M6060 low hydraulic pressure

[rowsley]

I have a m6060 with 800hrs, new filters and fluid new loader cables. I first notice the loader seemed a little week at times, then I got a 10' pull type brush hog last spring. The tractor would only lift the brush hog at half throttle or better. Figured it was just heavy

In the middle of last summer I bought/ made a grapple bucket with a foot mounted control valve. All worked find for about an hour. While using the brush hog I tried to pick up a small round bale and notice the loader lifting very slow! When I got back to the shop I removed the front remotes and foot valve from the system,

No help, took both pressure relief and rear safety valves apart, all looked good. Remove rear remotes to check for stuck valves. Still had not found the problem. Took the pump apart, Looked like new!

With a pressure gauge hook up to the fel the pressure will hit 2700 psi for a split second then drop to 1500 psi. At the rear remotes 500 psi is the best it will do dead headed. Power steering works good. I know it is bypassing somewhere just have not found it yet. Going to pull the loader valve apart next!

I removed the 3pt arms because they hit the brush hog, So I could not tell you if it is week as well.

I found a kubota facebook group that had a post by a kubota tech with a new m6060 and a loader that would not lift. I'm not on fb anymore so don't know if he fixed it.

 

[TheOldHokie]

With a pressure gauge hook up to the fel the pressure will hit 2700 psi for a split second then drop to 1500 psi. At the rear remotes 500 psi is the best it will do dead headed. Power steering works good. I know it is bypassing somewhere just have not found it yet. Going to pull the loader valve apart next!

Wher did you connect the gauge to the loader - one of the cylinder ports? This is an open center system so if the loader is not getting pressure the problem is in or before the loader. You can check pump outlet pressure directly by connecting a gaige to the hydraulic outlet as shown below.

*** WARNING *** - THERE IS NO RELIEF IN THAT CIRCUIT - FOLLOW THESE INSTRCTIONS EXACTLY

Connect a tee to that outlet and install the gauge in the middle leg. Connect a hose and needle valve to the other leg and run the circuit back to the tank fill port.

FULLY OPEN THE NEEDLE VALVE

With the valve fully open you can now start the tractor. Once the tractor is running you can slowly close the needle valve to bring the pressure reading up.

DO NOT CLOSE THE VALVE ALL THE WAY WITHTHE TRACTOR RUNNING

That will deadhead the pump and destroy it. You should be able to get full system pressure with the valve partially closed. If not the pump is not working.

Dan

 

[rowsley]

Thanks for the info. Yes I have the gauge hooked to the cylinder port. I do have a shop manual with a flow chart that explains the same procedure.

You are right I need to separate the pump from the rest of the system. But I really don't think the pump would produce 2700 psi at all if it was damaged. The pump had no internal damage when i took it apart.

What I do not have is an exploded view of the loader control valve . That would be very helpful if anybody has it or could point me in the right direction.

 

[TheOldHokie]

Thanks for the info. Yes I have the gauge hooked to the cylinder port. I do have a shop manual with a flow chart that explains the same procedure.

You are right I need to separate the pump from the rest of the system. But I really don't think the pump would produce 2700 psi at all if it was damaged. The pump had no internal damage when i took it apart.

What I do not have is an exploded view of the loader control valve . That would be very helpful if anybody has it or could point me in the right direction.

The initial spike can he deceiving. But assuming the pump is producing a continuous 2700 PSI inlet pressure and you get less than that at the cylinder port your loader valve is bypassing. You dont need a parts diagram to know that.

The loader valve almost certainly has an inlet pressure relief valve. Most likely a screw in cartridge. That would be first on my list of suspects.

Edit:

Edit:

I am assuming you have the LA1154 loader. It came standard with the valve shown below. The self leveling valve was available as an option and is a lot more complex. Nothing in this diagram jumps out to me as a relief valve. Item 120 is described as "valve" but it looks like a load check to me. However quantity list says one but the diagram shows it going into two ports and quantity for oring 130 is two so something is clearly wrong. I am betting its a load check, there are two of them, and the pressure relief is somewhere else in the system.

Edit2:

Damn Kubota documentation sucks. Here is the parts diagram for the hoses. The item circled in red sure as hell looks like a relief cartridge/valve of some sort.

Dan

 

[rowsley]

Yep you are right LA1154 and that is an adjustable pressure relief valve. That was one of the first things i checked, even switched with the one on the 3 point. Both where clean and seated. Tried adjusting with no luck. At first I thought I would find some trash stuck in a relief valve from installing the control valve and hoses to the front for the grapple bucket.

Thanks for the diagrams!

I'm sure glad I didn't sell my 3830! But then I would have fixed the 6060 a lot sooner!

 

[TheOldHokie]

Yep you are right LA1154 and that is an adjustable pressure relief valve. That was one of the first things i checked, even switched with the one on the 3 point. Both where clean and seated. Tried adjusting with no luck. At first I thought I would find some trash stuck in a relief valve from installing the control valve and hoses to the front for the grapple bucket.

Thanks for the diagrams!

I'm sure glad I didn't sell my 3830! But then I would have fixed the 6060 a lot sooner!

The loader valve is fed directly from the pump. If you dont get pressure at the cylinder port and the inlet relief on the loader valve is working that does not leave a lot of possibilities. It points straight to the pump. Pressure test it directly and you will know for sure.

Dan

 

[rowsley]

I was thanking that very same thing!
I finally got a chance to look at the 6060 sunday afternoon. i did have the gauge hooked to the pressure hose coming from the pump. I will rig up a valve this week.

 

[rowsley]

Has it been a week yet! (It is the pump). Put a valve in line between pump and by hose, closed the valve completely pressure spiked then dropped with out changing the rpm's. Will pull the pump back apart soon.

I see pump prices very from $470 to $1250.

 

[JP_Austin]

Did you eliminate the simple things like enough hydraulic oil in the system?

... Ahh I re-read the first post and I did see where you changed the filter and put in new oil. Does sound a bit like the pump

 

[rowsley]

new pump fixed the problem! ordered 1 for $470 then a buddy found 1 for $195 on amazon. they both look just like the kabota pump minus the part # ! good to have a spare on the shelf.