My '04 SCrew (5.4L, 3.73, two wheel drive) has developed a differential leak, spots my garage with a spot the size of a quarter every time I drive it. She's got 42,000 miles, and thus is oput of warranty. I'm thinking of just replacing the pinion seal myself, to see it that stops the leak (can't really see where it's coming from - there's oil all over back there. even on fuel tank heat shield).

Anybody got any tips? I'm guessing it's as simple as:
1. drop drive shaft.
2. pry/chisel out old seal,
3. tap in new seal,
4. refill with proper lube and friction modifier,
5.call it done.

Any thoughts?

 

My axle on my '02 showed signs of seepage around the diff. cover. Took it to the dealer and they pulled the cover off and resealed, and put in new lube after. There are 12 bolts, I had the 9.75 rear end. I just reread your post, oil in the front is probably the pinion seal.

 

If there is oil all over the place back there you may want to do some more looking to confirm that you do not have a leak somewhere else causing the oil to blow back onto your diff. cover and fuel tank heat shield.

A year or so ago I had a small oil leak from the oil pressure sending unit and while driving, caused oil to blow back to the rear diff.

I'm not saying that is what it is. I would just want to take a closer look before I started replacing anything.

 

I would clean up the entire area and wait for the first drips to form. Did you check the level of the oil in the axle?

 

Lube oil level in diff is OK for now; maybe a bit low, but not critical. Consistency, color, and odor of oil in leak indicates that it is diff lube, and not engine oil or trans fluid.

Pinion seal is a $20 part. Another $20 for lube and friction modifier, so for less than $50, I should be back on the road.

CW