M6800 hydraulic & shuttle shifter issues

[DrankTheOrangeKoolaid]

Last summer I bought a M6800 w/ M920 loader at auction. When I got it home, I noticed that the hydraulics were flaky. When it warmed up, the loader didn't have the power to lift the front wheels off the ground and the power steering would stop working. I was planning to change all the fluids anyway, so I drained the hydraulic fluid and it looked like coffee creamer. I got some cheap hydraulic fluid (cheaper than UDT anyway) to flush with, then changed the filters and filled it up with fresh UDT. I then ran into a problem trying to put the loader back on (I had taken it off to make it easier to work on the tractor). The bucket wouldn't tip to push the loader into the frame. Took me a while to figure it out, but one of the couplers had lost the valve so the other valve was not opening... off to get an new coupler. Got the loader attached and everything appeared to be good. But, I am still having issues. First problem I noticed was this winter, I needed the tractor on a day that was about -30C. The tractor was stored in a Shelter Logic garage in a box, was plugged in and had a battery minder going. Started like a dream, but even after an hour of idling, it would not raise the bucket and there was no power steering. Yesterday I noticed a strange behavior when I turned off the tractor. I went to lower the bucket to rest on the ground, but it stopped a few inches before the ground... and now, the shuttle shifter is refusing to go into the forward position, I had to drive in reverse to get back to the yard.

Not sure where to start looking. Could the missing valve from the coupler be floating around somewhere causing a flow issue? I'm hoping I don't have to purchase a flow meter, do people rent those things?

Any help appreciated.

 

[Dave_eng]

Since no one else is getting into this let me ask a few questions.

From glancing at the WSM, there are separate hydraulic pumps for the power steering and the 3 pt hitch and everything else.

What i also see is that the two hydraulic pumps share the same suction line. I would focus on that line looking for any defect which would allow the pumps to be sucking air.

The issue with the loader not want to lower fully has got to be something simple. A quick coupler not fully seated. If the loader valve is cable operated, a loose cable.

Is your shuttle hydraulic or synchro?

How many lines connect to your loader valve..... 6 or 7?

Buying a 0-3,000 psi pressure gauge would be a well spent $30. Buy a quick coupler end for the gauge which you can plug into a loader line port which you first disconnect. Also into a rear remote of you have those.

You are not at the point of needing a flow meter yet.

Dave

 

[DrankTheOrangeKoolaid]

Since no one else is getting into this let me ask a few questions.

From glancing at the WSM, there are separate hydraulic pumps for the power steering and the 3 pt hitch and everything else.

What i also see is that the two hydraulic pumps share the same suction line. I would focus on that line looking for any defect which would allow the pumps to be sucking air.

I will investigate that, thanks.

The issue with the loader not want to lower fully has got to be something simple. A quick coupler not fully seated. If the loader valve is cable operated, a loose cable.

Just to be clear, the loader will lower fully if the tractor is running; it is only if the tractor is off and I'm lowering the loader with gravity that it stops short.

Is your shuttle hydraulic or synchro?

Synchro (according to WSM)

How many lines connect to your loader valve..... 6 or 7?

7 (glad I checked, I would have sworn it was 6)

Buying a 0-3,000 psi pressure gauge would be a well spent $30. Buy a quick coupler end for the gauge which you can plug into a loader line port which you first disconnect. Also into a rear remote of you have those.

You are not at the point of needing a flow meter yet.

Great idea. Off to princess auto I go.

 

[DrankTheOrangeKoolaid]

OK, got a pressure gauge and did some crawling around under the tractor. The suction line looks undamaged, so I don't think it is drawing air into the system there. The pressure at all 6 couplers (4 for FEL and two rear remote) was around 2,300-2,350 psi.

After doing more reading, I don't think the shuttle problem is related to the hydraulics... pity, I was hoping I only had one problem to deal with not two.

Any suggestions for next steps diagnosing either of these problems?

 

[Dave_eng]

With a synchro shuttle the only thing you can check before tearing into the transmission is the linkage and rod whose length you can adjust.

