L39 Massive Hydraulic Leak

[MikeinDewey]

I lost the front drive on my 4X4 L39TL and through this forum found that replacing one or both of the forward shaft couplings would likely be an easy fix. The parts came in and so today I got underneath and started to remove the spring pins. With the front pin removed, a final hammer whack on the pin driver addressing the rear pin resulted in a heavy rainfall of hydraulic fluid coming out from the rear shaft housing and the clutch housing drain (split pin plug). I'm sure I did something wrong and it'll be expensive to resolve, but I don't know what. Does anyone have an idea what now needs to be fixed and how best to do it? Is this something a low-level, backyard mechanic can deal with or is it heading to the Kubota service center.

 

[lugbolt]

Probably pulled the propeller shaft out of the seal. Unfortunately the design of it isn't conducive to an easy fix.

 

[whitetiger]

Looks like you are heading to the Repair Shop as you have damaged the propeller shaft seal on the front of the transmission housing. The tractor has to be separated between the engine and transmission to access the seal, sleeves, and bearing.

How did you determine the splined couplers failed?

 

[MikeinDewey]

It turns out that the splined couplers did not fail. When the front drive stopped working, I previously read about lifting the front end and exercising the wheels in various manners with the results leading to the likelihood that the fault was with the couplers. Plus, them being stripped seemed to be a not-to-rare problem. Added to that, when I looked under the tractor, I found that the bolts holding the shaft covers together had disappeared and they had collapsed and were just banging around. The clues seemed to point to a stripped coupler. Now the clues seem to point to a reduction in my bank balance.

The bigger bummer - 3 years ago the case was split to replace the propeller shaft seal.

 

[rbargeron]

..... when I looked under the tractor, I found that the bolts holding the shaft covers together had disappeared and they had collapsed and were just banging around. The clues seemed to point to a stripped coupler. Now the clues seem to point to a reduction in my bank balance. - 3 years ago the case was split to replace the propeller shaft seal.

Looks to me like the seal at the front of the trans has failed or wasn't put in right. It should prevent a fluid spill when servicing the propeller shaft. If that seal is not sealing, the fluid can leak out of the trans at that location, if the flow path forward is opened for service.

Looking at the parts drawing below, there's a spacer tube going through the clutch housing with o-rings on both ends that will "contain" the trans fluid when its all assembled, keeping the trans fluid from wetting the clutch. I think that "stack" of parts is kept snug in place by packing grease in the cover around the propeller shaft. On my L48 the driveshaft tube is full of grease too, so a small amount of trans oil getting all the way to there can't really mix much with front diff. - or tend to leak out, provided the covers are in place and the seal at the front of the trans is working .

My theory here is that with the shaft covers off, moving the rear coupling allowed the plug of grease to move, allowing the oil to flow out through the failed seal.

Now that the shaft couplings are found to be ok, I'd try sliding the rear one back and put the pin back in. Reassemble the driveshaft cover and pump grease into it to fill the clearance. Then put a few quarts of fluid in the trans and check for leaks. If a grease charge contained it before the coupling moved forward, it should work again.

Trying this will cost a ton less than breaking it all down to replace that seal. Packing the driveshaft tube full of grease should contain the oil in the trans - which isn't under pressure.

Unfortunately this doesn't address why the front axle isn't driving. For that I'd start with the 4wd shift linkage under the platform. Good luck, Dick B

 

[whitetiger]

Looking at the parts drawing below, there's a spacer tube going through the clutch housing with o-rings on both ends that will "contain" the trans fluid when its all assembled, keeping the trans fluid from wetting the clutch. I think that "stack" of parts is kept snug in place by packing grease in the cover around the propeller shaft. On my L48 the driveshaft tube is full of grease too, so a small amount of trans oil getting all the way to there can't really mix much with front diff. - or tend to leak out, provided the covers are in place and the seal at the front of the trans is working .

The seal has a short sleeve that sets on the propeller shaft and serves as its inner sealing surface. The tube and o-rings are to ensure the sleeve can not migrate forward out of the seal itself. There should be no grease involved with this setup.
There should be some grease in the splined couplers only.
The input shaft into the front axle has a seal so no oil could mix from the transaxle to the front axle.

