B8200 Hydraulic Failure

   / B8200 Hydraulic Failure #1  

mlmorton

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Aug 27, 2009
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4
I have a Kubota B8200 and the hydraulics started failing a couple weeks ago. They first got very slow and jerkey and then failed completely. I checked the fluid and it was a little milky so I changed it and cleaned the filter. No luck so I assumed the pump had failed - replaced the pump and no go - so I replaced the Pressure relief valve and no go. I am kind of at a loss at this point. I have a blade on the 3pt and a loader on the front and neither of them will operate. If I start the tractor and try to activate any of the hydraulics, it does nothing except occasionally (about every 15 seconds or so) I hear a grinding/vibrating sound that seems to be coming from the hydraulic block. The buket or 3pt will raise about a 1/4" when it makes the sound when the sound quits, the hydraulics doesn't move. Another 15 to 20 seconds and it will do it again. Could I have a failing control valve?

Stumped!!!
 
   / B8200 Hydraulic Failure #2  
Be sure the diverter handle is correctly positioned on your control valve - it will port the fluid to external cylinders (loader / backhoe) or back to the top cover. If it worked before, possibly the handle was moved slightly when you changed the oil. I

f you have no flow at all, then possibly you have an air lock on the suction side to the pump inlet. You may have to raise the rear of the tractor to get the fluid to flow to othe pump and then it should work again.

Good luck!
 
   / B8200 Hydraulic Failure
  • Thread Starter
#3  
Thanks for the reply. I have tried moving the flow valve both ways but no luck. I put the tractor on a steep hill with the front facing down so I am pretty sure it is getting fluid. When I take the input port bold loose on the pump, fluid comes out so I don't think it is air-locked.

Thanks!!
 
   / B8200 Hydraulic Failure #4  
Thanks for the reply. I have tried moving the flow valve both ways but no luck. I put the tractor on a steep hill with the front facing down so I am pretty sure it is getting fluid. When I take the input port bold loose on the pump, fluid comes out so I don't think it is air-locked.

Thanks!!

Do you have a hyd gage? If so, put it on the output of the pump, and connect a high pressure needle valve to the gage. You should have pump, gage, needle valve, and a short hose for putting into a clean bucket or back to tank. To determine fluid flow and pressure, start the tractor, and turn the needle valve down and see if you get any pressure. Do not crank it down all the way, or the pump may crack. You are looking for some pressure 1500 psi and above. If you have any kind of pressure, the pump is working enough to move a cylinder, etc. Next, put the gage in the cylinder circuit , and activate the lever for that cylinder, and see if you have pressure, and if so, does the relief valve come on.
 
   / B8200 Hydraulic Failure #5  
mlmorton,

A control valve fails by worn spools, or stuck spool, or leak externally, or connedted wrong. . If you have a supply of fluid coming to the control valve, in the neutral state, the fluid pases through the valve and back to tank. That same fluid could also pass through the PB port for valves in the back of the tractor, but only if the first valve is not activated. If you have a bad valve, nothing working internally, the fluid will just pass on through and return to tank. Did someone do any hose work on the valve lately, or any hydraulic work on the tractor?
 
   / B8200 Hydraulic Failure
  • Thread Starter
#6  
Thanks for the advise JJ. I do not have a pressure gauge but if I change the flow control valve and that does not work, then I will have to take it to a Kubota place and have them check the pressure. There has been no work done on the hydraulics prior to them failing a couple of weeks ago. I will pull the return line going back to the reservoir (Transmission) and see if I have flow. At least that will tell me if I have a blockage someplace in the system.

Thanks again for the advise!!!
 
   / B8200 Hydraulic Failure #7  
mlmorton,

Those 3000 psi pressure are real cheap from Surplus Hydraulics, plus a few fittings, an you will have a good idea what is going on with your hydraulics. The first thing a Kubota place is going to do is put a gage on it and check pressure. Those gages are around $15.00.
 
   / B8200 Hydraulic Failure #8  
I'm not familar with the noise, but do you think from the water that was in the system that it might have hurt the drive to the pump?
 
   / B8200 Hydraulic Failure
  • Thread Starter
#9  
Art, thanks for the reply. The fluid feeds directly to the pump from the transmission. The only thing in that line is a filter at the transmission end and I cleaned that when I changed the fluid. I have ordered a new filter and it will be in Monday along with a new flow control valve.
 
   / B8200 Hydraulic Failure #10  
I also am having the same problem with my Kubota b8200. it whines and grinds when the levers are activated. the bucket arm will raise, then stop and then raise some more. I just got done cleaning all the hydraulic parts and checking the O-rings. when I first started it the bucket moved very smooth and worked very well. then the whining and grinding came back. any suggestions on what I could check, I think it may be something small but just wondering, maybe someone has had the same problem and found the solution. thank you
 
 
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