My truck has been making a loud (and louder the faster I go) humming sound coming from the rear of the vehicile. I just looked under there and noticed that there is diff oil leaking from where it meets the drive shaft and it looks like the end of the axle at the drivers side wheel on the brake assembly. There is no oil in the driveway indicating a leak, but I can see the diff fluid leaking. A few months ago I took the truck into the dealership to have the E-brake redone and as part of that service they replace the axle seals and serviced the diff.

Can I take this to them and have them fix it under the warranty or do you guys think its a different issue? Can I tackle it myself? How much damage is already done to the gears and if its Ford's fault, how do I hold them accountable? Thanks guys!

 

Does the humming noise change if you're on or off the throttle?
The leak at the front of the diff is the pinion seal. Quite possible that you have bad pinion bearings. That's probably not a job you'll want to tackle as it requires a press, torque wrench, possibly a dial indicator etc.
If the axle seal is leaking again I would hope they would cover that under warranty. If they pull it apart to fix that you might want to have them check out the pinion bearings etc too to see what the humming is. It could also be an axle bearing.

 

I took it to the dealer and its one of the bearings. The seal is shot because of it. The seals and all that are covered under a previous repair warranty, but the bearing work is not. Once he told me it was the bearings and the scope of the work I knew it was beyond what I wanted to do myself due to time constraints, lack of special tools and the fact that I might screw it up. Thanks for the reply!