pinion seal leak - diff breather question

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Oct 28, 2007
1997 FZJ80 145k

My pinion seals have shown no sign of leakage at all. Yesterday after returning from a weekend trip I noticed diff fluid all over the rear of the truck. Seems like a rear pinion seal leak. Maybe it's something else? I had traveled through some farily deep water (Mojave River - Afton Canyon) just before heading home and I've read some info that a clogged breather can cause the fluid to push pass the seal when trying to equalize. I extended my breathers to the engine bay last year so I don't think they are clogged. Maybe I slightly overfilled the diff fluid if that could cause the seal leak?

The questions is: if it's the pinion seal, once the seal has been pushed past, do I need to assume that it's now compromised or is it possible that I can clean up the mess, replace the fluid that was lost, and keep driving on it?

Could it be anything other than the pinion seal?

I think I would just clean it up, and top off the fluid, then keep an eye on it and watch for any leaking. Also check your breather and make sure its not clogged, should be quick and easy since you relocated it. I've noticed leaks from my rear diff after wheeling as well, and no leaks while just daily driving. I think the wierd angles of the rear end while wheeling cause diff fluid to puddle up in areas not usually exposed to puddles of fluid, and thats when it leaks.
Yeah, I'll clean it up under there and watch for how much it's actually leaking under normal driving conditions.
Running the rear breather tube all the way to the engine compartment is troublesome from my personal experience. I used rubber fuel line and zip ties to get it up to the engine compartment and it was too restricted. I had oil push up my ARB hose to the actuator in the engine compartment. I shortened it by routing it up by the fuel tank hose and drilled a hole so the line terminated in the fender area where the jack is stored.

Like mentioned before, try clearing the hole with a small screw driver. I don't know where the crap comes from, but every time I change diff fluid, the hole seems to be partially block.
Hombre, do you have the factory valve on the elongated tube that clogs, or is the tube open at the tip and clogs?

As I was extending that breather tub all the way to the engine bay, I wondered if it would allow enough air exchange to be effective. I will check it to see if it's clogged or not. At the open end in the engine bay, the tube has a small cheapo fuel filter which allows easy air movement but is meant to trap dust. Maybe that's clogged with that fine desert dust that seems to get into everything.

So the main question remains - do these pinion seals get permanently compromised once the diff fluid had pushed past once?
I screwed in a nipple fitting into the diff housing and the crust seems to build up on the inside surface of the housing. I never see it but when I jam a small screwdriver in there, I can feel that I knock something out of the way. The end of the tube is a lawn mower plastic fuel filter.

I still get diff oil in the ARB tube. One time I had to cycle my rear air switch a few times to get my locker to ingage. I figured I had to move some oil down the tube and get some oil out of the locking collar area so air could get in there to lock the diff. Oil no longer migrates out of the air switch during normal driving.

The one time I had a pinion seal go bad, it started to weep and leaked out slowly. I paid a guy to fix it and he did it with everything staying on the car. It looks to be an easy job, and if I knew then what I know now, I would have done it myself. Sounds like yours puke it's guts out and I would wonder if a part of the lip somehow got pushed out and displaced the seal spring.
diff breather

The problem with the factory diff breathers is the check valve. The valve allows air to escape as it heats and expands, but does not allow air to enter as easily when cooled. When you drive into water and the axle is rapidly cooled the air contracts quickly and needs to pull from somewhere. If it cant pull easily through the vent tube, than it can pull water through the seals. Best thing is to run the vent tubes high enough that you wont submerge the end, you can then leave it open if its in a semi clean place , or even put a little filter on the end, like a pcv filter or something.

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