Rear differential vent leak

[PG.]

Looking for some insight for an ongoing problem. I will try to make a long story short. About two years ago I did a decent overhaul on the Jeep suspension and replaced the front axle with a curry high pinion 44 and kept the rear 44 and put 4.88 Yukon gears and an ARB locker in it. Had a local shop do most of the work which I wouldn’t normally do, but I didn’t have the time or the space so I just paid for it to get done which was the wrong choice . During the gear break-in everything went well no issues until about three months later took it on hour long drive mostly freeway speeds and when I got to the off-road park, realized I had rear diff fluid puking out of the vent at the top of the axle. It had blown the vent tube right off. what I found was the vent tube had somehow wedged itself between the body and completely pinched it off. I had to cut the tube to even get it out. I replaced with new vent tube and routed it in a safer spot so it won’t get pinched and still have it at the top of the fuel filler neck. I added more fluid to replace what was lost and drove again. This time it started puking out the top of vent tube right at the white valve. I took it to a another shop that was suggested to me since I was not going to give any more time or effort into the first shop that was pretty horrible. This next shop had to text look at it and it was an off-road specific shop. They said they couldn’t find any reasons why it doing it. The only possibility that I suggested was that the first shop did not over size or expand the oil passage/galley in the differential that I read needs to be done when you install the ARBlocker. They said it might help, but it might not do anything, but since they were there, I had them go ahead and do it anyway. It’s been running fine ever since about 8/ 9 months. I went to a Jeep show today when I got home I had fluid puking out the vent tube again. I can’t figure out what is going on. Any suggestions would help.

 

[Superjay5]

Sounds like you have too much fluid in your axle and it’s puking out the excess….

 

[PG.]

Sounds like you have too much fluid in your axle and it’s puking out the excess….

I really hope it’s that simple. I’m not understanding why it’s been fine for 8-9 months and just decided now it’s to much fluid.

 

[Ashim]

Maybe the oil drainage slot wasn't opened up enough or the gear oil is overfilled. What weight gear oil are you using? Sounds like on a sustained high speed run, the gear oil is filling the tube quicker than it can return to the differential.

 

[Richard Mccullough]

If it’s still puking fluid after all that, maybe double-check the diff isn’t overfilled, especially if it was warm when you last topped it off. Also worth checking if the breather valve itself is clogged or faulty , even new ones can go bad or not vent right under pressure.

 

[PG.]

Maybe the oil drainage slot wasn't opened up enough or the gear oil is overfilled. What weight gear oil are you using? Sounds like on a sustained high speed run, the gear oil is filling the tube quicker than it can return to the differential.

I guess I’ll keep driving it until it stops just hope there’s enough fluid left to keep the gears alive. Yes it does seem to be high speed or hwy driving is when it has problems. Unfortunately I have to drive it to the trails and back.

 

[PG.]

If it’s still puking fluid after all that, maybe double-check the diff isn’t overfilled, especially if it was warm when you last topped it off. Also worth checking if the breather valve itself is clogged or faulty , even new ones can go bad or not vent right under pressure.

I will further inspect and probably just replace the vent check valve. Entirely possible it’s bad. I honestly overlooked that.

 

[PG.]

So back to it. Since the last post I replaced the white vent breather and adjusted pinion angle which needed to be done. No leaks until this weekend. Again drove about 1 1/2 hours on the freeway to get to a trail and back home. Found axle seal leaking again out the driver side rear. It’s been about 700 miles. Fluid level is about 3/4 inch down from fill plug. The pumpkin felt pretty hot when I got home but didn’t put my infrared temp gauge on it. I don’t know why my rear axle is building so much heat/pressure only on the freeway. Where would you guys go from here? It’s definitely not overfilled and vent tube is not clogged.

 

[macleanflood]

So you're absolutely 100 percent sure the tube out of the axle isn't clogged?

I guess I'd pull the dif cover and run a pattern and start inspecting the insides.

-Mac

 

[OldBuzzard]

Stock diff cover or aftermarket? If aftermarket, is the fill hole higher than stock?

 

[PG.]

Stock diff cover or aftermarket? If aftermarket, is the fill hole higher than stock?

Stock cover

 

[Sayantsi]

Kind of sounds like too much oil and frothing, and maybe oil getting into the tube and vacuum holding it up, so it just keeps going up and eventually spilling out. Maybe try a larger diameter vent tube?

 

[PG.]

So you're absolutely 100 percent sure the tube out of the axle isn't clogged?

I guess I'd pull the dif cover and run a pattern and start inspecting the insides.

-Mac

Yes . Iv checked and rechecked a few times. Had my son stand up by the filler neck while I blow compressed air through the tube after I removed it from the vent bolt.

 

[PG.]

Kind of sounds like too much oil and frothing, and maybe oil getting into the tube and vacuum holding it up, so it just keeps going up and eventually spilling out. Maybe try a larger diameter vent tube?

I can fit my pinky in there and it is about 3/4 of inch below the fill plug. Could it still have too much and wouldn’t that puke it out the vent hose instead of pushing out seals.