Leaking rear axle seal

I got our new motor home at the end of March. Some time in June, I noticed oil streaking on the right rear wheel. A quick phone call to Tiffin and I learned that this is usually not something to worry about and I should get it taken care of when I had the coach in for service. A streaked wheel turned into a puddle of oil in the wheel. We were touring the Canadian maritimes and I found a repair shop in North Sydney, Nova Scotia to get the repair done. The technician removed the right rear axle, cleaned up the hub and the axle flange, pronounced the OEM gasket that was used as 'crap' and proceeded to put a new, heavier gasket in its place. He cleaned the wheel and center dress 'can' of all the residue oil. He checked the rear end oil level. It was so full, that oil leaked out when he pulled the plug to check it.

With a week or so I noticed some oil streaking on the wheel. A lot of it came from the lug nut covers, which were not removed and cleaned. After a while, I noticed that some of the oil streaking appeared to come from the center can. I was headed to Red Bay and figured I would get it inspected by a factory tech. At the beginning of September, we arrived in Red Bay and the tech pulled the can and didn't find any issues with the repair. He did break off a piece of some of the gasket sealant that had oozed out from between the axle flange and hub, though. When all repairs were finished, we headed to Dallas to visit with family and friends. Imagine my surprise when we backed into our site and I noticed oil puddling in the wheel again.

Because of other issues encountered during the warranty repairs, we ended up going back to Red Bay. The mechanical tech that had inspected the seal got to be the guy to look at it again. When he and another tech removed the axle, they could find no evidence of the gasket that had been installed by the Nova Scotia tech. Even when I showed them a photo of the gasket on the hub while the repair was being done, they were rather dismissive of it. As far as they were concerned, the factory didn't install the gasket correctly. Neither did the tech in Nova Scotia. They put a new gasket and sealant and cleaned the can and wheel again. I accepted their pronouncement and headed back to Dallas. While there, I washed the coach and cleaned any residual oil left of the wheel that may have seeped out of the dress items during the trip.

We headed out from Dallas to Grand Junction, CO. I inspected the wheel again and imagine my surprise when I discovered more oil streaking on the wheel, some of it coming from the center can again. I called chassis support in Red Bay. The tech there said he would check with some more seniour techs and with Eaton, the axle manufacturer. He called back the next day and gave me a step by step procedure on how to replace the axle seal. (i know the Nova Scotia tech did it the way it was described to me, other than the torque on the nuts because he gave me a higher torque value than was in the service manual, 190 vs. 170 ft. pounds). Eaton also said to use new nuts and washers, which the Nova Scotia guy did. I wasn't present when the Red Bay techs installed the nuts, so I don't know if they used a torque wrench or new nuts.

During my conversation, I said to the tech on the phone, 'So, the manufacturer performed a faulty installation, the first repair shop in Nova Scotia performed a faulty installation, and the factory guys in Red Bay also performed a faulty installation. Does that seem reasonable to you, because it doesn't seem reasonable to me'. He sort of agreed with me, but that was the end of it.

I have diagnosed many items in my time. Experience has taught me that if you have a problem and repair it the same way three times, you are fixing a symptom, not the problem. If I replace the gasket a fourth time, I have no doubt that it's going to fail again. My problem is that I don't know enough about heavy duty trucks to know what to check for. A couple of people I spoke to that have experience with this type of repair told me that they usually don't even bother with a gasket. They clean up the mating surfaces and use some RTV to seal them.

Can anyone offer any suggestions for what could be causing these failures?

I would be suspicious that one of the surfaces is not true.  I would remove the axle and clean both mating surfaces.  I would then reinstall the axle with the surfaces dry and take a feeler gauge and go around the circumference and check the gap in several spots and see how much variance there is.  If the face on the axle is not true with the shaft you may be smashing the gasket on one side and not making contact on the other.
I agree with you that I doubt that 3 different installers made the same mistakes.

Good advice from boatbuilder.
The first tech pulled the plug and oil leaked out? How much oil leaked out? Did he let it run out to the proper level, or just jam the plug back in? The rear may be overfilled, and that can cause issues also. Has anyone checked to ensure the breather is clear?