Your main pump hydraulic pressures look great so anything obstructing the system such as missing quick coupler parts seems unlikely.

Dave

 

[Tx Jim]

How are you determining from WSM that your tractor has sync-shuttle? I once owned a M4900 with sync-shuttle that hung in reverse & required R&R of shuttle assembly which required a tractor split at clutch housing . As it turned out the forward synchronizers were worn out. Are you 100% positive you have all FEL quick couplers seated properly????

 

[SidecarFlip]

Sounds to me like a lot of your issues stem from crud floating around in the system from the old, nasty fluid. Valves are touchy. When you drained the old crap out, did you also change out the filters? and if you did, did you cut them open and inspect them inside for junk?

 

[DrankTheOrangeKoolaid]

Sorry for the late reply, I'm splitting my time between two locations and too many projects.

With a synchro shuttle the only thing you can check before tearing into the transmission is the linkage and rod whose length you can adjust.

The linkage all move freely and the rod length is correct. I disconnected the rod and tried shifting by hand, can shift to reverse, but not forward.

How are you determining from WSM that your tractor has sync-shuttle?

Strictly from the specifications section of the manual. It is my understanding that Kubota didn't make an M6800 with hydrostatic shuttle until 2005 (based on the engine serial # and the info in the WSM, mine is a 2000).

I once owned a M4900 with sync-shuttle that hung in reverse & required R&R of shuttle assembly which required a tractor split at clutch housing . As it turned out the forward synchronizers were worn out.

I have resigned myself that splitting a tractor is probably something I will be doing in the near future. I have been reviewing this thread for inspiration.

Are you 100% positive you have all FEL quick couplers seated properly????

I have checked and double checked, I am 100% positive. One thing I did notice when checking is that most of the quick couplers are the ISO (pointy check valve) style, but one of them has been replaced with the round style... is it OK to mix and match or should I be replacing that with the correct coupler?

Sounds to me like a lot of your issues stem from crud floating around in the system from the old, nasty fluid. Valves are touchy.

That is quite possible, is there something like Sea Foam that a person can add to the hydraulic fluid to give the system a cleaning before draining and flushing? Looks like I will be draining the hydraulics again if I have to split the tractor might as well give it another flush while I'm at it.

When you drained the old crap out, did you also change out the filters?

I did change the filters.

and if you did, did you cut them open and inspect them inside for junk?

I did not, but they are still sitting with the old fluid waiting for a trip to the oil drop off. I will grab the hack saw and see what is inside. On the plus side, the magnet did not have any metal fillings stuck to it.

As for splitting the tractor, if I am understanding the WSM, I can get at the shuttle assembly via the clutch housing, so I don't need to remove the transmission from the differential. I will need to split at the engine/clutch junction. I then remove the clutch, release bearing and linkage. That gives me access to the Shuttle Case Assembly which can be removed by removing two nuts and five screws and then using two M8 bolts to pop the assembly free. Does that sound about right? Sounds easy if you say it fast enough.

 

[SidecarFlip]

You can use clean diesel fuel as a flush. Just don't leave it in there and use the tractor for work and not ever in an HST transmission.

 

[DrankTheOrangeKoolaid]

I am trying to split the tractor and I'm stumped. I have everything supported and the bolts out, but it will not come apart. With the application of leverage, I can get some separation at the top (enough to slide a putty knife into the gap), but as soon as I release the leverage the gap closes up. Honestly, it feels like I missed a bolt somewhere, but I've been over it and over it and I can't find it. The WSM isn't a lot of help for this one, all it says is

1. Hoist the engine by the hoist and chain.
2. Remove the engine mounting screws and nuts, and separate the engine from the clutch housing.

Anybody know how many bolts/nuts there should be? What I have found is:

Top: 2 nuts, there is a hole that looks like it should have a bot but does not.
Right side: 3 bolts
Left side: 2 bolts
Bottom: 2 bolts

On the left side, the equivalent location of the 3rd bolt on the right side is where the starter is located. I removed the starter in case someone thought that was a good spot for a bolt, but there wasn't one.

