I had 4.10's installed by a very reputable performance shop, and my pinion seal is leaking....for the second time!
The first time they told me they must have accidentally knicked it or something. No big deal, they replaced it. Well this is the second one and it is still leaking. Could they have done this again or could I have a bigger issue? Its not a major leak, but you can tell the housing is wet with gear oil and every now and then a drop will form on the bottom of the diff.
It was fine before the gears...no leaks at all.

 

Did they use black rtv or a ****ty gasket?

 

I dont know what they used. Can you use rtv for a seal on that?

 

That's what you SHOULD use. Black RTV.

 

I think he means the actual pinion seal where the driveshaft attaches, not the differential cover which does use RTV.

The outside of my axle is always wet with oil, but not enough to form drips.

I would clean up the rear end real good, to make sure it's not residual oil from the prior leak. If it continues to leak, take it back to the shop.

 

Yea, def clean it big time first and see if its still leaking. A little oil can hang out in that area for a long time.

 

Yep, I just talked to them. They use rtv.

 

Yeah its the pinion seal where it attaches to the driveshaft. The entire housing is soaked in gear oil and the drops form on the bottom. I know its not coming from the diff cover.
I will clean it off really good again and see, but this was 2 weeks ago when they replaced the first seal and it was wiped down then. We'll see.
Thanks guys!

 

Sorry, no leaks on mine. Had 4.10s installed probably a year ago now..... As you know, rear-ends are finicky- hopefully they can get it together correctly for you.

 

My son had 4.10s put in his '04 GT by a good and respected Mustang shop. He had it back 3 times for pinion seal leaks. The last time they put in a Ford pinion seal instead of an aftermarket seal. Problem solved.

 

That's funny I was just thinking that, that they are using a NAPA seal instead of a Ford one. Gear oil is sneaky stuff too, the SLIGHTEST minute gap and it starts creeping out. I've had a few stubborn gear swaps with leaks on other hot-rods over time.

 

Mine leaked as well after doing the gears but not right away. It seemed like it didn't leak until after I put the one piece aluminum driveshaft on at at later date. I took it back and had the seal replaced and so far it's OK.

 

Mine started leaking about a month ago. I had it replaced and then the gears went. I don't think the pinion seal had anything to do with the other except that the shop that did the install wasn't very good.