Cases for or against extending transmission and trans-case breathers

[Hillbilly Heaven]

Extending the vents is an excellent idea. I would use separate rather than combining them all especially if you have an automatic transmission. If transmission overheats there is a possibility of it puking. If it does then you have cross contaminated the axles. Granted mixed lubes is least of your worries at this point.

One item most don't think of is water ingress into engine and mounted accessories. Dip sticks should have some form of seal. Most modern day crankcase vents are routed to the intake air so that should be already taken care of.

Now here is the one most don't think about is power steering pump. It is vented and usually one of the lowest mounted accessories. You can't seal it as it does build pressure in the reservoir. If your system has a remote reservoir then it is already mounted high from factory and vented.

 

[Hillbilly Heaven]

Might want to consider some form of these. I like the closed expanding bellows for axles and transfer cases. I am using their power steering vent with anti-splash and pressure relief for my steering system.
http://www.pscmotorsports.com/motorsport-specific-products/offroad/reservoirs-overflow-bottles/vent-kits

 

[rayra]

Just a note on 4wd GMT800 Suburbans, they're already equipped with breather tubes extending to about the height of the factory tires, ~32". The rear axle is routed up into the void behind the left rear tail light. The transfer case and trans up to the rear of the engine block on plane with the intake manifold, about where the oil pressure sender is. The front axle vent tube is on the driver side front wheel tub roughly between the shock tower and the master cylinder. So as long as your fording doesn't exceed your (factory) tire height, you're already good.