M7040 hydraulic shuttle problems,

[Confused8122]

I have a m7040hdc with hydraulic shuttle. 3000hrs. I bought used a few years ago with 2600hrs. When I got it, it was winter and cold. There was a large delay going into gear until the oil warmed up. I changed the oil and filters, useing sudt2 and Kubota filters. The delay got better, but didn't go away, reading it sounded normal. It was ok and manageable.

Fast forward to now, I use the tractor way more often, for way more things. Started making our own hay, etc.

this summer I noticed that even in the warmer temps, there is a delay going into gear. It seems to get worse when fluid is hot, but not always. It never slips, always does work. Engagement is harsher than I think it should be. Clutch pedal is difficult to use, with trans In gear, tractor stopped , let clutch out until it just grabs, and because of the delay, it is to late and engages completely, harshly.

I have changed fluid and filters again. Tried to check as much as I could, without any changes. Reading the wsm, I suspect the shuttle valve, the modulation valve or accumulate valve, but I don't know hydraulics that well . I did get some pressure gauges and checked pressures, the gauge confirms the delay, but I don't know what it means. Any help? Do I need a new shuttle valve? New clutch pack?

I took some video, I will try to post or link to. 1 is m port, 1 is r port
Pressure videos

2 new videos · Sunday, Sep 7 🎬

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Thanks
Nick

 

[Tx Jim]

I tend to think the clutch control, shuttle control or modulation valve is at fault. I'll be monitoring your thread due to my owning a '11 M7040 HDC tractor with 2000 hrs on speed/hr meter that so far has performed very well.

 

[Confused8122]

Yes, those 3 valves are all built into 1 assembly. Hoping someone with knowledge and experience can confirm.

I forgot to say that everything else works good. Steering and pto work well and engages. Loader and 3 point ok. Remotes ok.
I have tried searching the site, and can find potential similar problems, but either they don't test pressures, or don't come back with a solution.

Nick

 

[Confused8122]

So not sure what to do, but in my gut the problem is the shuttle valve. It's a expensive valve. Alot to spend and not be sure that is the problem. I thought I would ignore it for a bit, but then decided that I do alot of detail work and I need the tractor to be predictable, safe to creep up to an object.
I found a used valve with some Google searches and ordered. I installed it yesterday and the tractor seems to be fixed. It shifts into motion with a normal delay and engagement, not a long delay and harsh. The clutch pedal is responsive and very predictable.
I measured pressure again, but honestly they weren't much different. The biggest thing was the delay. If I let the clutch out quickly to a point, and then hold it, the pressure would continue climbing. It doesn't do that now.
I can operate the tractor without getting whip lash or worry about crashing into something.

 

[Confused8122]

I disassembled the shuttle valve, and I did find a broken spring. My best guess looking at wsm and hydraulic diagrams, is it was the modulation valve part.

 

[Tx Jim]

Congratulations on your successful repair. Could you please post a photo of your tractors shuttle valve & broken spring?

 

[Confused8122]

Some pictures.
The spring is missing about a coil and a half. I had the piece but lost it on my bench somewhere. I suspect it was either jammed or no longer putting the proper pressure on the left most piece, which is a type of spool.

The picture installed is as I was in process of removing. The white goop is excessive thread sealant on test port.

 

[Confused8122]

Congratulations on your successful repair. Could you please post a photo of your tractors shuttle valve & broken spring?

Does that work? Or are you looking for a different picture? I'm happy to try and take one that helps someone else later.

 

[Tx Jim]

Thank you for posting your photos more especially of the broken spring.