Pinion still leaking

[BigCars4Ever]

A couple of months ago I notices my pinion leaking. Orderd a new Ford seal from the dealer and installed it. When I had the pulled the drive shaft off I notices a lot of fluid in the area where the nut is. I didn't think anything about it at the time and replaced the seal and buttoned it back up. Now it is leaking again and I can see it is leaking where the universal mounts to the plate! Is it normal for it to leak there? should I dissasemble it again and put some black RTV on the pinion before I thread the nut back on? I'm afraid if I do that it will change the torque of the nut. Any advice is appreciated!

[burt ragio]

Just had my pinion bearing & seal replaced. It was leaking & caused vibration.
The nut should be torqued to spec. I don't believe it has anything to do with pinion load.

[wannaMM]

Leaky pinion caused a "Dry bearing" failure on axle bearings that were less than a year old...I'm going to have to get in habit of visually inspecting for leaks every month, as it is an 11 year old car...

[Zack]

When removing the pinion nut, you are to count the visible threads before removal.
When re-installing either coat all threads with silicone or get a new nut. Install with the same amount of threads showing.

[BigCars4Ever]

I used a paint pen and market the nut and the pinion. Then I used a digital caliper to measure from the top of the nut to the top of the pinion. I'm going to drop the drive shaft and take the nut off and apply silicon. Why would a new nut not leak? Does it have a seal on it?

[Zack]

I used a paint pen and market the nut and the pinion. Then I used a digital caliper to measure from the top of the nut to the top of the pinion. I'm going to drop the drive shaft and take the nut off and apply silicon. Why would a new nut not leak? Does it have a seal on it?

Yes it does

[lifespeed]

Oil can leak past the pinion splines between the pinion and the yoke. RTV is applied to the pinion splines during final installation of the yoke, after correct bearing preload has been accomplished using a solid spacer and shims (not a crush sleeve).

While shortcuts to the proper pinion bearing preload procedure as described above can sometimes work, I have found the best approach is to do rearends "by the book". They take a lot of load and can easily tear themselves up if not done correctly.

[BigCars4Ever]

So I pulled the drive shaft tonight and I could see that the seal on the back of the pinion nut was messed up pretty bad. Put some rtv in there and tightened the nut back up. Should be good to go now.

[Logizyme]

Ford and Loctite both offer a thread-sealing low strength thread locker compound that can be used instead of a new nut, because your new nut might not match up perfectly with where your old one was.