M6800 hydraulics overheating

   / M6800 hydraulics overheating #11  
You need to install a hydraulic oil temp gauge. "Too hot to hold" is not an accurate reading. Your o-rings and seals are rated to 212 degrees. If you're running at 180 you are still 32 degrees below max but still too hot to hold. It does sound like you are working the snot out of this tractor. I'm not familiar with your model so I don't know if it's a homeowner model or industrial model. BTW, there is a big difference between the two.

Andy
 
   / M6800 hydraulics overheating
  • Thread Starter
#12  
I checked hydraulics again this evening with the tractor cold. The gauge would go all the way to ~2700 psi then it would fluctuate between ~1000 psi and ~2700 psi. To check the hydraulics I insert a QA into one of the rear remotes and set the engine to maximum speed (it recommends that the fluid temperature be between 113-131 degrees F). Then I engage the remote lever and read the pressure gauge when the relief valve is actuated. Could the relief valve be malfunctioning?
 
   / M6800 hydraulics overheating #13  
If the pressure reliefs are working, then the pressure should be good, because they only relieve at the set pressure. Is it relieving at 2700 psi? If you are not working the system hard, the pressure will not stay high. With the tractor running, and no levers activated, there will be very low pressure. If you raise an empty bucket, you may see 500 to 1000 psi. If you have a full load, you may see 2500 psi. If you hold the levers full forward or full back, then the reliefs will go off, and you will read relief pressure. If the reliefs are being used a lot, then the fluid will get hot. If the relief valves fail closed, you could damage your pump. If the reliefs fail by staying open due to trash, you will have low pressure.
 
   / M6800 hydraulics overheating #14  
I just looked at the parts brake down for the high pressure lines and there is a coupler just down stream from your pump.Check and see if you can Tee there so you can put the gauge there it well tell you more. Up to 2700psi and down to 1000psi seem like alot of differents. I would check the steel HP line and make sure its not smashed. If not pull the main relief and have a look, also while there put a new spring in it if your dealer has one.
 
   / M6800 hydraulics overheating #15  
   / M6800 hydraulics overheating
  • Thread Starter
#16  
Noticed yesterday that detent on rear hydraulics won't kick out now. Also it sounds like the hydraulic pump is starving for fluid because now it's whining when FEL cylinders reach end of their cycle and when the rear hydraulics are in the detent position.
 
   / M6800 hydraulics overheating #17  
Noticed yesterday that detent on rear hydraulics won't kick out now. Also it sounds like the hydraulic pump is starving for fluid because now it's whining when FEL cylinders reach end of their cycle and when the rear hydraulics are in the detent position.

That sound you hear when the cylinders are at their limit, is the relief valve going off, and the pump is working hard. If you put a pressure gage on the cylinder hose, you can see the pressure in the operating mode, and then you will see the relief pressure when you hear the sound at the cylinder limit. The pressure you see on the cylinder gage will vary by the load in the bucket. An empty bucket being raised, may only show about 500 lbs, but as soon as you hit the limit, you will see relief pressure. Rules are rules.

What are you using on the back, that requires the valve to be in detent mode? If you are using the PB port on the FEL. and you set the rear valve to detent, the fluid is going through the FEL valve, back to the rear, but as soon as you activate a lever on the FEL, it interrupts the fluid going to the back, because it has priority and uses it for the FEL. This is assuming that you are using the PB port. A detent valve lever, should not come out of detent until you manually move it, except on log splitter valves , which are automatic.
 
   / M6800 hydraulics overheating
  • Thread Starter
#18  
Finally solved problem! Pulled hydraulic pump and one set of the gears were seized up. Have no idea how this could have happened. New pump on the way.
 
   / M6800 hydraulics overheating #19  
My 09 m6800, 4x4, factory loader, hydraulics overheated today, using15' bushwacker batwing, grass fence high, ran in 1st, max rpm, 4hrs, notice heat, got a little hard to stear, shut down, back of tractor to hot, could here fluid boiling, Do I need to clean radiator, changeengineoil and HUD fluid? Is tractor supply fluids as good as kubota's? Thanks Bo
 
   / M6800 hydraulics overheating #20  
I would start a new thread with your question. But if you literally boiled the fluid, I would change it and your filters and find out why it got that hot. CJ
 

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