Leak where rear diff meets drive shaft

I noticed this on that back of the fuel tank. Smelled like gear oil and then saw this. It’s not dripping out but seems that it’s throwing some oil while the drive shaft rotates. Should I be worried? If so what fix am I looking at? Tried searching but having a hard time finding anything. Thanks!

 

Just a pinion seal leak. Not hard to fix.

You can drive like that forever as long as you keep topping up your gear oil. If you run dry, its a new rear end though.

Grease your U-joints while your at it. They look a little dry.

 

Awesome, I appreciate the info!

 

Two other things to check now that I think about it more.

The breath cap on top of the diff is notorious for getting plugged, this can cause your diff to get over pressurized and leak. Take that off and clean it out.

Also, in the picture it looks like there is oil coming out from the U-joint itself, usually a leaking pinion will cause a leak closer to the diff, right under the seal flange.

Its possible your pinion flange nut has come loose and its leaking internally around the threads, but that would be a strange failure.

In either cause, you do the same thing as you would for fixing a pinion seal but its something to check.

 

i used the original diff breather for when I relocated it. I will check and make sure it is still functioning properly.

I will also check pinion flange but as well as the pinion seal. Luckily, it sounds like it isn’t something to urgent as long as oil levels are good. Also, seems like a simple fox when the time comes.

thanks my guy!

 

Shouldn't it be dripping from the actual flange?



Also, if a flange leak shouldn't there be a splatter line across the bottom of the bed as the flange spins faster? Shouldn't it be flung further and further out?



I've never had this leak so it could be a pinion seal. Just seems really weird. Is the side of the flange facing the pinion wet? Or is it only we between the mating surfaces?

 

This is just what my fuel tank looked like when it started leaking due to rust under the straps. I opine that the pinion seal would be leaking from the other side of the flange, throwing lube in a much bigger arc, and the unmistakable fragrance of gear lube would be pervasive.

 

OP says he smelled gear oil. I agree though, the placement of the drip looks a little odd, but if its gear oil there really isn't anywhere else it could come from.

 

I had originally thought my fuel tank was leaking but it didn’t smell like gas, instead it smelt like gear oil. After wiping the fuel tank clean you can see oil bending flung on it. This is clearly the culprit:

 

Saw your handle and went to the fridge to get me an ice cold 805

The only thing holding the oil from leaking out is the pinion seal. As others have stated a pinion seal usually leaks out of the 3rd member. My theory is that the pinion seal is leaking at the inner portion of the seal where the pinion goes through, and travels along the pinion to reach the flange, rather than the outer section where the seal mates to the 3rd member. Either way... replace the seal and drink a beer

 

Indeed. So pinion seal it is. Easy fix

 

Haha @Cruzer glad I could inspire you!

Ya everything I have seen is it leaks out of the 3rd member but your theory makes complete sense. Might drink a few beers

 

You'll need a 30mm socket and something to unstake that staked nut. I used a chisel type bit that I thinned down to get in there. You should get a new nut for that as well.

Disclaimer I did the pinion seal on my 95 Tacoma and this is how I did it. I believe the tundras are the same.