What -IS- a differential breather? Every differential has a breather. It is usually just a vent to the outside air, covered by a cap that helps keep debris out. It is there to equalize the pressure in the axle as the temperature within the axle changes. Without a breather, or if your breather is clogged, the pressure that builds up inside the axle housing will most likely push gear oil past your pinion or axle seals.

Why would you want to modify the breather? The stock breathers have no way of keeping water out of your differential case if you submerge the axle. (i.e. stream crossing, ocean, etc.) The problem is, when you submerge the axle (for more than a few seconds) the temperature inside the axle goes down and the pressure inside the axle also goes down. This pulls whatever is on the other end of your diff. breather into the axle housing. If you're axle is under water, it will be pulling in water. If you've pulled in water, you need to chage the gear oil soon, or down the road you'll most likely be looking at some damage.

I don't like changing my gear oil all the time, are there other options? Why yes! Funny you should ask. You can install extended breathers. The idea is to get the point where the breather draws in air, as high as possible. To do this we use hose (I used vacuum hose), and run the hose up into the engine compartment, or other convenient location.

Thanks to info posted to the Toy4x4 E-mail List I learned of a Nissan breather that fits perfectly into the threads that our stock Toyota breathers use. The Nissan part number is 38323-C6010, and I was charged $4.50/each. The difference between this breather and the Toyota breather, is that instead of having a cap to keep debris out, it just has a long stem, perfect for attaching a hose to. The picture on the left is what the nissan part looks like sitting in the top of the differential housing.

The picture on the right is the yellow fuel filters I have at the top of my breather lines, in the engine compartment. The filters are not absolutely necessary...it's up to you if you put them there. (Please do NOT e-mail me and ask me what filters I'm using...they were just something I found in a parts store....I have since removed them, and am not using filters.) If I remember correctly the hose I used is 7/32" vacuum hose, availible at most auto parts stores.

Here is a picture of the finished (and dirty) product. I used two black hoses, with yellow fuel filters on top. (to helps keep dirt out) You can see part of the breather, the hose that is attached to it, and the small hose clamp I used to keep the hose on there. On the front differential I had to cut the Nissan part just a little bit so that there would be a bit more room between it and the oil pan. Installing these is a piece of cake. If you use the banana scale, this is a 1 banana job. :-)

These breathers perform at least as well as breathers that sell in magazines for well over $50

UPDATE: Thanks to Erik Romero, I now know the Nissan part fits perfectly into the Tacoma axles as well. Thanks Erik!
 

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