Hello - truck is an 01 tacoma 4x4, about 80k miles. Late last year, I had the diff and transfer case gear oil changed by a toyota mechanic. About a month thereafter, the pinion seal on the front diff began leaking, so I had it replaced. Two weeks later, gear oil blew out the breather tube, all over everything. Mechanic cleared out tube with air and added an extension, figuring maybe I got some crud in it. So here we are about a month from that point, and the left axle seal is leaking.

Any ideas what might be happening here? They're replacing the seal ($150) and removing/refilling the gear oil, but they have no clue as to why this might be happening.

I do some light off-road, but this being the desert, I can't recall ever driving in water any higher than 2 inches. plus I'm usually pretty good about power-washing any mud from underneath.

 

Sounds like a clogged breather. But you say its been blow up.

Did he check the fittings and make sure there is not clogged? Maybe a really tight kink? Usually as pressure builds the breathers will allow for the discharge of this pressure. If they become clogged it will blow seals.

Only thing I can think off.

 

I would replace the entire diff breather hose and verify with compressed air that the check valve works. Then use compressed air (in the inlet where the diff breather hose attaches to the diff with the fill plug taken out of the diff to allow the compressed air to escape) to blow out any crap that might be stuck, and then change the oil. This should verify that you can't get any overpressure buildup in the diff (which is usually the cause of leaking seals). I also wonder if they guy overfilled it the first time, it should not be filled past the bottom of the fill plug threads (ensure the truck is sitting level when doing this).

 

since you've cleared the hose, but still having issues, my guess is a bad check valve. you (your mechanic) most likely just put the old one back on after clearing the hose.

if you replace the front hose, go ahead and pick up a PCV breather/filter at napa/autozone, etc, and put it on top and junk the check valve. that way it will never get stuck and cause any more issues.

 

Don't know much about the check valve for the breather, but is it possible to install it backwards?

 

Nope.

I would bet Andy is probably right, but I would go through what I mentioned to verify there is no way overpressure can occur.

 

is it the same gear oil? as in visc. brand, syn or reg.?

 

yes, it's just basic dino, the same as the gear oil that had been in there for the last 30k. As for other comments - I think maybe you're right about the check valve. One idea I had was to take off the fill plug and shoot compressed air into the diff to see if it comes out the breather tube (which ends up against the inside of the fender). I'll see what happens this weekend. Meanwhile, I have now had the most expensive gear oil change ever!!

 

I don't believe it was overfilled -- though I couldn't actually check it, as the fill plug is hard to reach myself without the truck up on some sort of lift. The mechanic, who I've used for a long time and trust, says it would be nigh impossible, as the lifts aren't at any sort of angle.

Thanks for all of your input. We'll see what happens. At least 2 out of 3 seals are now warranted for a year!