OK, has anyone experimented with pressurizing the differentials transfer case tranny and other things to inhibit water intrusion? I've only been able to find small amounts of information on the subject.

I would think it would be easy enough to run a cheapo air compressor and pressure switch of some kind. One guy (who hadn't actually done it) was concerned that gear oil would puddle in the line (like from the rear diff) if it didn't slope all the way back to the axle and make for a no breathe situation.

What PSI? I assume 1-3PSI

Are there pressure switches or pop off switches of some kind that are for really low PSI?

Could you run one common line for everything?

Do you really have to worry about gear oil coming up the breather hose that far?

 

that is a very interesting/cool concept but are you really having that serious waterproofing problems?

 

That wont work. Most likely you will blow out your axle seals or blow oil around them. The only time you will really experience oil in a vent tube is if you roll over. All you need to do is route the vent/breather lines to a common point where you know there will be no water. A lot of people route them to the air box. If you have a flooded air box the chance is great you will have bigger problems than water in your gear oil. If you have water getting past the seals then the seals are shot.

Matt

 

Yeah, bad idea, diffs and transfer cases and transmissions are vented for a reason. Usually if you plug the vent, it wont be long before you blow a seal out, which is basically what you'll be doing.

 

you'd be surprised how hot it gets inside a diff. ever grab a piece of metal after grinding on it? cant hold it for long with bare hands! bout the same thing!

-cutts-

 

let me clarify, I don't mean hooking it up to the shop compressor and using it as an air tank at 120 PSI, I'm simply talking about taking the existing vent lines and having a valve you could close then apply SMALL amounts of pressure only when you are in a deep water crossing or something.

How come some military vehicles have it? I think unimogs used exhaust pressure didn't they?

I haven't had problems yet but I've avoided cirtain places because of it, basically I'm just interested in the concept for preventative kind of action. since I am planning on routing all the lines to the same spot anyway i'd like to figure out if it'd be worth it.

Anyone who knows what they are talking about or has actually dealt with this type of thing?

 

yea... the last time my front vent line got clogged i blew both inner seals! most axles are not meant to be put under pressure (whether .5 psi or 200 psi), hence the reason for a vent!

are you trying to re-invent the wheel here? i find it'd be much easier to just run a vent line up under the hood and add a small filter of some sort!

but hey, call me weird

-cutts-

 

Do you work in an area where combustable gas is present, and this principle is used to keep combustable gas out of control cabinets?
Interesting that you bring it up. I am amazed at how in depth some people think. Very good idea.
Now, I will tell you why it does not work. You want to introduce positive pressure into a t-case, or differential, and these alone already create positive pressure when they geat up, that is why the vent is there. You will vary this pressure with every few degrees of temp change. Keeping equal pressure inside the diff and atmosphere is critical to keeping the fluid inside. Too much positive pressure and the oil is pushed out past the seal. Too low (vacuum) and there is a potential for stuff to get sucked in. (highly unlikely)
All of which is difficult to do since the vent is open to atmosphere, this keeps the pressure outside equal to the inside.
Alright, now you intend to increase inside pressure to the outside pressure, as the outside pressure is increased due to water submersion. Well, this in itself is a great idea, but becomes very complex, since you would have to be able to establish what the new presssure is and then run compressed air into the t-case or axle without over pressurizing it, (oil will leak out) while taking into account that the axle is hot, and trying to create its own pressure already. Provided the vent works and is not plugged you would need a regulated amount of air with enough volume to occupy the space of the t-case, or axle and maintain the proper internal and external pressures. Then and only then would this be possible. This means that data has to be monitored in real time and a device has to control the pressure, volume, and compressor to keep a balance of pressure. Not to mention that you would need a compressor capable of running when the vehicle runs.
Will your theory work, yes. (limited, still would not be 100%)
Does it require more than just sticking some pressure in it? Again yes.
Worth the effort and expense? (for cool points, yes), but for being practical, no.

Keep the vents high and free flowing, and you will be pretty safe. As a regular part of preventative maintenance, you should be inspecting the fluid anyway.
Fresh new seals will probably do a decent job.

Good creative thinking.

 

thanks for the replies, sounds like I don't need to worry about it.

Does anyone know about the unimog exhaust pressure thing? I'm still curious

 

Here's the thing; if you only applied the pressure when you needed it, it wouldn't blow axle seals.

If you only engaged the pressure as you were about to do a water crossing and had just enough pressure to overcome the water pressure you wouldn't blow seals and you would be guaranteed to not get water in your system.

If you wanted to run pressure all the time i'm sure you could do it, but it would probably invovle some fancy seal retainers and some extra o-rings.

Justin

 

that's more what I was thinking, having it vent regularly unless I encounterd water, who knows I might experiment with this somethime. Thanks

 

After reading both of your post...(waterproofing a NP435 and this one) Im inclined to believe that unless you are planning to ford (ford the verb not ford the noun...well maybe ford the verb with ford the noun) the mississippi river you will never be in enough water to stop a NP435. Im with fishy, I know my vent tube is clogged when my rear axle seals leak. I cant say Ive ever had any trouble with water in the NP435 in my 79 F150 4x4 but its a trailer queen that would melt in mud or water. Id just do what I do which is change the fluid in the engine tranny xcase and diffs pretty regularly. I dont play in deep mud that often but Ive found that every 3 times seems to be a reasonable changing point. For me thats every 4-5 months. Im not counting playing in mud I talking DEEP water saturated mud.