I have an m9000 4wd and the front wheel case cover seal started to leak. When I unscrewed the filler plug the oil came squirting out under pressure. I just serviced these last spring and the oil was to the threads on the filler as it called for, but when I opened it just now I had at least a cup of oil squirt out. There doesn't appear to be any sort of vents on the front end at all that I can see.All I can think is that the oil from the front diff is getting past the seal on the diff yoke shaft and building pressure in the case cover ?? Any ideas ??
M9000 axle seals
- Thread starter kjbkubota
- Start date
All three compartments in the front axle are interconnected and fluid will slowly migrate between them depending upon the slope the axle is operating at.
To Vent or not. Some axles are vented others not. The pressures which can build up in a properly filled axle are minimal. As a comparison consider the engine crank seals dealing with 50 to 60 psi oil pressure.
Vents can allow a constant in and out of air containing moisture and in some designs are not used.
Dave
To Vent or not. Some axles are vented others not. The pressures which can build up in a properly filled axle are minimal. As a comparison consider the engine crank seals dealing with 50 to 60 psi oil pressure.
Vents can allow a constant in and out of air containing moisture and in some designs are not used.
Dave
Actually Dave, on a M9, the outboards are segregated from the center carrier by a seal in the end of the axle case at each end so the outboards oil is separate from the main axle. Having said that, I had a bad outboard seal on the left side and replaced it last year but intermixing of the oil isn't the end of the world other than the fact that the oil level in the axle case (at the level plug when full) will be higher than the outboard level plug so if the case seal between the outboard and the main axle case is leaking, removing the outboard case fill plug will result in oil overflowing the filler port.
Not gonna squirt out, but it will overflow. Not hard to replace the seal, if I remember right you take the tie rod mount off and remove the 6 capscrews that secure the outboard to the axle case and remove the outboard as a complete assembly but, it's heavy and a two person job. There will be the seal and a shim inside and the seal is an easy install. Rather than pop the tie rod end, I just unbolted the casting the tirerod mounts to and moved the assembly out of the way.
Far as I know, the front axle and outboards are not vented on the M9's.
I don't use UDT in my front axles, I use Shell Spirax 85-140 gear oil. Always have from the first change.
I'm sure UDT/SUDT is fine as well but I feel more confident with an extreme pressure gear oil in the front axle versus the Kubota oil. Mine take a lot of abuse.
There ain't no 'diff yoke shaft'. It's unequal length half shafts from the center planetary to the outboards. When you pull the outboards, you can pull the shafts out if you want to. In fact, I recommend that when putting in a new seal anyway. I think the seal was 9 bucks at my dealer. You do need to coat the mating surfaces with 3 Bond and make sure the locating dowel is in the correct spot when you put the outboard back on as well.
Not gonna squirt out, but it will overflow. Not hard to replace the seal, if I remember right you take the tie rod mount off and remove the 6 capscrews that secure the outboard to the axle case and remove the outboard as a complete assembly but, it's heavy and a two person job. There will be the seal and a shim inside and the seal is an easy install. Rather than pop the tie rod end, I just unbolted the casting the tirerod mounts to and moved the assembly out of the way.
Far as I know, the front axle and outboards are not vented on the M9's.
I don't use UDT in my front axles, I use Shell Spirax 85-140 gear oil. Always have from the first change.
I'm sure UDT/SUDT is fine as well but I feel more confident with an extreme pressure gear oil in the front axle versus the Kubota oil. Mine take a lot of abuse.
There ain't no 'diff yoke shaft'. It's unequal length half shafts from the center planetary to the outboards. When you pull the outboards, you can pull the shafts out if you want to. In fact, I recommend that when putting in a new seal anyway. I think the seal was 9 bucks at my dealer. You do need to coat the mating surfaces with 3 Bond and make sure the locating dowel is in the correct spot when you put the outboard back on as well.
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Flip.
I accept you are correct.
I did watch a Messicks shop video where I picked up the comments I made.