Any help appreciated.

 

[DrankTheOrangeKoolaid]

Got it! I went and had a look at the online parts catalogue, it has nice exploded diagram of everything. And I found two studs that go right through the fly wheel housing and into the clutch housing. I had looked at those yesterday and thought "naught to do with the clutch housing." Now I know better.

The tractor is now in two and I'm in the process of removing the shuttle shifter assembly.

 

[DrankTheOrangeKoolaid]

Shuttle assembly is out and I found these rattling around in the bottom... that can't be good.

 

[DrankTheOrangeKoolaid]

It's alive!

Took the shuttle shifter assembly to the dealership for repair. Put it back in and then wrestled the two halves of the tractor back together. Finally got the last of the hoses, cables, connecting rods and wires back where they belong. FEL sub frame back in place (those things are heavy!) Replaced fluids and fired it up. Moves forth and back.

Now to flush the bejeebers out of the hydraulics.

 

[DrankTheOrangeKoolaid]

So I started by flushing with diesel, it took about 18l to get the level above the return line. And it took 8 flushes to get mostly clear diesel draining out again. I left the FEL off for the diesel flushes, but I did remove hoses and open drain plugs to get as much of the old fluid out as possible without actually dismantling the cylinders. Then I flushed with cheap (less expensive than UDT anyway) hydraulic fluid. Then I attached the FEL and flushed again. Then I filled it up with cheap stuff. I plan to use it for light duties (pulling a post pounder shouldn't put too much load on it) for 20 or so hours, then I will drain it and fill it with UDT and install new filters. Based on the amount of flushing I have had to do, I'm thinking that when I had it split I should have removed the transmission and pressure washed inside the rear diff and the transmission and used a shop vac to clean out the old crud. Based on the stated capacity and the amount of fluid it takes to fill it up, there is 4-5l of old stuff left after it is drained.

I'm pretty sure I found where the water was getting in. The boot on the main shift lever had a big tear in it. The tear was in a spot where you didn't see it unless you went looking for it. Because of the shape of the boot, it acted like a funnel and collected rain and directed right into the transmission. Based on the amount of dirt and crud inside the boot and around the lever, that tear must have been there for years. So I'm hoping that SidecarFlip is correct and my hydraulic issues are due to the old crud that was still floating around in the system.

 

[SidecarFlip]

My open station M9 also has a torn mainshift boot that I replaced when I first serviced it and the old fluid was the color of a coffee with lots of creamer. The way the shift lever is, if the tractor is outside in the weather, water goes right in the shift tower and right in the transmission case.

 

[DrankTheOrangeKoolaid]

I left the diesel that I flushed with to sit for a few days, then I siphoned the clear diesel off. This crud is what I was left with!



I'm not sure what it is, but it goes through a 10micron filter like it wasn't there. I will have to see what comes out when I change out the cheap hydraulic fluid. I might not be done flushing yet.

 

[SidecarFlip]

Looks like radiator stop leak to me. It also looks like what you put in a PEX floor heat closed system to seal up any joint leaks.

 

[DrankTheOrangeKoolaid]

Update: we finally got some -30C weather (never thought I would be happy to have a week of -30 temperatures in the forecast ) so I could test the hydraulics in the cold.

I plugged the tractor in last night and put the battery tender on it. This morning it was -34C at 7:30. I went out and started the tractor. It was not overly enthusiastic about this, but fired up on the second try. I left it idling at 1,200 to 1,300 rpm and went back inside to finish my coffee. An hour later the temperature gauge had hardly moved. I gave a small pull on the FEL joystick, heard some creaking and groaning but the bucket didn't seem to move. Before I could start cursing under my breath, I heard a loud pop and the bucket lifted off the ground... it had been frozen to the ground. The FEL was able to lift the front end off the ground (the front tires were also frozen to the ground) and I had steering. So I am cautiously optimistic that the flushing of the hydraulic system has solved that problem.

For those of you in cold climates, how long and at what rpm should I have to idle the engine to get it up to operating temperature?