Extended rear breather install

If you ford water on any of your offroading excursions, you may want to consider raising the the axle breather on the rear end. The breather is a small valve that is mounted atop the axle and allows air pressure to escape the axle when it heats up. Without a way to vent, the axle will blow oil past the seals. The Toyota unit is a one way valve that allows pressure out but closes a valve to disallow things from getting into the axle. If the valve operates properly, the axle will have a slight vacuum when it is cold. There are several dangers to the stock system. One is that the valve is on the differential housing where, although it is fairly high, it can be swamped with water on a more serious stream crossing. Why test the valve if it can be avoided. Second, since it introduces a vacuum, it is possible to suck water past the axle seals and into the axle. How common this is I cannot say. I suspect that it is unlikely. Third, if the valve gets fouled with dust or dirt it may become disabled and allow water in. Both the front axle and the transmission/transfer case also have breathers. The front axle's is raised into the engine compartment by Toyota and the transmission's is high up where the shifter enters it.

I don't often ford deep water, but it only takes once to ruin the axle. A friend who has a Dodge Ram just had the pleasure of replacing his rear end from fording stream that lies in the way to his ranch. Regular crossings did it in. It was warning enough for me so I decided I'd raise the one low breather on the rear end.

The parts needed are pretty simple:

5' length of 3/8" fuel line
Two small hose clamps
Toyota P/N 90404-51319 or Nissan P/N 38323-C6010
Toyota P/N 90930-03136 or a small fuel filter
Zip ties

Tools needed:

13mm, 14mm wrenches
flat heat screwdriver
cutting tool for hose

Simply unscrew the old breather from the axle and screw the new fitting into the axle. Thread a clamp onto the hose and install it on the fitting. Route the hose to the underside of the vehicle and over the frame. Make sure to leave plenty of slack in the hose to allow for axle drop. Install the breather cap on the other end of the line and clamp it off. I ran the other end along the gas fill line to the backside of the fuel filler door. This was high enough for me. If water gets that high I'd probably be wet to the knees. Zip tie the hose securely.