2019 L47 TLB HELP!

[Imoveorangedirt]

Hello orange tractor enthusiast,

long time supporter first time poster.

Hoping there may be some hydraulic/mechanic wizardry one can impart on me. I have a 2019 L47 TLB that I’m experiencing issues with on the backhoe. Because it is under warranty the dealer just underwent diagnostic testing, which led to a new part and unfortunately it marginally improved the problem. I think it’s pertinent to add that kubota and the dealer both agreed there was a problem tho diagnostics did not yield proof of failure.... a new backhoe control valve was ordered and installed.
So this is what it’s doing...any time you run the backhoe and try to pull in the boom and operate any other function simultaneously, the boom stops. If you lightly feather all the controls the boom can be operated with a another backhoe function without it stopping. This “work around” is painfully slow. If you try to run the controls at any normal speed the boom always stops when you add another function ie. dipper in or out, bucket curl, boom swing etc. Also, it only does it when you’re pulling in the boom. Any thoughts???

 

[Captain13]

The dealer should look at the pressure relief valves. If one is faulty it is going to drop the system pressure because it is sending the fluid back to the tank instead of to the pressure port. I think the backhoe is ported off the FEL and the dealer probably replaced the FEL control thinking it’s bypassing fluid. If it is the relief valve, the fluid will be sent back to the tank instead of the pressure port supplying the backhoe.

 

[Imoveorangedirt]

The dealer should look at the pressure relief valves. If one is faulty it is going to drop the system pressure because it is sending the fluid back to the tank instead of to the pressure port. I think the backhoe is ported off the FEL and the dealer probably replaced the FEL control thinking it’s bypassing fluid. If it is the relief valve, the fluid will be sent back to the tank instead of the pressure port supplying the backhoe.

captian13,

thanks for the reply. The dealer replaced the backhoe control valve. To the tune of 5.5k I’m told(under warranty). I’m wondering if it could be a problem with the cylinder, thoughts?

 

[Captain13]

I may be wrong on how the L is supplying hydraulic fluid to the backhoe, but if it’s a power beyond port coming off the FEL, the problem may be with the pressure relief valve there and not the backhoe control. if a cylinder is bypassing fluid, it usually just doesn’t have the pressure to function properly. I assume they checked the pump output pressure. It sounds like there is not adequate pressure. That’s why I thought a relief valve may be faulty or stuck partially open.

 

[Imoveorangedirt]

I may be wrong on how the L is supplying hydraulic fluid to the backhoe, but if it’s a power beyond port coming off the FEL, the problem may be with the pressure relief valve there and not the backhoe control. if a cylinder is bypassing fluid, it usually just doesn’t have the pressure to function properly. I assume they checked the pump output pressure. It sounds like there is not adequate pressure. That’s why I thought a relief valve may be faulty or stuck partially open.

yes everything was tested and is within spec.

 

[Captain13]

Does the backhoe use quick disconnects on the hoses? If so, make sure the pressure is relieved, then disconnect and reconnect the hoses.

Also, check to make sure all of the valves that you are not using are in the neutral position. In other words, check all the valves including the rear remotes if you have them to make sure one is not hung in a partially open position. If it’s not a relief valve, then fluid is bypassing a spool valve or a quick disconnect is not properly seated.

 

[Imoveorangedirt]

Does the backhoe use quick disconnects on the hoses? If so, make sure the pressure is relieved, then disconnect and reconnect the hoses.

Also, check to make sure all of the valves that you are not using are in the neutral position. In other words, check all the valves including the rear remotes if you have them to make sure one is not hung in a partially open position. If it’s not a relief valve, then fluid is bypassing a spool valve or a quick disconnect is not properly seated.

Captain,

thanks for this. I’ve checked all of the above and all normal. It does look like the backhoe control valve is ported off of the FEL. I’m digging thru the shop manual trying to understand the routing and workings of the valves etc and have to admit it’s a little over my head. Is the relief valve something that can be adjusted?

 

[Captain13]

it can be adjusted but it shouldn’t be adjusted. It should be replaced. They are set at the factory and should be replaced if malfunctioning.

The FEL relief valve is probably handling the backhoe as well. Idaho Wolfman may see this and give you some good advice as to what to do from here.