front differential oil leak thru vent tube.

Are you sure it is the transmission and not the front differential? Is the trans over full? Has it been overheating?

I am sorry. Is the front differential from my 2002 Yukon denali XL AWD. And I have check it with the mechanic and he identify low oil level in the front differential. Otherwise no leakage thru the differential. Only from the ventilator tube of the front differential. in the end near the inside fender driver side.

That makes sense. Okay, if you are certain that the differential is not over full, you haven't taken if off road where water could have gotten in there, the most likely cause is the vent itself or the hose is plugged or bent causing excessive pressure to build up. Once enough pressure builds, it basically blows through the restriction causing gear oil to come out.

What I suggest is to first, make sure the diff is full. Then, remove the vent hose and vent and inspect them. Make sure all is clean. If the hose is good, replace the vent and that should take care of the problem.

Hi again. My mechanic did clean the tube but continue with the same problem. Can you change only the vent. Is the vent the tip of the tube??
My son ask me if the front differential is electric ?? And if it has a pump that can cause the back flow thru the vent tube>>? ?? If your suggestion fix the problem and I want to donate more to you how I do that??
Thanks

Don't worry about the donation. You already have,. Regardless, no there is nothing electric. Also, there is no pump. And yes, the vent is located at the top of the hose. It is a one way vent that should only allow air flow out and nothing in. That would be my first guess as to the cause of the problem.