M59 front drive shaft leak.

[Hersheyfarm]

noticed hydro fluid leaking from the front drive shaft housing tube. Anyone changed one? This just showed up when I changed oil and added a little Hydro fluid because it was low. So I assume the fluid level was low enough to not leak from the seal oil I added because it seems to be a pretty good leak.

 

[kcender]

I had the front axle seal replaced in my L45 because fluid was running back the tube and out the drain in the bottom of the trans case.It was done under warranty but the dealer said it only took about a half hour to do.

 

[rScotty]

I had the front axle seal replaced in my L45 because fluid was running back the tube and out the drain in the bottom of the trans case.It was done under warranty but the dealer said it only took about a half hour to do.

Did replacing the seal stop the leak? I'm assuming that the oil came down from the front axle and not forward from the transmission end. All these modern compact tractors use pretty much the same front axle drive mechanism, and I'm glad you guys brought this subject up. It's one I've been wondering about - especially about the lube type and level and measurement method - ever since time I saw that axle type........back about 1975.

Back 40 years ago the manufacturer recommended that the lube for bevel gear drive front axles could range from light hydraulic oil to heavy gear oil - but without any explanation as to why or how a person should chose between such a broad range of dissimilar oils. Today Kubota uses that same front axle and with the same weirdly broad lube spec.....right along with the same lack of explanation. Darned if I can think of any reason why they do that, but they do.

So it's up to the owner to decide which one to use, and after deciding what kind of oil to use then next there's the whole problem of just how level does that axle need to be to measure the oil level? After all, the level is being measured way out on one end. What's happening down at the other end? When using the tractor, we all know that axle oscillates up and down like crazy. What does that mean for oiling? So with that in mind I pull out the dipstick and look at the hash marks showing a fairly narrow range for the oil level and now I've got even more questions.

I guess what I'm saying is I wouldn't be too quick to blame the seal if the oil was coming from the front axle and not the transmission. And I wouldn't worry too much about the axle seal even if it did leak a bit...especially if I'd just topped up the system with some light oil. BTW, with that large of a casting, I'd want to check the venting before even thinking about changing the seal. And also take a look at the front axle pivot play like the operator's manual says to do every 600 hrs. Play at that pivot creates a pumping action that could also eat up a seal and cause a leak. My M59 seems to want that adjustment about every 200 hours.

All in all, I like to run this kind of axle with the oil level at the bottom of the acceptable range rather than at the top. I think that Kubota's own spec has given us a lot of leeway here.
Enjoy,
rScotty.

 

[kcender]

RScotty,the seal replacement seems to have stopped the leak but I have only put about 40 hours on the machine since then.When the dealer took the tractor to fix the leak he had it for about a week.He said he could not get the drain pin to show any signs of leakage by running the tractor and was reluctant to split the tractor until he could verify the source of the leak.After speaking with Kubota they recommended the axle seal replacement.If I remember correctly they said the seals had been "upgraded" and the fix was to go back to the older type of seal.I keep a fairly close check on the pin and I have not seen any leakage around it since.I use UDT in the front axle for no particular reason other than that is what the tractors come with when new.As someone once said on here,if it can handle the stresses in the transmission it should be good enough for the front axle.

 

[Hersheyfarm]

well I split the drive shaft cover and slid both ends away from the front axle and the tranny. I also removed the weep plug and left it there over night. Not one drop came out. The puddle from the other night was about 6" and happened over night. I'm thinking I have a very small leak and the shaft cover has been holding the fluid and decided to leak??

 

[rScotty]

RScotty,the seal replacement seems to have stopped the leak but I have only put about 40 hours on the machine since then.When the dealer took the tractor to fix the leak he had it for about a week.He said he could not get the drain pin to show any signs of leakage by running the tractor and was reluctant to split the tractor until he could verify the source of the leak.After speaking with Kubota they recommended the axle seal replacement.If I remember correctly they said the seals had been "upgraded" and the fix was to go back to the older type of seal.I keep a fairly close check on the pin and I have not seen any leakage around it since.I use UDT in the front axle for no particular reason other than that is what the tractors come with when new.As someone once said on here,if it can handle the stresses in the transmission it should be good enough for the front axle.

Well, good on you and Kubota both - not only for having the courage to try something new....but the courage to go back to the old if it didn't work out. 40 hours...hmmm....probably not enough to know, but glad your dealer set you up with the preferred sea. My guess - and that's all it is - is that evenwhen the axle and tranny venting is good, all rotating shaft seals will eventually leak where the seal contacts the shaft. When a shaft seal gets to that age, it makes sense to take an educated look at the fluid range on the dipstick versus how much oil you like to run. And maybe look at the type of oil too.

I don't entirely agree....no, that's too diplomatic.....I don't agree at all with that statement on transmission vs front axle stresses.
But I also think that it doesn't make much difference what type oil we put in Kubota's heavy duty FWD axle on the larger tractors and TLBs. Maybe that's what the author of that statement meant. Because that axle just doesn't have many mechanical problems. If it has a problem at all it seems to be eventual leakage, but that's normal in that kind of construction. A little leakage around the non-pressurized shaft should stand a chance of being controllable with oil type, level, viscosity.
enjoy!
rScotty

 

[rScotty]

well I split the drive shaft cover and slid both ends away from the front axle and the tranny. I also removed the weep plug and left it there over night. Not one drop came out. The puddle from the other night was about 6" and happened over night. I'm thinking I have a very small leak and the shaft cover has been holding the fluid and decided to leak??

Hey Hershey. Good to hear you're still having fun. It could be what you say: that the oil level in the front axle just leaked down until it was below the level of the shaft and was held for awhile in the shaft cover. I had the same thing happen and the same shaft cover question you are describing with our old 33hp Yanmar. I ended up replacing the seal, and of course that will fix the problem at the source for awhile. Often a long while.

But today I'd probably first do some simple tests to get more info on just what is going on. First thing I might try is fill the axle back up to max with hydraulic fluid as before, collapse the shaft cover, and see what it looks like in the morning. Hmmm.....If you did that and it leaked, but then you did it again with the oil level sitting at minimum on the dipstick and it didn't leak..... how would you feel then?
rScotty

 

[Hersheyfarm]

The front axle is full, so its never lost any. After I used it yesterday and loaded on trailer I notice a small drip from the weep plug. So I guess I have a main shaft leak or front drive shaft leak.

 

[rScotty]

The front axle is full, so its never lost any. After I used it yesterday and loaded on trailer I notice a small drip from the weep plug. So I guess I have a main shaft leak or front drive shaft leak.

Bummer..... Hmmm.....It sure shouldn't do that. But maybe there's a way to live with it for awhile if it's from the Front Axle. Do you load in 4wd? How steep are the trailer ramps? Could most of the leaking be happening then? Maybe you could switch to the alternative 80/90 lube and only fill to the bottom mark? That might tell us something.

And on a different subject entirely but still on M59s. Have you tightened up that front axle pivot bolt play recently? I don't think that fore/aft movement has more than a minor role in any kind of leak, but on mine tightening things up sure sure did improve the way it went over bumps. Loosen the lock nut, take up all the play in the axle pin, back off one flat or a little less, retighten the lock nut and you're done. About the easiest thing I've ever done on the M59. Easier than putting fuel in the tank.
good luck,
rScotty

 

[number two]

rScotty-funny you should mention the front axle pivot adjustment.
Last fall I made that adjustment on my B3030 at the 400 hour service.
It took about two full turns to tighten it up on my pampered tractor.
Now I have a seep -hope I don't get shot down for using UDT.
UDT is/was original fluid for this unit.
Did not notice any difference going over bumps.
Thanks for reading!