 

[rbargeron]

See next post

 

[rbargeron]

I agree that's the way it all looks in published service information. But for some time the machines with front propeller shaft driven by a 30" long shaft coming from the rear axle through inside the clutch housing, the oil seal at the bottom has been an issue. When I took my L48 apart to replace that seal with the updated version I was surprised to see the enclosing tubes continuing to the front differential packed with grease.

I replaced the seals (and sleeves) as preventive maintenance during a split for HST repairs. In reading MikeinDewey's posts, it resonated with what I'd seen that my tractor already had - the presence of viscous grease encasing the shaft. It was clear it had been added intentionally - perhaps to inhibit oil leakage there without the large job of breaking down a TLB to replace a small seal. I put it back together as-found, with a couple of top-up grease gun strokes.

Whose idea the grease was is a mystery, but I think its a brilliant alternative to dismantling a TLB tractor. I don't think stirring the grease uses much extra fuel

Now it would be good to figure out why his front axle isn't engaging. Take care, Dick B.

 

[whitetiger]

I agree that's the way it all looks in published service information. But for some time the machines with front propeller shaft driven by a 30" long shaft coming from the rear axle through inside the clutch housing, the oil seal at the bottom has been an issue. When I took my L48 apart to replace that seal with the updated version I was surprised to see the enclosing tubes continuing to the front differential packed with grease.

I replaced the seal (and its sleeve) as preventive maintenance during a split for HST repairs. In reading MikeinDewey's posts, it resonated with what I'd seen that my tractor already had - the presence of viscous grease encasing the shaft. It was clear it had been added intentionally - perhaps to inhibit oil leakage there without the large job of breaking down a TLB to replace a small seal. I put it back together as-found, with a couple of top-up grease gun strokes.

Whose idea the grease was is a mystery, but I think its a brilliant alternative to dismantling a TLB tractor. I don't think stirring the grease uses much extra fuel

Now it would be good to figure out why his front axle isn't engaging. Take care, Dick B.

The Id of the seal is larger than the Od of the tube and o-rings so there is no way grease in the tube will stop oil from leaking at the seal.

 

[rbargeron]

The bore in the midcase that houses the seal(s) is pretty tight. If the tube spacer is big enough to prevent the sleeve from migrating forward it would be big enough to allow pumped grease to flow to that area, filling the gaps, maybe pushing past the spacer and bearing, and obstructing or stopping gravity oil flow out of the trans.

I can't be sure how things actually fit - because the tube and o-rings were added AFTER my L48 WSM was printed. The L48 drawing below doesn't show the tube - but its in the parts list. Its part number is different on the L39. There may be other differences.

I'm just noting the OP's rig didn't leak before the shaft coupling got moved - and maybe it would go back where it was. The grease idea would be additional insurance - part of reinstating the shaft covers.

Maybe MikeinDewey can let us know how his is built.

 

[whitetiger]

Here are a couple of pictures and sketches of the tube and o-rings. They clearly show the only purpose of the tube is to hold the sealing sleeve in place and the o-rings are to clamp the tube to the prop shaft so they spin together. You clearly would have to pump at least 4" to 5" of grease in the clutch housing to cover the seal, and it would just run out into the prop shaft shield as the tractor is driven.

The sealing sleeve the tube holds in place has a rubber liner in it to seal it to the shaft while the lip seal in the front of the transmission housing contacts the outside of it. In early units, the sleeve would migrate forward on the prop shaft enough that the seal had no surface to contact which naturally resulted in an oil leak. The rubber in the sleeve was changed and a tube with an o-ring was added to eliminate that problem.

 

[MikeinDewey]

That there are so many engaged and knowledgeable folks on this site is impressive!

