Another weak front loader

[Soundguy]

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?

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

 

[ELMO67]

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]

Can you post the hydraulic schematic.

 

[ELMO67]

I don't have a scanner to scan my repair manual or parts book, but I'll try taking a digital photo and uploading it.

 

[slowzuki]

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.

 

[ELMO67]

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]

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.

 

[ELMO67]

Yeah, it should be pretty straight foward; guage, tee, m&f q/d plus appropriate fittings to tie everything together.

 

[slowzuki]

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.

 

[john_bud]

Can you post the hydraulic schematic.

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.