I have a 1995 2500 CTD. Rear end started leaking at 40,000 mi. New seal, leaked again. Another new seal at 60,000. Held up until 110,000mi. Started seeping. New seal, drove 100 mi leaked again. Took it back, new seal, drove down to Ca, leaked again. None of this work was done buy the dealer, just my good ole mechanics. They have got no answer. HELP!!!

 

Wheel seal or pinion seal? Is the rear full to the bottom of the fill hole? It should be 3/8" - 1/2" below the fill hole, extra tends to end up on the brake shoes.

 

Fluid level is very important on these differentials. Most mechanics routinely fill them to the bottom of the hole instead of the recommended level. Many times they will quit leaking once fluid has leaked out to the correct level. Not too good for your brake shoes in the process.

Here are a few other sources of repeated leaks.
1) Make sure sealant is applied on the outside edge of the seal before driving it in so it doesn't leak around the edges.
2) Make sure the axle shaft doesn't have a groove worn into it where the seal rides. This happens when leaks are allowed to go on for long periods, dirt gets in the leaked fluid and acts like sandpaper on the shaft. Sometimes the seal can be driven in deeper or shallower to ride on a fresh part of the shaft. If this isn't possible a sleeve can be installed over the shaft with an oversized seal.
3) Rear bearing could be shot allowing the axle to wobble.
4) Clogged vent

 

Thanks for the reply infidel. I heard about the oversize seal but my mechanic has not. Where can you get one? The shaft is not grovved. Vent pipe is open. Brakes are OK so I dont think its leaking at the wheel seal, just dripping from the pinion seal. Thanks.

 

They're called Speedi-Sleeve, any auto parts will know what you're talking about. If you don't have a groove in the shaft you don't need one anyway.

If it's the pinion that's leaking repeatedly I'd say

1)the preload isn't adjusted right
2) bearing is shot
3) driveshaft is out of balance
4) all of the above.

 

You will need to determine were the leak is from.
1: spray brake kleen on entire seal area and clean and dry well
2:determine if the seal is leaking arround the pinion or the housing ( I jack standed the back end and ran it while I watched from below) If its the seal to the housing area a new seal installed with a good sealer should fix it up.
If its leaking between the pinion and the seal ~infidel~ covered it.
Its interesting how some of the seals lasted so long and some not?
I had a housing once that someone put a big groove in while improperly removing a seal and it took a while to see that the leak was comming from the groove and not the rubber seal.

 

It's amazing how little it takes to make a cover leak. I've ran into a couple Danas that leaked just because of a number stamped on the sealing surface of the diff.

 

Yeha, sometimes the simplest problems are the hardest to see