Once I removed the spline couplings and shaft, I noticed that the shaft within the clutch housing, which connected to the rear spline coupling, was seemingly too loose - it rattled easily. Curiosity led me to lightly pull on it and it easily came out until it contacted the start of the bevel gear. On the shaft, about a foot from the end, was solid cylinder about 1/2 an inch thick with an O-ring against the face of the shaft. With my curiosity satisfied, I wiggled that shaft back in until it seated at the other end. I then reinstalled the replacement spline couplings (might just as well use the new ones), forward shaft, spring pins, and shaft covers. There was grease within the shaft covers when I removed them so I added more grease before reinstalling them. I was working on my workshop's driveway and needed to get the tractor off of that, so I filtered the hydraulic filter I recovered (about 4 gallons) and put it back in. When I dropped the tractor down (I'd lifted it using the front bucket and stabilizers and, yes, I did have jack stands all around), I was a bit surprised that the hydraulic fluid didn't immediately start leaking out, and when I parked it in its home, after a few hours, only a couple of drops of fluid had come out the clutch housing drain.

The front axel still didn't engage, so my initial problem is still there. I've accepted that it's going to need to be split again and tomorrow I'll arrange for that. When the good folks at Binghams pull it apart and figure out how to fix it, I'll pass on the results.

 

[rbargeron]

Hey Mike - good news - Hope they find something easy to fix.

Whitetiger - I appreciate your effort to illustrate this subject. I've also found more pertinent facts today.

Another place the leak can originate is not the seal itself, but between the polished sleeve's ID and the shaft. In repair videos I found from 2018, an old seal sleeve was found to be a loose slip fit on the shaft - so an oil leak was possible under the sleeve and maybe not coming thru the seal at all. The vid shows a new revised sleeve's hard rubber liner ID measures .015" smaller than an original. The new one is quite tight on the shaft (moving it takes around 75 lb). I had mentioned in my HST repair thread - post #50 that the new one's ID measured .010 smaller, and I made a driver to push it into place. My L48 had not leaked so I didn't really think about it further till this case.

The pertinent video evidence of the above is contained inside a 5-part tractor-split-and-repair video from 2018. The loose sleeve is in the last 2 minutes of Part 4 and the measurement is in the first 2 minutes of Part 5. (videos posted on YouTube by Denny's Country Life)

Knowing there could be .015" of clearance, a shot of grease could be pushed through there and help plug the trans fluid leak path. Since Mike's machine has grease in the covers too, maybe its a procedure used by some shops but not all? Take care, Dick B

 

[MikeinDewey]

Rbargeron - an incredible thread and great videos you have there. I'm not anywhere near the skill level of you and the other Wisemen and need pictures, diagrams, and Google to decipher much of what you so easily discuss. I'm in awe.

But while going through it all, it just dawned on me that when I pulled out the clutch housing's drive shaft, there was no collar (shaft guard) and only that single O-ring. That seems either mysterious or an obvious lack of me knowing what I'm talking about. I'm not sure what the purpose is of that collar but the O-rings ought to be sealing something and possibly keeping the shaft lubricated and out of water (just a guess based on the nearby clutch housing drain). What are the chances that when the unit was split 3 years ago that a reassembly step was missed?

 

[rbargeron]

There's no way to know exactly what was done last time around - take it to somebody with up-to-date manuals and parts drawings for your model and serial number. Best luck - Dick B.

 

[rbargeron]

One more idea - the loss of 4wd is likely being caused by something either in the front axle - or in the rear differential housing where the power for the front axle comes from.

Now that the front shaft couplings are in place, with everything off, try lifting ONE front tire and turning it - does it feel like its turning the drive shaft and more parts inside the tractor? If so, it points to something further back not being engaged. The outside 4wd lever may not be turning the shifter shaft inside far enough to engage the drive gear. Does the mechanism feel like its connected to something inside? Sometimes the 4wd lever gets bent, and no longer moves far enough. Worth a check before shipping the machine off somewhere.

 

[Alabama Tractor Pickers]

Finding this post/thread very helpful. I just bought a 2003 L5030 HST Cab that is leaking BADLY while parked. Was told the leak was fixed and then reappeared shortly after. I'm suspecting propeller seal too. Will start my own thread when I decide to dive into this project.