100 series rear differential breather

[Faab]

I found out today from my mechanic that he forgot to change the breather.

The diff breather wasn’t installed by the mechanic as I had instructed, even though he told me he did on the new rear differential I gave him to install. The old one was dry on fluid when we went to change it, instead of re-gearing, and maybe the diff breather was the issue. Now I’ve driven about 1000 kilometers, and it’s leaking everywhere—around the center of the pumpkin and the right-hand seal, possibly also the left-hand seal near the wheels. I’ve stopped driving it.

4-Lo doesn’t work, and the center lock doesn’t work.

The mechanic admits he forgot to put the breather on and says he will handle everything and take care of it.

But what damage could have been done? What if it was the old breather not being changed that caused the issue with the old rear diff that the previous owner didn’t change and I only discovered weeks after buying it?

I’m worried that my new rear differential from Toyota may have been messed up by this mistake from the mechanic. What should be checked? Should the center gasket for the diff pumpkin be redone with proper RTV and a new gasket?

Also, how can I get the center lock and 4-Lo to work again? They stopped working right around the time the rear differential started leaking.

 

[SteveH]

Since you seem to be leaking everywhere, I would pull the diff fill plug and see if the diff is overfilled. Don't tear is apart until you do this. You could also drain the diff and be sure that it has roughly the right amount of oil in it. If so, then likely no damage was done.

If you paid a mechanic to replace the diff, he shouldn't have screwed this up, but if he did, you might want to take over yourself on checking the fluid level. Your diff breather hose looks original and crusty - be sure it isn't cracked near the diff connection point.

Your lack of 4Lo and center diff lock should be totally unrelated.

 

[excessive]

it's pretty easy to remove the breather tube + assembly. I'd remove it, and blow air through it and see if its blocked, it probably is.
Then check/ change the rear diff fluid as a precaution

 

[Bisho]

You can free up the breather by running brake cleaner through it. You may need to replace the hose if it’s brittle.

It almost looks like that oil is coming from the input shaft seal. If your breather is blocked it could blow out the input shaft or axle seals. Other than replacing the seals, it shouldn’t damage anything internally.

 

[Kofoed]

Regarding breather, I removed mine and run new hose up near the gas filler neck and placed a small engine fuel filter on the end to keep out dust. Axle seal leak disappeared. It was due to running hard after a super cold weather start.