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how to keep heart when leaks keeps leaking

It's taken me awhile to feel like talking again. The second repair to the 'Leaking Rear Axles' on my 78 150 held for a few days then gave way.
I'd put black ATV sealant all around the seal itself, all around the inside of the axle housing where it sits, on the outside where the axle flange pulls it all against the axle housing flange and on the new gasket I put between the brake backing plate and axle flange. This is after having the old bearing and seal removed, new ones reseated and my first reinstallation a month ago.
So now all I can think of doing is to pull it and put MORE and A LOT of this or maybe another sealant and try it again.
Thought I'd let those of you who tried so much to help know what was going on and thank you again for all your advice.

jim in nc
Don, I'm thinking you're in the ballpark. There is a little of what looks like maybe rust damage, some decay of the metal in the axle housing, right there where the seal sits. Do you think if I put that sealant on thicker it might take up the slack?


Texas Chapter Leader
Hard to say... I have done little work with axle seals and what not, but i wonder if you could double up on gaskets, and add some rtv, i think the black is the good stuff but i know red is pretty good too?

I always used rtv for seals like your dealing with. Seems i generally used black though... How bad is the leak now?
Just been through the same exercise with my friends k2500 ch*v
- after trying different silicon's and various homemade gaskets and even heavier oil + trying to clean the rust off the housing we gave in and after some searching we found another housing to use ...... no more leaks.

Maybe go down to your local wreckers and nab yourself a new diff - i think you'd save yourself a lot of grief that way
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Don and Mark,
Well a buddy is coming over tomorrow morning, bright and early . . . way before I'm usually ready to do ANYTHING . . . He's bringing another tube of the black RTV and we're going to take another look.
It's not leaking real bad, not as bad as it was when this all started, back then the inside of my tire was just soaked and there was a puddle on the ground.
Now it's just a drip at the bottom of the brake drum.
I will admit to entertaining the notion that the axle housing could be worn, but I still want this to go right and needing a new differential is way south for me and my pocket.
I'll let you guys know what's what soon as I know.
Thanks for your input.



Texas Chapter Leader
Any way you might be able to file it down to cut out the pits? Depends on how bad it is and how good of a file you have? It could fix it, or it could make it worse... I would use it as a last chance kind of gig..


Nov.TOTM 2012 / 2012 TOTY
this is going to be difficult to stop..your axles may be grooved also but its impossible to check without removing the bearing & seal which i believe are pressed on. as far as the pitting in the housing my suggestion would be to use J B weld but it will need to setup overnight for maximum strength before you will have to clean the surface & remove any oil film around this area. mix it up let it setup for 15 min then apply it like bondo & fill in the pits,get it as smooth as possible & let it far as a sealant goes try the Permatex Grey in the grey tube.this stuff is exccellant to use around oil & grease.sometimes in time the oil will break down the rtv & other sealants.this grey stuff withstands the oils & will not break down to it.if your gonna go through the motion again its worth a shot.good luck! Bob
To me the fix would depend whether it was leaking from the mating surface between the diff housing and the seal or between the axle shaft and the sealing portion of the seal. I am not sure what is leaking from the problem as described.


California Chapter member
Isn't it possible to have the surface re-surfaced, or planed smooth again to take out the nicks? I would think it would have to be all the way around the contact surface, and I would hope that the seal would be pliable to take up the slack?... Just thinking out load here. Good luck!

You know, Truckin' AK, that's a good point. I tried to determine this when I had the axle on the work bench (standing upright) by filling the bearings with diesel fuel. The fuel didn't seem to be leaking through for the three of four minutes that I tested it, but I don't know if that was enough to know for sure. When the axle is in place there is a flange called the "bearing retainer" that makes it very difficult to see what's going on with the outboard side of the seal there. Any ideas on how to determine this while the axle is in place?
Thanks for the feedback.

Jim in NC
Have you checked the axle vent? If it's plugged up, a very common problem, when the axle gets warmed up it will build up enough pressure to cause a leak on an otherwise good seal.
To check the vent, disconect the hose and unscrew the vent from the housing. Inside the vent, the actual hole is relatively small. I've had to run drill bits through them to clear them out, so they do get plugged up pretty tight.