M7040 shuttle problem

[Mark Robke]

I have a m7040 that has hydraulic shuttle shift. When it is cold, it works fine but when it gets warm, after @ 1 1/2 hrs of run time, it will either hesitate, or, not shift into forward. Reverse will work but will usually jerk. If I lower the rpms it will work better, but it will jerk really hard when it engages. It does not matter if I shift reverse to forward or just step on the clutch when going forward and then continue forward motion. You can't feather the clutch- it will just jerk forward, or, not move at all. Lowering rpm to idle helps, but this is not feasible most of the time. I read the workshop manual and how to test the pressures at the shuttle valve on the side of the transmission, but the manual does not say what to do if the pressures are incorrect. Also you have to remove the left rear wheel/tire, the fender and fuel tank to access the valve. So by that time you could not duplicate the problem, because it would have cooled down. I suspect the shuttle valve to be the problem, but it costs $1900+ so I want to be correct before I replace it. I have changed the fluid and filters ($550) and that only helped a tiny bit, if at all. I don't think the filters had many hrs on them though, and the fluid really was clean, as were the filters. Since the problem occurs whether you use the clutch or the lever, and that it is hard to modulate/feather the clutch, and that only happens when warm makes me think this is a sticking modulator valve in the shuttle valve body. Again it shuttle shifts fine when cold, and it takes usually over an hour and a half of run time to act up. It does NOT slip once engaged in gear. The valve on the tractor looks unpainted, as though it was changed before.
Another thing I recently discovered, the serial # says it is an M7040DT which means it should be mechanical shuttle, but the hydraulic shuttle is M7040HD.
Anyway, does ANYONE have an idea, experience with this problem? Any way to prove what is the cause? Thanks, Mark.

 

[North Idaho Wolfman]

What were the pressures?

 

[Mark Robke]

What were the pressures?

I have not checked them as of yet. Need to remove wheel, fender and fuel tank. The tractor would not be warmed up enough to duplicate the problem. So at cooler temps I would suspect good readings because there is no problem when cool. Thanks, Mark.

 

[whitetiger]

I have not checked them as of yet. Need to remove wheel, fender and fuel tank. The tractor would not be warmed up enough to duplicate the problem. So at cooler temps I would suspect good readings because there is no problem when cool. Thanks, Mark.

Remove the wheel, and remove the fuel tank. Install a gauge or gauges. Fix a 2.5-gallon jug in place under the operator's platform, fill it with fuel, and insert the suction and return fuel hoses in the jug. Tape the hoses in place. You can now run the tractor and read the pressures.

 

[JasonW]

I will add you can remove the fuel tank without removing the tire. Even though the instructions state to remote the tire to drop the fuel tank.

I installed a creeper gear set on my M6040 right after I bought it, I did have to remove the fender though. Full access to the shuttle valve.

 

[Mark Robke]

Remove the wheel, and remove the fuel tank. Install a gauge or gauges. Fix a 2.5-gallon jug in place under the operator's platform, fill it with fuel, and insert the suction and return fuel hoses in the jug. Tape the hoses in place. You can now run the tractor and read the pressures.

If the pressures are wrong, what is the next step? The manual does not say. Can there be a problem elsewhere, or is the valve the problem?
I have previously considered doing what you said, But my holdup is I need the tractor for haying right now, and that rear wheel is loaded, weighted, and has a cast center. I'll need another tractor to lift it and move it. And I'm not young anymore!
I also was really hoping someone else would have had this problem so I would have some insight. I have asked around - 2 dealers, another forum and a few tractor mechanics -no one else has heard of this happening.
So anyway, if the pressures are right, or, wrong, what is the next step? Thanks, Mark.

 

[Fedup]

My take is simply this. There are obviously hundreds of these tractors out there using this system. Since it's not electronic (like so many others) I suspect it's likely more dependable and fewer problems come up so actual experience is limited. Therefor fewer problems get reported and discussed. I know of some tractors in the area with similar systems. None have had any problems that I've heard of so I have nothing specific to offer. I will however, follow this discussion and when you find time to delve into it, should you decide to do so rather than farm it out, maybe I'll have something to add.

 

[Russell King]

The answer to the question about the next steps will be to then adjust the pressure if it is lower or higher than specified by adjusting a relief valve or two in the system, replace pump if pressure is really low, or replace tubes or hoses if they are damaged. It may be a control valve that is damaged or malfunctioning that needs to be repaired.

The workshop manual should have a description on what to check and then suggested steps to take afterwards. Is there not a troubleshooting section for the transmission?

 

[JasonW]

Maybe you missed it. You do not need to remove the tire to drop the fuel tank.

 

[Mark Robke]

The answer to the question about the next steps will be to then adjust the pressure if it is lower or higher than specified by adjusting a relief valve or two in the system, replace pump if pressure is really low, or replace tubes or hoses if they are damaged. It may be a control valve that is damaged or malfunctioning that needs to be repaired.

The workshop manual should have a description on what to check and then suggested steps to take afterwards. Is there not a troubleshooting section for the transmission?

