06 Tacoma - Rear Differential Breather

[Nardog]

I changed the rear differential fluid on my 06 Tacoma 2WD today at 25,000 miles to avoid problems with axle seals.
While removing the top plug (fill opening) I noticed air venting out.
The air venting was audible and lasted for about 15 seconds.
My question is; isn't the breather supposed to equalize pressure to the atmosphere? I'm concerned that a positive pressure, that would result when the fluid is heated up, could force gear oil past the axle seals and cause a leak. Has anyone else experienced this? I plan on removing the breather and cleaning it with solvent and blowing it out with compressed air on my next day off. I should have done this today, but didn't think of it until later.

[Brian R.]

I think you're on the right track. There should be no pressure.

Be thankful you didn't remove the drain plug first and have a jet of gear oil all over your garage floor....

[hoofarted]

I did that same proceedure on my 95 Tacoma 4x4 a few years ago and had the same thing happen. What I found was when I removed the vent to check it, there is actually a spring and disc inside it to act as a check valve. With this setup air would be able to ecsape but nothing would be able to enter such as water when the rear axle is submerged. This spring and disc was clogged with goonk and wasn't allowing anything to pass in either direction. You could just leave the spring and disc out and the vent would work fine, but seems to me like Toyota had a pretty good idea so I cleaned it and reinstalled it and check it periodically (once a year).

Before finding this clogged vent my pinion seal was leaking. Not a lot but the housing was damp and I would see a drop in the driveway once in a while. After clearing the vent I pressure washed the housing and it never leaked again. I guess that pressure inside was forcing the fluid through the pinion seal. Weird thing is when I pulled that drain plug and air was blowing out, it wasn't a warm day, in the 40s and the truck was sitting overnight. Strange how pressure could be built up in there while the diff was so cool.

This was my first post, hope it helps.

[clicker01]

very helpful