Rear housings are vented so they don't build up pressure inside the housing as things heat up. If the vent is plugged pressure could be building up causing the leaks.

kdbgoat said:

Good advice from boatbuilder.
The first tech pulled the plug and oil leaked out? How much oil leaked out? Did he let it run out to the proper level, or just jam the plug back in? The rear may be overfilled, and that can cause issues also. Has anyone checked to ensure the breather is clear?

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While you have it out, I would also have the areas PT (die penetrant) inspected.  You could have a crack in one of the castings and it won't show up initially until it gets hot and the crack opens up. Just a thought.

Some axles have cone shaped spacers around each stud to keep the axle from from moving back and forth against the hub. Could it be the cone spacers are missing, causing the gasket to get rubbed away?
I have successfully used Permatex "Gear Oil RTV Sealant" instead of gaskets on axles. Just a little food for thought.

rls7201 said:

Some axles have cone shaped spacers around each stud to keep the axle from from moving back and forth against the hub. Could it be the cone spacers are missing, causing the gasket to get rubbed away?
I have successfully used Permatex "Gear Oil RTV Sealant" instead of gaskets on axles. Just a little food for thought.

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I watched both repairs. There was a washer and a nylon lock nut on each stud. I don't recall seeing a tapered dowel. When I called Eaton, the tech support guy mentioned something about a tapered dowel, but I really didn't know what he was talking about. If the tapered dowels were missing during initial assembly, I would assume subsequent repair techs wouldn't be looking for them if they weren't in the assembly, would they? If they were missing, the axle scraping back and forth on the hub would explain no evidence of a gasket at all, wouldn't it?

Do all Eaton axles use tapered dowels?

When I get it serviced again, I'll also make sure the oil level is right, have the tech check the clearance between the hub and axle flange, and make sure the breather tube is clear.

That''s a few things. It's too bad the factory could suggest these items.

Thanks guys!

Is there a chance you could take it to Eaton themselves?

There is something basically wrong with that particular rear axle assembly on your coach.

mrschwarz said:

Do all Eaton axles use tapered dowels?

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No. All Eaton axles do not use centering cones. Haven't seen one in years. Sure your fill plug on hub isn't loose or cross threaded? I've heard of people who pulled axle and replaced gasket when it was a loose plug. I came across a cross threaded plug one time. Had to re-tap. Aluminum hub, steel plug. 

jubileee said:

No. All Eaton axles do not use centering cones. Haven't seen one in years. Sure your fill plug on hub isn't loose or cross threaded? I've heard of people who pulled axle and replaced gasket when it was a loose plug. I came across a cross threaded plug one time. Had to re-tap. Aluminum hub, steel plug.

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There is no plug in the hub that I have seen. The flange on the end of the axle covers the entire hub. Also, if it was a loose plug, wouldn't replacing the gasket have no effect on the leakage? Replacing it stopped the leak temporarily.

jubileee said:

No. All Eaton axles do not use centering cones. Haven't seen one in years. Sure your fill plug on hub isn't loose or cross threaded? I've heard of people who pulled axle and replaced gasket when it was a loose plug. I came across a cross threaded plug one time. Had to re-tap. Aluminum hub, steel plug.

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Thanks Jubileee, I haven't been into any thing heaver than a Dana 80 in many years. Was unaware that the tapered cones were history on the heaver axle assemblies. It's been so long that I couldn't even define them correctly.

So here's what's happening so far. I just got off the phone with a Dana Technical Services Manager. The original gasket was a thin paper one. Both replacements used thick gasket material with RTV on both sides. The first repair used new nuts and washers and a torque wrench. The second one didn't. According ro Dana, that's virtually guaranteed to leak. There's way too much compressible material between the axle flange and hub. The factory procedure is clean up the surfaces, use the correct, thin gasket, use new washers and nuts, and use a criss-cross pattern and a torque wrench.

I made arrangements with a local shop to work with Dana for parts and hopefully, the repair will be done next week. The Dana guy said he would make sure the Tiffin Service Center learned the proper way to fix this.

By the way, the Dana guy said that they still used tapered dowels for some applications, but this one doesn't require that much. He also said that a thin coat of RTV INSTEAD of the gasket will give a good seal. We'll motor down to Mesa, AZ and around Arizona this winter and see what happens next.

Thanks everyone for your comments.

Thanks for the update, glad to hear it may be solved soon!