First of all, the manual does not say what to do if shuttle valve pressures are wrong. I agree that it should. I was at a Kubota dealer and we both read it again on his computer (I have it downloaded at home) and he was surprised too. The only trouble shooting for the transmission concerns the transmission gears- nothing about the shuttle not working. I should have added I checked the hydraulic pressure at the remotes when the problem occurred, and it was about 2700psi, which meets specs.
I have studied the hydraulic flow charts for the shuttle valve in the manual as best I can, and my suspicion is that the modulator valve sticks for some reason. As best I can tell the modulator valve is common to both the clutch pedal and the shuttle shift lever. It never matters whether you depress the clutch or change directions with the shift lever, when the problem is occurring, the tractor won't move until I lower rpms. It has never happened when it was cold. It only happens after running at high rpm for over an hour working. The shuttle valve does appear to be able to be disassembled. Thanks, Mark.

 

[Mark Robke]

My take is simply this. There are obviously hundreds of these tractors out there using this system. Since it's not electronic (like so many others) I suspect it's likely more dependable and fewer problems come up so actual experience is limited. Therefor fewer problems get reported and discussed. I know of some tractors in the area with similar systems. None have had any problems that I've heard of so I have nothing specific to offer. I will however, follow this discussion and when you find time to delve into it, should you decide to do so rather than farm it out, maybe I'll have something to add.

I agree that this system must be dependable according to all I read before I bought the tractor. I was just hoping to find that someone else had this happen too, and what the solution was. As you say it must be an uncommon problem, which is good. Thanks, Mark.

 

[Mark Robke]

Maybe you missed it. You do not need to remove the tire to drop the fuel tank.

No I didn't miss it, and looked at it, thinking maybe it is possible, but I was going by what the book said. Also the tank would have to drop straight down, as the wheels are in close. Thanks, Mark.

 

[North Idaho Wolfman]

Part of what you are describing sounds like bad seals on the clutch pack itself.
If the clutch pack has bad seals it will not pressurize correctly and give the proper feed back to the modulator valve.

The WSM can "hide" information in them.
Are you looking in the hydraulic section of the manual?

 

[Mark Robke]

Part of what you are describing sounds like bad seals on the clutch pack itself.
If the clutch pack has bad seals it will not pressurize correctly and give the proper feed back to the modulator valve.

The WSM can "hide" information in them.
Are you looking in the hydraulic section of the manual?

Part of what you are describing sounds like bad seals on the clutch pack itself.
If the clutch pack has bad seals it will not pressurize correctly and give the proper feed back to the modulator valve.

The WSM can "hide" information in them.
Are you looking in the hydraulic section of the manual?

Would the clutch pack seals allow slippage? It does not ever slip when the problem occurs, and when it engages, it does not slip. One time in the winter when it was pretty cold, I had it act like it was lunging between neutral and forward, but that quit as it warmed up. I will 'search 'the WSM right now in the hydraulic section. Thanks, Mark.

 

[Mark Robke]

Would the clutch pack seals allow slippage? It does not ever slip when the problem occurs, and when it engages, it does not slip. One time in the winter when it was pretty cold, I had it act like it was lunging between neutral and forward, but that quit as it warmed up. I will 'search 'the WSM right now in the hydraulic section. Thanks, Mark.

I did some searching and re-reading, and actually I have read this before. The hydraulic section is only about the pump and the 3pt lift, does not even say anything about the remotes. And nothing about shuttle problems. Even the transmission section shows the shuttle's hydraulic flow in every scenario except letting the clutch out. Shows it released and depressed, the lever forward, neutral, and reverse. If this info is there, I cannot find it. And it tells what the shuttle valve pressures should be but nothing about if they are wrong. Thanks, Mark.

 

[North Idaho Wolfman]

All the information you need is on pages 3-M7 thru 3-M12 and 3-S13

It shows all the test ports and all the pressures to expect at each port under different conditions.

You mentioned checking the pressure at the remotes, that really doesn't tell you anything about the pressures of the shuttle valve.

 

[Mark Robke]

All the information you need is on pages 3-M7 thru 3-M12 and 3-S13

It shows all the test ports and all the pressures to expect at each port under different conditions.

You mentioned checking the pressure at the remotes, that really doesn't tell you anything about the pressures of the shuttle valve.

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I was pointing out to someone that replied that the pump was ok. I have read this info about the shuttle pressures, but it does not say what the next step is if they are wrong. Which, I guess, has been my main question all along. I even read this info with the local dealer, and he agreed that there was no info what to do if they are wrong. I do have the same manual, and I do appreciate your efforts. Thanks, Mark.

 

[North Idaho Wolfman]

The pages 3-M7 to 3-M12 have the instructions on the bottom of every page on what part needs to be serviced if the pressures are wrong.

 

[Mark Robke]

The pages 3-M7 to 3-M12 have the instructions on the bottom of every page on what part needs to be serviced if the pressures are wrong.

With all due respect, I don't see any instructions at the bottom of any of those pages. I just read what is going on in a correctly operating valve. Thanks, Mark.

 

[North Idaho Wolfman]

With all due respect, I don't see any instructions at the bottom of any of those pages. I just read what is going on in a correctly operating valve. Thanks, Mark.

Exactly, you read what is going on with a correctly operating valve, so any deviation will point to the problem, be it the proportionally reducing valve, the shuttle valve, the inching valve and so on.
It's a testable process of elimination.
Do all the pressure tests in all possible test scenarios and it will point to the problem or problems if there are multiple issue.
Testing these kinds of issues is a simple matter of you will see this pressure or the lack of pressure (bad behavior) and it will be caused by this fault (bad part).