John Deere 300 b backhoe select hydraulic problem

[oldnslo]

Does the hoe seem to have digging force? If yes this would indicate the pump is operating and that there is problem with flow to the loader circuit. With out a good schematic I wouldn稚 even hazard a guess as to what the problem could be.

 

[mdean]

Suzukibruce, any update on a solution? I have the same exact problem! I removed the fuel tank for repairs (had to remove Hydraulic reservoir) and now having problems with hydraulics. It seems in my case the reservoir is not getting supply from Main transmission pump now, which is odd since everything was working prior to removing the fuel tank for repairs.

 

[Garrie Nolting]

When its working, both the hoe and the loader have working force. When its acting up neither, have force and move very slow. It's like the main pump is starved for oil. There is also a notable difference in the steering force when its acting up. Thats why I thought the problem was with the "pressure control valve". As i understand it the valve provides oil to the steering first, always, then to the main pump.

 

[Garrie Nolting]

I havent done anything more on it. Still trying to get ideas of what to try. Wish I could find someone who knows what size of an orifice should be in the Pressure Control Valve.

 

[Tx Jim]

I havent done anything more on it. Still trying to get ideas of what to try. Wish I could find someone who knows what size of an orifice should be in the Pressure Control Valve.

If you think orifice is your tractors hyd problem which I doubt it is, just install a new orifice from JD. R40562 ORIFICE,PRESSURE CONTROL ADD 11.58 USD

 

[Tx Jim]

. As i understand it the valve provides oil to the steering first, always, then to the main pump.

Not exactly. Trans pump must supply oil to frt hyd pump which then frt pump should make 2250 psi then pressure is sent to power steering then on to pressure control valve. If pressure is 1700 or below it won't get past pressure control valve. Have you tried manually filling frt hyd oil reservoir?

 

[buickanddeere]

Suzukibruce, any update on a solution? I have the same exact problem! I removed the fuel tank for repairs (had to remove Hydraulic reservoir) and now having problems with hydraulics. It seems in my case the reservoir is not getting supply from Main transmission pump now, which is odd since everything was working prior to removing the fuel tank for repairs.

Were the lines swapped ?

 

[buickanddeere]

When its working, both the hoe and the loader have working force. When its acting up neither, have force and move very slow. It's like the main pump is starved for oil. There is also a notable difference in the steering force when its acting up. Thats why I thought the problem was with the "pressure control valve". As i understand it the valve provides oil to the steering first, always, then to the main pump.

From the front pump to the priority valve and then to the rest of the high pressure hydraulics if the psi is 1700+. Transmission pump forces any oil left over after lubing the transmission , the pro brake , the pro clutch and high low if so equipped . Oil not used by the front pump fills the reservoir and oil cooler. Then the oil flows back to the transmission case , partly by gravity .
Is there a high pressure valve somewhere that is passing oil when no hydraulic functions are being called for ? There is much confusion between open and closed Center hydraulics .

 

[Suzukibruce]

Sorry about lack of communication. So I found the main pump failed so I rebuilt that and both loader and back hoe are working. I redid the cylinders for the backhoe and all pins and bushings.

 

[Suzukibruce]

Sorry about lack of communication. So I found the main pump failed so I rebuilt that and both loader and back hoe are working. I redid the cylinders for the backhoe and all pins and bushings.

Now I知 not getting the hydraulic fluid circulating into the reserve tank. The return hose is ok. I need to check the valve today. Any other suggestions?