As long as there is a cushion of air in either compartment, I do not see the pressure rising to a height where good seals would be breached.
Dave
Having had mine apart, I know and I had the guidance of my Kubota mechanic at the dealership and he said, just take it apart and replace the seal, which I did.
The part about the fluid 'squirting out' I don't buy however. Seems to me to be a bit exaggerated. There might have been a bit of internal pressure (warm axle), but I doubt it squirted out.
The outboard to axle housing seal can fail because of age and runout in the half shaft. The seal gets old, the seal lips harden an d it can no longer seal to the half shaft effectively, so it leaks. Not a big deal to replace. When I removed mine, the seal lip was rigid. The new seal was pliable. I suspect at some point in time, I'll have to replace the opposing seal as well but maybe not. I had Dennis rebuild the opposing side (needed a new king pin and pressed in bushings) so I suspect he replaced that seal as well as he had the outboard off anyway. I know he renewed the hermetic seal between the upper and lower halves of the knuckle.
Even if it leaks and allows the center section fluid to run into the outboard, nothing will fail (other than when you remove the level plugs on the outboards, the fluid will run out because the level plug is LOWER than the center axle section and liquids always seek the lowest level), but, there is still enough fluid in the center section to lubricate the ring and pinion and the ball bearings that support the half shafts. Simple (but not perfect procedure) is to fill the center section, allow the fluid to fill the outboards until the it flows from the level plug(s) and button it up. Problem with that is, if only one side has a failed seal, the other side will need changed anyway (fluid). Determining which side is the trick but also simple as well
Pull the outboard level plugs. Whichever one flows lubricant, that side seal has failed. In my case it was the right side.
Kind of a strange design. I would have eliminated the outboard seals and level plugs entirely and filled everything via the center section fill and level plug. Only drawback to that is the outboards are essentially over filled while the higher center section is under filled.
Pull the outboard level plugs. Whichever one flows lubricant, that side seal has failed. In my case it was the right side.
Kind of a strange design. I would have eliminated the outboard seals and level plugs entirely and filled everything via the center section fill and level plug. Only drawback to that is the outboards are essentially over filled while the higher center section is under filled.
Yes you are right all three have there own oil resevoir . I have been running udt in mine as my dealer said it was best ??The shop manual says either gear oil or udt. I am thinking the pressure must have come from oil escaping past the diff seal into the outboard case, and yes it squirted out all the way up my arm when I pulled the plug. The diff is a bit low on oil now and as I said i just serviced them in the spring. I am just wondering though if I should change the outboard seal when I get in there or was the pressure just pushing the oil past the seal. As you know getting to the outboard seal is a lot bigger job, also if I were to change to gear oil is just draining the udt out good enough and changing over or will it have to be cleaned out somehow,in other words are they going to be compatible if there is residual udt in the cases. Thanks for all the info by the way the shop manual does call them diff yoke shafts but I agree with you there just half shafts..
Changing the 'hermitic' seal between the upper and lower outboard knuckles is a different animal entirely. You need to remove the outboard entirely (makes it easier) and pull the top cover (where the grease fitting is and extract the through pin and then remove the seal. They don't usually leak unless there are mitigating circumstances (usually the internal bushings are worn oval) and that causes axial play in the knuckle assembly which in turn causes the seal to leak. having said that, not only does removing and replacing the bushings require a special Kubota tool, but seating the seal properly also requires a special Kubota seal driver tool. I think, If I were you, I'd take the entire outboard to your dealer and let him rebuild it, they have the special tools. Parts are not that much but again, you don't have the tools necessary for a successful job.
Easiest way to determine play is grab the hub (wheel off) and lift it. If you feel any movement at all, the bushings are worn oval.
How I'd do it, but your mileage and my mileage are different.
Easiest way to determine play is grab the hub (wheel off) and lift it. If you feel any movement at all, the bushings are worn oval.
How I'd do it, but your mileage and my mileage are different.