I am going 4 wheelin with a few of the uk crew and it has been dropping a bit of rain down and i thought it would be a good idea to do the diff breather mod.
so there i am under my truck with a spanner in hand and i whip the breather off, on closer inspection i find it has a little cover on it, strange i thought must be there to keep the crap out, so i prise it off with a screwdriver and inside the cap is a spring and a rubber disc, it seems to work as a oneway valve ,so now i am a little stumped, is this normal and if so why bother with extending it as it cant suck water in? if it is not normal then what are your thoughts on it should i change it for a breather tube and filter also where is the front one located?

 

You need to extend it because if a hot differential gets submergen in cold water, IE. water crossing, then the diff rapidly cools and trys to draw in air. Since there is a one-way valve it can be pulled in through the seals. Since the diff is under water=, water not air can be drawn in .

 

i can see that but the valve will only let air out and not in? ahh now i get it i will get on to it first thing tomorrow, do i have to do it to the front one and if i do where is it located

 

While it's supposed to act as a one way valve, more or less, it's not actually all that good at keeping air from coming back in. Small pieces of grit get in there and keep it open, or it can let water in as it *burps*. Worst of all, as the spring relaxes, it won't close all the way.

If you plug it up, the pressure in the diff will cause leaky seals, if you don't, you risk water/crud getting in. The only real solution is to move the breather up out of harms way.

There's another write up (possibly Tacoma specific) on the WATTORA.COM site.