Why is my rear axle vent line leaking?

[PolarBear]

So the rear axle on my 01 F250 4x4 has started leaking from the top of the vent tube that goes up under the frame. I changed the diff. oil about 5,000 miles ago and that was about June of this year. I put on a Mag Hytec cover and put in Royal Purple, I believe is was 6 quarts that is the nwe total with that cover. Anyways, everything has been fine since then up until about a week ago when this leak began. Truck drives fine and there doesn't appear to be any problems with the axle. The leak has been putting a couple spots on the concrete about the sized of a half dollar and its running down the frame and also coating the shock. Any ideas on what could be causing this all of the sudden. The dipstick on the new cover isn't showing the oil to be high at all.

[Bad Night]

Wow , that's a weird one . Usually don't see anything out of the vent . It is for expansion and contraction only . Seems it would have to be clear full to the top to do that . Are you sure it's gear oil and not a bad seal or a pin hole on the shock ?

[PolarBear]

Ya its a weird one to me too. I also thought it would have to be full to leak like that. When I got home from work and noticed it leaking about an hour later, I pulled the hose off and nothing ran out, there was maybe only 2 drops lift in it. I sprayed it out and clean with brake cleaner but it was good. Definitely gear oil because its still kinda purple and smells like the gear oil.

[Bad Night]

Yea , no denying that smell . Man I am at a loss . Were you possibly on a big hill with that side of the truck aiming down hill ? I don't have a clue . I guess possibly a fluke , maybe some air trapped in it pushed out ? I have heard of that when filling , was told to be very careful when replacing axle bearings and seals to make sure air doesn't keep gear lube from reaching outer bearings . Were you towing ? Anything to get it really hot ? Hopefully someone else has an idea .

[PolarBear]

Ya thanks for the help anyways though. No towing or anything with it. it has leaked on 2 different occassions now that it started. I do go down a hill in my driveway right before pulling into the garage. The hill is about 75 feet long and elevation-wise, probably drops down about 15 feet or so. It just surprises me that it has just now started doing this. I do suppose that maybe the extra fluid in the differential, when it runs to the front of the axle could possibly cause this.

[Bad Night]

Yea, possibly a higher fill with the new cover .

[evo45]

That is a wierd one! The only time I have ever had anything like this happen is after going through deep enough water to fill the rear end. But if you checked it I have no idea. Good luck finding out what it is. Post back if you come up with an answer.

[evo45]

That didnt happen on my F250 though, it was on a Samurai that was a submarine.

[PolarBear]

Anyone else have any input or experience with this problem? The truck is highway only and is seeing about 130 miles a day during the week right now. Some days it won't leak a drop and the next theres oil dripping down from that plastic "V" at the end of the vent hose. Which in turn drips and blows onto everything behind it, shock, axle, spare tire. This is definitely not what I wanted to see coming from that expensive oil and cover.

[Joshyutah]

Mine just started doing the same, did you ever figure it out?