I have an '86 Jeep Comanche with a leaking pinion seal, I don't remember how long it has been leaking. I thought it was the rear differential gasket and changed that but it still leaks. Hope I can go a little longer. It's been halfway across country once then all the way. It needs a new rear end but it is still holding up. I don't want it to break down on me. To much work to do. Please help.

  • What else seems wrong with the rear end? Why does it need a new one?
    – dlu
    Commented Jul 23, 2016 at 20:14

1 Answer 1


I assume you mean damage to the differential, not to the environment :-)

If the leak is slow and you keep up with it, you can probably go a long, long time before it is anything more than a nuisance. Slow means that between checks and topping up the oil the oil doesn't drop too low.

I've you've been running it dry, their may be damage already, but heavy gear oils won't drain away quickly and there should be a fair amount of oil below the pinion seal. You are probably OK, at least on this problem.

  • Agreed. To @LisaBelyew ... If you keep up with the gear oil, there shouldn't be an issue. Just keep an eye on how much it's leaking and keep it up to full. Gear oil is really slow to leak out, mainly because it's so thick. It also sticks to the gears really well. As long as the rear doesn't overheat, you should be golden. As long as the is gear oil is full (or near full) in the differential, you shouldn't overheat. Commented Jul 23, 2016 at 20:33
  • Thanks. I change the fluid every 3-5 mos when it starts sounding loke viscocity is going. So as long as the fluid level stays ok tjen i dont need to worry too much? And it is a slooooow leak. See a drop on the diffetential every now n then.thanks. Commented Jul 23, 2016 at 20:34
  • You're probably fine, but if you can hear a difference, I'd say you waited a little too long (maybe not in terms of prolonging the life of an already dying rear end, but if it was in good shape and you were hoping to keep it that way) the change of sound isn't a good thing – except perhaps that it reminds you to check :-)
    – dlu
    Commented Jul 23, 2016 at 20:37

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