Clueless On Axle Seal Leak

[Subzero]

I'll start from the beginning which was when I bought the truck.
As soon as I bought it I had to get a state inspection at my Ford Dealer. It failed for the rear passenger axle seal leaking and was replaced for $219. Months later I discovered brake problems and I had my neighbor who is a great mechanic look at it as I was puzzled. He discovered that the passenger side axle seal had leaked and ruined my brake shoes causing weak brakes ( my master cylinder was also bad too). He then replaced it and the axle didn't leak for about a week. I showed him again and we thought that the clogged axle vent tube might have caused all the leaks so he took it back and replaced the seal and vent again. That was last week. I checked today and turns out it is leaking again. It just started leaking as I check a few day ago and all was well. Does anyone have any idea what could be causing the leaks? I'm stuck on what may be causing the seal to leak? This is the only big issue I've had with the truck the whole time I've owned it. Thanks for any info

Edit: I park the truck on the curb so it sits on a slight incline. I would think the axle wouldn't leak because of this but I thought id mention it.

[ultraranger]

Does the axle have wear grooves on it, in the same location as where the lip of the axle seal rides on the axle?

There MAY be a redi-sleeve available to sleeve the axle journal, where the seal makes contact with the axle.

If not, and if a grooved axle is the cause of the continual leak --even after several seal changes, your only other option would be to obtain a good replacement axle.

IF the axle does not have a seal groove in it, then possibly the wrong axle seal is being installed. ...another possibility is the seal is right but improper techniques are being used when installing the axle shaft, causing the seal(s) to prematurely fail.

When reinstalling an axle shaft, DO NOT let the full weight of the axle drag across the seal as the axle is being installed. Apply a light film of gear oil on the rubber portion of the seal, prior to installing the axle. While installing the axle, hold the weight of it up as the axle is slid into the housing. Letting the full weight of the axle drag across an axle seal, --particularly a dry one, greatly increases the chances of putting very small gouges or tears in the seal that will make it start leaking soon after installation.

[Subzero]

even after several seal changes, your only other option would be to obtain a good replacement axle.

I don't really want to think of that

Thanks for the tips. Next time I talk to ny neighbor I will ask him if it was grooved inside or other wear was noticeable. A new axle is not an option financially at this time so I really hope there is some sort of sleeve if I need one. I will be sure to search around. You'd think there might be one as its a common 9 in rear right? I really like this truck and I don't want to have to get rid of it after all I've done to get it the way I want it...

[1972hiboy]

The seal gets pressed into the hub and the seal rides on the spindle not the axle itself. I had mentioned in a prior post to you that a groove can happen after years of riding on the same spot. you can set the depth of the seal into the hub. instead of pressing it where it has been in the past you can set the seal deeper or shallower in the hub giving the seal a fresh surface to ride on. If a redi-sleeve is available thats a plus but you can work with what you got. there is alot of give and take in that hub, and like what was stated by ultra lube the seal and riding surface with oil or some lubricant prior to instalation so the seal does start out dry. im also assuming your not talking about the axle flange gasket? that would leak outside onto the tire and ground and would not contaminate the brake shoes....


it would help if I read your signature better and saw your working with a f100. I just assumed full floater.

[Subzero]

I don't know if he was putting the seal into the same spot but I'll try and see if moving it shallower or deeper helps this next time. The axle seal I'm talking about is leaking grease inside the drum and leaking out the back of the drum, then onto the tire. I do think that the seal has not leaked as bad this time but it could have just started also. Its definitely contaminating the shoes as the old ones that were changed out couldnt even stop the tire at idle speed by the time I had it changed, and I had noticed a very weak E brake pior to that. Thanks

[michael69]

You sure it is not the wheel cylinder leaking instead of axle seal?

[Subzero]

It seems to smell like axle grease and last time I checked the MC my fluid hasn't dropped any. I will be sure to check this time around- you never know.

[guhfluh]

I don't know much about the 9", but axle seal leak problems in Dana 70-80 trucks can be associated with overfilling. Even with new seals that are correctly installed, many people fill the diff until fluid comes out of the full hole and axle seals keep leaking. Filling until fluid comes out of the hole is actually incorrect and overfilled, and why they keep leaking. Parking on an incline could be aggravating the issue, if its overfilled already.

[ultraranger]

The end flange on the rear axle tube, where the axle bearing and seal is housed, has a ridge at the bottom of the end flange bore. There is no in or out placement (adjustability) for the position of the axle seal to get the seal's lip to ride on 'fresh meat' of the axle journal, if the current axle has seal grooves in it.

If the axle seal is not fully seated/bottomed out flush against the ridge inside, it will keep the axle from fully sliding into the axle housing when the axle is bolted back in.

I don't know what tools are being used to install the seals but if they are not evenly distributing the force across the seals as they are being installed, it could be distorting them, which could cause it to leak. If the garter spring on the back side of the seal is knocked off while installing the seal, this can make them leak too. The small, circular spring puts tension on the rubber portion of the seal to keep the seal tight around the axle journal.

A Ford 9-inch rear requires 5 pints of gear oil. This means you will need (3) bottles. It will take all of (2) bottles and half of the 3rd bottle to fill the rear end. If you have a Ford Limited-Slip or Ford Traction-Lok differential, you will need 4 oz. of friction modifier. Pour the friction modifier in 1st before you begin adding the gear oil. Fill to the bottom of the fill hole, as per the Ford shop manuals instructions. If you have an open (single track) differential, the friction modifier will not be needed.

Parking on an incline shouldn't have any bearing on the seals leaking oil. If the seals are doing their job (sealing), the
angle/pitch of the truck will make no difference.