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
12/4/2000
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. In general you want the hose as short as necessary with no drooping sections for oil to pool in and clog the system. If water gets to the fuel door I'd probably be wet to the knees. Zip tie the hose securely.
If you have an ARB locker up front and you are experiencing heightened breather issues such as oil coming out the breather, here is another possible solution. Due to the fact that the stock breather is very small, very low on the diff housing near the oil and has many bends in the line, it takes only a small amount of internal pressure blow oil out of the breather. One solution is to lower the fluid level about 1/2". If that doesn't work you can try adding a second breather. Here's a tip from Daniel Bongard at ARB.
Take a rear axle fill plug and drill through it with a 3/8" bit. Then tap the hole
with 1/4" NPT (which is about 3/8").
Screw in a 3/8" barbed NPT fitting and then install it in the diff. Ideally some of
the housing should be ground away on the left side to provide more room to tighten down
the fittings. However the fill plug does not have to be very tight.
I installed some cheapy clear 3/8" hose so I could monitor how far the oil travels up
the tube. On the engine compartment end I installed a cheap fuel filter.