8 3/4 leaking diff fluid into Brakes

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str12-340

str12-340

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Looking for help with this persistent problem. On the left side of my Dart, differential fluid leaks into the brakes. I have had that axle (actually a different axle) rebuilt with all new bearings and seals and replaced the seal in the axle tube twice. It is better than it was but it still happens. Any suggestions on what to try next???
 
There are two seals for the flange on the shaft one metal and one foam.... Did you use both or just one???
 
Check to make sure that the vent is operational, and not clogged. I had this happen to a Dana 60 once, and it drove me nuts why it would keep blowing seals.
 
The inner axle seal (in the housing) is the only one that is designed to keep the gearoil inside the housing and not mix with and wash away the grease in the bearings.
If the bearings are adjusted too loose then the axles are riding 'higher' in the housing, causing the inner seal to become less efficient at the lower part and possibly leak oil onto the bearing(s).
Tightening up the axle-play could solve the issue.
 
There's an outer seal that, unfortunately, occasionally goes bad. Try checking the end play as stated above first. The annoying part is that the bearings need to come off the axles to change them.
 
Double check that it's not the brake wheel cylinder leaking. I too thought it was the axle seal (twice on different cars) Just a thought.Maybe.
 
Did this just start leaking or has it been always a problem?
Had an issue back in the day. Thought axle was bent. Changed axles, inner seal several times.
Assumed housing flange must be slightly bent. Enough to ride more on one side of seal consistently.
Was able to find a heavier duty tighter seal, leak went away.
 
str12-340 said:
Any suggestions on what to try next???
Click to expand...

Just a couple thoughts here.

Did the spring get knocked off during installation?

(When I put them in, I pack a little grease on the spring side.)

Did you cover the splines on the axle when installing it?

(The splines can actually nick the rubber around the axle allowing for a leak. It does require pulling the pig in order to remove what is over the splines.)

And don't let the axle 'hang' putting upward pressure on the seal, slide it in as far as possible leaving it a bit shy so the pig can be put back in.

One other thing of note, is sometimes there can be a small groove worn into the axle where the seal rides allowing for a looser fit, hence possible leak.
 
Thanks for all the suggestions - I will definitely be following up on some of these. I believe that Big Block Mopar is correct - that seal in the housing is supposed to control the diff fluid from getting out and into the bearing and brakes, the rest keep crap out of the bearing from the outside, not the housing tube. This hasn't always leaked but it has leaked after two housing seals have been replaced. I haven't tried the vent, but it makes sense and I will definitely get a new one and replace it. I can see how a poorly adjusted bearing would allow the axle to be pushed up into the seal creating a gap at the bottom. I wish there was a better way to figure out how loose is too loose beyond the dial indicator called for in the FSM.

Mycuda any recollection as to where the heavier, tighter seal came from????
 
When I adjust end play, I try to eliminate as much end play as possible. Adjust then tap both axles in the center to make sure there is not more than a few thousands end play. The original bearings are tapered rollers, any excessive end play, allows the axle to slip out of the cone and put extra pressure on the top of the tube seal.
 
You can create a "tighter" seal yourself too by grabbing a part of the surrounding spring, create an extra loop and twist it on its self so the spring now sits tighter around the seal.
 
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