hoses... I really think the problem was starting last summer as I mentioned, but it does seem a lot worse this year. Well, if this is the case, would that mean a complete rebuild of all four cylinders?
Wayne County Hose
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If it started last summer and progressively got worse, I put my money on worn piston seals. Valves usually work or they don't. Do the test Soundguy pointed out.
Oh, and please just trust me on this, but blown out is not cleaned out. It's kind of like getting mud on your blue jeans and letting it dry. Blow the mud off with air, a lot of the mud is gone, but they're still dirty.
Oh, and please just trust me on this, but blown out is not cleaned out. It's kind of like getting mud on your blue jeans and letting it dry. Blow the mud off with air, a lot of the mud is gone, but they're still dirty.
Oh, I believe you 110%, anything I've ever painted- cars, furniture, models, etc. or any engine or tranny I've built has to be surgically clean. I know better than to try and get by just blowing the lines out but I guess I'm just trying to console myself for my stupidity this time. I really don't think it is the valve since the plow had so much power. But still, if the pressure test reveals that it could be a relief problem, where would the relief valve be on my L3010?
PAB_OH
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ELMO67 said:
Air in the circuit?
Soundguy
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ELMO67 said:
I wouldn't even worry about finding the relief till I did the leak-by test ont he cyl's. might be a simple case of new packing is all you need..
soundguy
Well, last night I tried the leak test on all four cylinders and there wasn't a bit of seepage from any of them. I also disconnected and reconnected all the q/d couplers, still no change. I filled the bucket as much as possible, raised it up as far as it would go (hood height), and let it sit for about 20 minutes- didn't drop an inch. I guess my next check will be a pressure test at the control valve ports. I found my Kubota parts book and it shows the relief valve at the hydraulic block under the right side of the floor with the control valve feed and return hoses hooked to it.
Wayne County Hose
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Can you post the hydraulic schematic.
slowzuki
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Ok hearing this now, you will really need to make up a pressure gage with a tee and male and female q/c's on it to diagnose.
The slow raising and both curl and boom circuits being affected at the same time points to it not being a blown packing.
It does sound like there is a pile of air in your cylinders too. If you raise the loader and hop on it, does it bounce? Still should raise all the way though.
Post up what your pressure gage shows on each circuits lines.
The slow raising and both curl and boom circuits being affected at the same time points to it not being a blown packing.
It does sound like there is a pile of air in your cylinders too. If you raise the loader and hop on it, does it bounce? Still should raise all the way though.
Post up what your pressure gage shows on each circuits lines.
The bucket will raise fully and curl/ dump fully when empty, but it will only raise about half way full- but very slowly- and I'm not able to bounce it at all. Don't I need to deadhead the pressure guage and not "T" it in?
Wayne County Hose
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Bear with me because I do not know your mechanical ability.
First thing you have to do is pressure test the pump. Nothing else matters in your hydraulics if your pump is not putting out the pressure in needs to. If you don't have a pressure gauge, you will need one. Let me know if you need a parts list for a gauge kit. I can give you a list of fittings that should cost under a hundred bucks, gauge included.
Your problem has nothing to do with air in the lines. See if you can post the hydraulic schematic.
First thing you have to do is pressure test the pump. Nothing else matters in your hydraulics if your pump is not putting out the pressure in needs to. If you don't have a pressure gauge, you will need one. Let me know if you need a parts list for a gauge kit. I can give you a list of fittings that should cost under a hundred bucks, gauge included.
Your problem has nothing to do with air in the lines. See if you can post the hydraulic schematic.
slowzuki
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If its a simple pump problem yup he will need to deadhead the pump with the gauge in circuit. If its not he's gonna have to read pressures on the different circuits.
I asked about bounce because often when people get air in the boom circuit they think they can't lift a full bucket because they don't wait long enough to compress the air. I should have caught that he got it mid way up.
If pressure is getting to both sides of his boom pistons this certainly will cut his loader lift to about 1/6 of original as the area of the shaft will be the only piston the fluid is pushing on. This is where the gage in the circuit will tell you whats happening on the back side of the ram.
If his valve is working right, he likely does have a pump problem, but given the blade and low hours that isn't likely. I agree a diagram would be nice.
I asked about bounce because often when people get air in the boom circuit they think they can't lift a full bucket because they don't wait long enough to compress the air. I should have caught that he got it mid way up.
If pressure is getting to both sides of his boom pistons this certainly will cut his loader lift to about 1/6 of original as the area of the shaft will be the only piston the fluid is pushing on. This is where the gage in the circuit will tell you whats happening on the back side of the ram.
If his valve is working right, he likely does have a pump problem, but given the blade and low hours that isn't likely. I agree a diagram would be nice.
Wayne County Hose said:
It goes pump, FEL (no relief in the fel controls), relief valve, 3pt then sump.
The relief block under the operators right foot that has the hoses connected to it has a large "bolt" going vertically up on the right side of it as you face it. Spray it off with brake clean, dry it then take that out. You will probably get the bolt, o-ring, spring and shims but not the poppet or valve seat. The shims are under the spring. You won't lose much fluid so no need for panic speed. Kubota sells them in 0.1, 0.2 and 0.4 mm thickness. every 0.1mm is 38.4 psi increase (approx).
Kubota 31351-37960 SHIM 0.2
Kubota 31351-37950 SHIM 0.4
Kubota 31351-37970 SHIM 0.1
Test the pressure before you add shims and after, then double check a week later. I like to target the high spec or just over as the spring will weaken with time. Pressure spec is 2347 to 2489psi.
