X2, I use air cooled VW fuel filters, their small, cheap and easily available.
True, but if mud gets to them I would have bigger issues, they are inside the rig.The weakest link is always your smallest orifice for clogging.......which on those VW filters is the ends.....very tiny-so much so that one little dollop of mud/grease dirt will clog it and prevent breathing. ...
Go to the "too much clam beach" thread. Look at what can happen when a hub rapidly cools and sucks in water.In an ideal world---a zerkable birf plus a balloooned axle would be the best solution.........fully sealed axle---and hubs/birf area that could be zerked/greased to pump out any water immediately after a fording---that way the axle is its own fully sealed environment--passively protected vs. relying on electrics and plumbing. Zerked birfs would allow you to top off before fording--and pretty much prevent water entrance. Still would need some sort of grease blowoff/blowout valve for highway speeds when the birf pressure increases and wants to force all that extra grease you put in pre fording-out (or thru your axle seals into the axle).
https://forum.ih8mud.com/80-series-tech/223544-diff-breather-manifold.html#post3356083The stock "breathers" are one way valves, in theory they allow air out, but not in. At first glance this looks good, in real life, not so much. As the gear box warms, the air in it expands, the excess goes out the breather, when it cools the breather closes and if the housing was totally sealed there would be a vacuum. In real life no gear boxes are totally sealed and air is drawn in through the seals, etc.
Seals are designed to work one way, in most cases to keep oil in the box. Outside pressure can easily drive air, water, etc past them. With the stock setup, water is most often pulled in by vacuum. The rig has been driven, the box is at temp and submerged, this rapidly cools the box and air in it, it contracts, causing a vacuum that pulls the water in through the seals, etc.
By going to a free flow system some of this shortcoming is eliminated, but the fact is that most any stock automotive gear box is going to get some water in it when submerged. Most of the time, with short submerging, it's in small amounts that will be evaporated out with normal heat/cool breathing. But say that your crossing and the motor floods, or you get stuck, etc, now the box is setting submerged until the issue can be corrected.
How many have you wheeled with that climb under the rig and remove the fill plugs to check for contamination after each water crossing or even at the end of the day? Why would you, I have a breather system, have crossed deeper water before, etc, the point is that most times you don't know that a box is flooded. So it's a highway trip home, then you notice the fluid on the ground or check the fluid level and find the box full of mayonnaise.
The most effective way of "sealing" gear boxes is pressurizing them with air during a crossing, for most it's not worth the hassle. If you have seen one working, it's a good way show how much they leak, bubbles everywhere.
Here is a picture of the same breather end from George's write found at:
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Does anyone know what part this tube vents ? ($64k question).
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