3-Point Hitch L5740 Engine Hunting @ Idle

[KOLBRNR]

Hi folks. I'm looking for some possible solutions to a new problem on a new to me tractor.

I recently bought a 2011 kubota L5740 HSTC. The other day I had a woods 5' bush cutter on the tractor and was running down the road from my field to my home as I wanted to wash the bush cutter off after using it. When I backed in the driveway and the tractor came to an idle I noticed the engine hunting between 800 and 500 RPM. When I lowered the bush cutter the engine seamed to smooth out. I now have a new noise that sounds something like a pressure relief valve bypassing but it isn't. The sound is coming from the pipe that is tied into the 3 point hitch hydraulic circuit, If you hold the pipe you can feel it resonate. This sound is only when the engine is at a certain rpm. It goes away above or below.

There was at one point coming down it sounded like the engine came under a load and then it went away,

I took it to the dealer and they disassembled the pipe to see if something was in there and it's clean. They have adjusted the feedback rod for the three point hitch just to see if it was that going over the relief valve. I left it there for them to try and figure it out.

Any ideas?

 

[wmonroe]

Do you have any rear remotes that could be jammed or blocked in the "on" position?

 

[ritschner]

This:

"They have adjusted the feedback rod for the three point hitch just to see if it was that going over the relief valve."

To check if this is the issue, just lower the three point slightly. If it quits hunting and smooths out, then problem solved. Mine will do the same thing if the three point lever is hard against the stop. The plastic that surrounds the lever on mine is starting to wear so it is about due for a feedback adjustment. The new noise may just be a harmonic that you may not have heard before. Usually after an issue appears, you will start to hear all kinds of noise you never heard before. Does it occur both with and without implements attached, just certain ones, or all the time. It may be caused by the weight of the implement setting up a vibration?

 

[KOLBRNR]

Do you have any rear remotes that could be jammed or blocked in the "on" position?

The remotes are in the center position. I tried them back and forth to check that.

 

[KOLBRNR]

This:

"They have adjusted the feedback rod for the three point hitch just to see if it was that going over the relief valve."

To check if this is the issue, just lower the three point slightly. If it quits hunting and smooths out, then problem solved. Mine will do the same thing if the three point lever is hard against the stop. The plastic that surrounds the lever on mine is starting to wear so it is about due for a feedback adjustment.

Mine still does this even if the three point hitch is partly lowered.

 

[Leejohn]

A bush hog is heavy. On your way home was you running in high? Was the mower bouncing much, if so you might have them to check the safety valve.

 

[KOLBRNR]

A bush hog is heavy. On your way home was you running in high? Was the mower bouncing much, if so you might have them to check the safety valve.

How do they check the safety valve? There are a few bumps but I slow down. However the bush cutter did rattle on one of the bumps.

 

[Leejohn]

The dealer should know how and it should be one of things to check, it's for the 3pt. I'm sure they well have service manual.

 

[KOLBRNR]

I asked about that very thing this morning. They said they didn't really have a way of checking it. Makes me wonder. I know the service manager real well. Since grade school, like 40 years. He's been around tractors and equipment his whole life. Worked for several companies as a mechanic, grew up on farm the wholed nine yards. I left it with them to figure out. My bush cutter bounced once a bit but it only weighs 800 pounds. What will happen this winter when I hit a pot hole with an 1150 pound snow blower on the back?
Anyway, I bought the tractor from them 6 weeks ago. It's not like they're free and clear. I'll keep you guys posted. Thanks for the ideas, please keep them coming.

 

[KOLBRNR]

Okay. Tractor is back from the dealer and here's the story.

The hunting was due to the control rod needing adjustment. They lengthen the rod until the fluid goes over the relief valve and then shorten it by 2 complete turns.

The noise was a pin down beside the control valve that was vibrating and caused the pipe to act as a speaker amplifying the noise.

They hung a weight on the three point hitch for hour and it dropped 3/16" with the engine off. They say the hunting is gone and I know the noise is gone. I left without a bill and was told to try it out. Next time I have the bush cutter on I'll see how it goes.