I rear geared my jk about 15k miles ago. Why is my diff pushing gear oil out the vent. This issue had been happening for the past 1500 miles.

 

Well if the diff is getting very very hot the oil could be expanding or foaming forcing it out almost like steam.

Option2- u have overfilled and that is all that is wrong- best option btw

Option3- water has entered the diff and u are displacing oil for water---ur welcome!

 

x2...like he said and unfortunately you don't mention recently changing your diff fluids and being your gears were changed 15K ago and your not mentioning any noises or such my first thought would be option 3. Drain your diff and make sure all is good.

 

more than likely, you overfilled your diff. common mistake

 

I re geared and experienced the same thing. I changed the fluid myself and filled it til the fluid seeped out of the fill hole. Big mistake!!! I have a 3.5" lift and the pumpkin sits at a different angle now so that may be an issue too. It's about time to change the fluid again so this time I will put in the correct amount and hopefully I won't have gear oil puking out everywhere.