Rear hub oil leak

[Cavedog]

Hello All

Is the hub leak in the photo from the cork seal, or something else?

Thank you
Rodger

 

[topo]

That a good size leak that been there for some time are you leaking any brake fluid ?

 

[Cavedog]

I have the remote resevoir for brake fluid. It does not appear to have lost any.

 

[topo]

I would take it apart and clean it and go back with new seals and check the vent on that axle .

 

[fpchief]

Pretty sure it is the cork that has failed. Be prepared to replace brake shoes too if oil soaked.

 

[Cavedog]

Thank you. I will try corks and check the vents.
I should have mentioned that it has MRAP wheels. Could the extra weight be the problem ?

Thank you

Rodger

 

[cattlerepairman]

No, the extra weight is not a problem. The wheel hub and seal design is. When you replace the cork (some do, some do not and use RTV instead) coat the cork in RTV before putting it in place. Leave the side of that axle jacked up over night to let the RTV cure without any gear oil creeping along. Assemble the next day.

The axle vent design is also...ancient. The spring loaded rubber gasket likes to stick and causes the housing to pressurize, helping gear oil go where it does not belong.
I recommend to replace the vent mushroom with a simple hose barb fitting, run clear tubing up to the frame rails with a loop in it to account for axle movement, and put a cheap in line fuel filter at the end that you zip tie at a convenient location at the frame rail. That way, the axle can breathe, you know the vent is water tight up to the level of the filter and it is unlikely to clog, ever.

 

[Cavedog]

Thank you, Cattlerepairman. I will try this before looking at the seals.

 

[fpchief]

No, the extra weight is not a problem. The wheel hub and seal design is. When you replace the cork (some do, some do not and use RTV instead) coat the cork in RTV before putting it in place. Leave the side of that axle jacked up over night to let the RTV cure without any gear oil creeping along. Assemble the next day.

The axle vent design is also...ancient. The spring loaded rubber gasket likes to stick and causes the housing to pressurize, helping gear oil go where it does not belong.
I recommend to replace the vent mushroom with a simple hose barb fitting, run clear tubing up to the frame rails with a loop in it to account for axle movement, and put a cheap in line fuel filter at the end that you zip tie at a convenient location at the frame rail. That way, the axle can breathe, you know the vent is water tight up to the level of the filter and it is unlikely to clog, ever.

I am doing the vent lines on my deuce and thinking about doing it on the M923a2 also. When I took a vent off for cleaning the other day, it had pressure behind it.

 

[Katavic918]

I have done all 4 rear hubs over the span of a few months due to leaks. The first one I replaced the cork and both seals, the rest just got the cork replaced. Upon inspection it looks like the cork is the main culprit. Also if your bearing nut is too loose it could also cause a leak. As for brake shoes. The drum is designed in a way that a hub seal leak should not contaminate them. Wouldnt be a bad idea to have a set while doing the job just in case. Also get some lock washers. Don't forget to repack your bearings. Finally, leave your axle out until you adjust the brakes upon reassembly. Oh, and like others have said, check the axle vent first.

 

[Cavedog]

Thank you, Katavic.
Where did you see the leak?

Rodger

 

[frank8003]

cork in keyway and/or considerable mess

 

[Katavic918]

Thank you, Katavic.
Where did you see the leak?

Rodger

Same place yours is. Dont forget new axle gaskets also.

 

[Mullaney]

No, the extra weight is not a problem. The wheel hub and seal design is. When you replace the cork (some do, some do not and use RTV instead) coat the cork in RTV before putting it in place. Leave the side of that axle jacked up over night to let the RTV cure without any gear oil creeping along. Assemble the next day.

The axle vent design is also...ancient. The spring loaded rubber gasket likes to stick and causes the housing to pressurize, helping gear oil go where it does not belong.
I recommend to replace the vent mushroom with a simple hose barb fitting, run clear tubing up to the frame rails with a loop in it to account for axle movement, and put a cheap in line fuel filter at the end that you zip tie at a convenient location at the frame rail. That way, the axle can breathe, you know the vent is water tight up to the level of the filter and it is unlikely to clog, ever.

And the great part about using the cheap in-line fuel filter is that protects the line from critters that would build in the line - blocking off the vent...

Smart money is to put it where you can see it during your visual pre-trip inspection. In a perfect world, all three axle vent tubes would terminate at the same place on the truck.

 

[frank8003]

and where was all the vents when She was built?

 

[NY Tom]

I got from McMaster Carr a small aluminum manifold, some pipe plugs and 1/4" compression fittings with inserts. Ran a flexible tubing line from front axle to manifold mounted on firewall. Tee from back axle to middle and then to the manifold again. I got one with some extra holes so I can pipe in the transmission and transfer case down the line if I want.

Used one of those cone shaped compressed air mufflers. So far so good. Even after cleaning those axle vents were not releasing the pressure correctly.

Also went to the remote brake reservoir and replaced the "tee" where the vent from the Master Cylinder used to come in with the air pack vent line with a flare coupling.

 

[Dipstick]

Looks too light to be an oil leak from the picture. Could it be brake fluid? You can usually feel the difference in viscosity with your fingers or see it on a paper towel. That vent tube extension modification advice is well taken. I drove my truck up to NY state one time. Stopped for a smoke and found the entire rear of my truck bathed in gear oil. Turned out to be the vent. The tiny little springs rust and the rubber discs do stick. I wiggle my caps a bit before driving. Thanks to all who posted the visuals. Great info!

 

[frank8003]

Looks too light to be an oil leak from the picture. Could it be brake fluid? You can usually feel the difference in viscosity with your fingers or see it on a paper towel. That vent tube extension modification advice is well taken. I drove my truck up to NY state one time. Stopped for a smoke and found the entire rear of my truck bathed in gear oil. Turned out to be the vent. The tiny little springs rust and the rubber discs do stick. I wiggle my caps a bit before driving. Thanks to all who posted the visuals. Great info!

There is much information in SS about the wheel cylinders, cups, and proper springs.

 

[Dipstick]

You know the more I look at your picture of the leak and stains on your tire, the more it reminds me of one of my own posts. I had a similar looking leak and stains on my front tires. I thought it was oil at first, but the liquid although oil colored, was almost watery . It turned out to be rainwater mixing with king pin bushing grease due to torn zipper boots. Now I know the rears don't have zipper boots obviously, but the tire staining sure does look the same as mine did. I'm really curious to know what you find out. Could you have water in your differential from driving through deep water? I know it sounds dumb.

 

[Cavedog]

I have never driven my deuce through deep water. Here in New Mexico even shallow water is hard to find. It feels and smells like gear oil.

Rodger