3-Point Hitch MB265B 3 Point hitch will not raise

jhwentworth · Mar 15, 2009

stumpfield said:
Anyone know if the 3PH uses the same fluid as the rest of the hydraulic system. My loader, top and tilt all seem to work fine. I was able to raise the boxscraper about an inch off the ground to move the tractor using the top/tilt. Should I go ahead and change the hydraulic filter and fluid to see if it helps? Thanks.

FWIW: There's a block diagram of the hydraulic system in the service manual that shows the connections between system components. Considering the symptoms you described (tractor working properly, then a 1 week shut-down, now 3PH doesn't lift. All other hydraulics work OK) it doesn't seem likely that the problem is with the hydraulic power source. You mentioned a Top and Tilt; is this controlled by the auxiliary control valve? According to the block diagram the hydraulic pressure first goes through the auxiliary control valve before reaching the main control valve that operates the 3PH. Is this correct? If you raise the position lever and then move the auxiliary control valve is there any movement of the 3PH?

Are you able to manually lift the lift arms?

JerryG · Mar 16, 2009

You have one of two things wrong. A quick coupler isn't connected correctly. They can look like they are and not be. The other thing that it could be is one of your hydraulic levers. If one of the levers is not centering it can direct the flow so that the lift won't work. This can be the loader valve or the valve used for your T & T. Move these valves around and try the lift again. If this doesn't work, then take your quick couplers apart and reconnect them.

stumpfield · Mar 18, 2009

Yes. That's exactly the sympton. Top and Tilt is controlled by auxiliary control valve. After reading your post, I tried to raise the 3ph and move the Top/Tilt control at the same time. It works! Now I can raise and lower the 3ph with the position control lever. Not for long though

. I can raise it up and down just a few times then it stops working again. If I just move either the Top or Tilt lever back and forth just slightly, then I can raise the 3ph again. If I keep moving it up and down and it will continue to work for as long as I keep raise and lower in a regular interval. If I stop and let it sit in either up or down position for a minute or so, it stops working. What do you think is wrong?

jhwentworth said:
FWIW: There's a block diagram of the hydraulic system in the service manual that shows the connections between system components. Considering the symptoms you described (tractor working properly, then a 1 week shut-down, now 3PH doesn't lift. All other hydraulics work OK) it doesn't seem likely that the problem is with the hydraulic power source. You mentioned a Top and Tilt; is this controlled by the auxiliary control valve? According to the block diagram the hydraulic pressure first goes through the auxiliary control valve before reaching the main control valve that operates the 3PH. Is this correct? If you raise the position lever and then move the auxiliary control valve is there any movement of the 3PH?

Are you able to manually lift the lift arms?

shutt40 · Mar 18, 2009

The problem is in the valve for your top/tilt. It could be that one of the spools is not going back to the center position and fluid is bypassing. try just moving one spool at a time and see when your 3pt starts working again. Or it could be your power beyond port in that valve. Try taking the line off that runs from the top/tilt valve to the 3pt and then remove the power beyond adapter and check the o-ring. If it doesn't have a power beyond adapter it could be that the back pressure has damaged the valve.
Frank

jhwentworth · Mar 19, 2009

stumpfield said:
Yes. That's exactly the sympton. Top and Tilt is controlled by auxiliary control valve. After reading your post, I tried to raise the 3ph and move the Top/Tilt control at the same time. It works! Now I can raise and lower the 3ph with the position control lever. Not for long though. I can raise it up and down just a few times then it stops working again. If I just move either the Top or Tilt lever back and forth just slightly, then I can raise the 3ph again. If I keep moving it up and down and it will continue to work for as long as I keep raise and lower in a regular interval. If I stop and let it sit in either up or down position for a minute or so, it stops working. What do you think is wrong?

First, what brand is the TnT and how long has it been installed on your tractor? Any chance there is warranty on the valve? The web site for the manufacturer of the TnT and/or the valve might have some troubleshooting help.

Second, I'd GUESS that if you opened the valve that there would be something fairly obviously wrong, but I'd make sure of the warranty status before opening.