1997 4.6L that twice in the last month has leaked diff fluid through the vent tube on the front diff. It does not do it while you drive but it happens overnight. I have not done anything with the diff in the last year or so. I have owned the truck for 6 years and have never had this problem. The leak was about the size of an average pancake on the garage floor. Not overly concerned about it, but would like any ideas on what is causing it. Thanks for the help!!

 

Are you sure it is coming from the vent tube and not the passenger side axle seal? Mine was leaking at the passenger side axle seal and the vent tube. I replaced the seal and it was still blowing oil out of the vent. I fixed that by replacing the rubber hose and installing a catch can from Summit Racing. Ford fixed this problem by moving the vent from the center of the axle tube to the flange that bolts to the center section. Their fix requires buying an updated axle tube.

 

I know it is coming from the vent because it is coming out of the rubber hose that ends above the passenger side wheel well. It then drips down onto the cv and lower control arm. My vent comes out of the axle almost at the point where the passenger cv bolts to the axle.

 

I first thought mine was leaking only from the vent. I made a temporary catch-can from an empty 1qt oil bottle...I drilled a hole in the cap large enough for the vent hose to enter, and another small hole to vent pressure. I then cleaned up the oil from the wheel well, drive shaft and suspension components. I discovered the oil seal located where the cv joint bolts to the axle was leaking.

 

I am positive it is leaking from the vent tube!!!!!!!

 

I have the same problem on my '06, except in the rear...I was told it was due to foaming of the fluid. Was told the only way to correct it was to put a better quality fluid in...FYI, I changed my read diff cover to Mag-hytec and put in some Valvoline fluid (only brand I could find quickly).

Craig

 

I have mobil 1 in the front diff. I havn't used my 4wheel drive at all lately either.