Differential, problem?

[Raudermaster]

So, I laid on the ground today just to see what I gotta do to install my PHP control arms, and I happened to notice a "black" substance on the backside, on the bottom and in the front of my diff. WTF is it??? Please tell me I don't need to have the axle thingey done? I will get pics tomorrow morning so you guys can help me. Although, this could be a good thing. I wonder if I can get my friend, who just happens to work at the dealer where I bought my car, to install 4.10's and say they came "stock" and warranty them.

[fastblackmerc]

You won't see the "axle thingy" on the diff. You'll see it on the rear wheels and/or the inside of the rear rotors. You prolly just have to tighten up the cover bolts or maybe the pinion seal is going.

[Raudermaster]

I figured that couldn't have been related to the axles, but could this be covered under warranty?

[Drock96Marquis]

If it's leaking from the front, around the pinion/companion flange - it's the pinion seal.


If it's leaking from the bottom, it's the diff cover. Most likely some one jacked up the rear of the car from under the differential and bent the cover's lip a little, causing a slight leak. You could try tightening the bolts, though.

If it is bent, pull the cover off, bend it back to shape, scrape off all old RTV, put a fresh bead all the way around and reinstall. You'll need 3 (will use ~2.25) quarts of gear oil and a bottle of friction modifier. Let the RTV cure for a bit before refilling. Optionally, install a gasket (ie Victor Reinz for 8.8" applications) in place of the RTV and you won't need to scrape RTV next time you pop the cover off ;)

[Drock96Marquis]

BTW - if it is bent, a few have had mixed success spraying down the leaking area with brake cleaner, then liberally applying RTV banging it back to shape a little bit and topping off the diff fluid.
I do not recommend this, but some say it's worth a shot.

Myself - it's not very hard to remove the cover so I'd just do it the 'right' way. Maybe order a new T/A or FRPP girdle cover to throw on at the same time so it's a worthwhile repair.



Hopefully it is not leaking from the pinion, as this is a much more involved repair procedure.

And don't overlook the bolts as fastblack mentioned.

[RF Overlord]

Optionally, install a gasket (ie Victor Reinz for 8.8" applications) in place of the RTV and you won't need to scrape RTV next time you pop the cover off +1 for the Victor Reinz...I just picked mine up at NAPA today...changing the diff fluid this weekend.

[Stranger in the Black Sedan]

I am guilty of jacking under the rear and bending the diff cover enough to cause a minor leak. It happens!

[Blackened300a]

I am guilty of jacking under the rear and bending the diff cover enough to cause a minor leak. It happens!

Guilty as charged.