1996 sterling 10.25 pinion seal problem
 

I have a 96 7.3 f250 with 133,000 miles. In may of 2005 20,000 miles ago I had the pinion seal leaking. The shop changed the pinion seal and flange yoke. Now the seal is leaking only after driving an hour on the highway. It doesn't leak around town. I can go weeks with no leaks in town. The vent tube is clear. It's not leaking in front of nut. The fluid level was a little high. I opened the filler plug and let it drain (aprox.3-4oz.) until it stopped. Still leaking from seal. There is no play in the yoke. I bought new parts from ford, a seal, companion flange and nut. Should I replace all 3 parts. Everyone recommends different. how many times can you reuse nut? I figured flange as extra precaution. I was told to coat outer edge of seal with permatex non hardening sealer. Also permatex between the washer and pinion flange yoke mating surfaces and loctite the old nut (not to use new nut). WHY WOULD THE NEW SEAL LEAK WITHIN 20,000 MILES & 7 YEARS...not being used enough. I live in north central fl...cold winters hot summers. Thanks for any input you might have

Cold winters, florida?? kidding...kinda

Just checking, but do you have any noise back there, like a pinion bearing out? If you bought all the parts, might as well use them. My guess on why the seal leaked if all else is ok, maybe just a cheapo piece of crap.

No noise in rear and the companion flange has no play. When mechanic change it he used ford flange but ford sent wrong seal so he used aftermarket seal. A few friends said to use the old nut. I'm in Ocala it gets as low as 17 degrees and high of 99. Not as cold as north though.

I was just kidding on the weather. Although it ranges from -30 to 110 here. Anyway, I guess I wouldn't be afraid of using the old nut either, but am wondering why they said not to use the new one?

I've reused the old nuts before, never seemed to cause any problems, but I don't see any reason not to use the new one either. I agree with Darin, probably just a bad seal. 20,000 miles in 7 years, I'm assuming the truck sits a lot. That can do it to a cheap seal.

Thanks.... I'm semi retired and only drive it now 1-2 times a week. I'm thinking now of just changing the seal only. What permatex sealant is non hardening for this application?

I've always used RTV Gasket Maker.

Thanks for info>>.

check for clogged vent in the rear diff, mine was and caused mine to leak, replaced seal it was fine for like a month and then started leaking, cleaned vent and cleaned everything been a year now

The vent check was the first thing I did as stated in original post.

On the old nut do I use the blue loctite (removable) or the red (permanant)?

I'd use the blue, it'll hold just fine. If you use the red you'll need to take a torch to it to take it loose and I wouldn't wanna have to use a torch that close to a new seal.