help with front diff waterproofing

[BCJC]

hi, i've had to replace my front diff fluid 4 times in 4 yrs., due to contamination. i live in the North West, so it's quite wet out here, and subsequently i drive through alot of puddles and streams. my fluid level never changes, so no leaks, all i can think of is my breather hose is leaking. any links or tips on how to do a fairly comprehensive "re-do" of my breather hose? appreciate any help.

jackson

 

[BigAl]

I wish i had some pics for you. What i did was tap my vent hole to I think 1/4 npt and screwed in a air hose nipple with teflon tape. I use a cheap spiral air hose (slinky style) which just snaps onto the nipple. I secure the other end to the top of the radiator. The spiral air hose allows my suspension to flex way down without tensioning the hose. Half the people who see it think its some kind of air locker.

 

[ntsqd]

Best concept that I've heard of is to very slightly pressurize the diff with air. Slightly, like 2-3 psi is what was mentioned. How to do that has been my question.

 

[Rexsname]

I have heard of this pressurization (sp) as well.........The way I heard it described was to "T" into the PCV valve and allow that small pulse of air into the front diff. No idea how well or if this would work tho..............

REX

 

[ntsqd]

I've heard of guys plumbing the vent(s) that way, but on that side of the crankcase ventilation system it is vacuum. I think that's counter productive.
On MISF's Scout I made a tube manifold that combines all of the vents (axles, t/c, trans, engine) into one hose going inside the engine's air filter. So it's still at atmospheric pressure, but at least it is filtered air.

Assuming one had OBA and could find a regulator that was reliable at that low pressure setting you could use that for the pressurized air source. I'm not sure if such a regulator exists. I've not looked into it.

 

[Fantom]

In my particular case the breathers used 1/4 hose, so I grabbed a spool of fuel line, attached to the existing breather outs on the diff, zap strapped to the break line and followed as many solid things as I could. Both the front and the back join under the hood to a small breather cap.
Have you noticed where the contamination is the greatest, does it get into your hubs as well or just the oil?
I had a look at different posts and specs on drilling new fittings into the case but decided to scrap that idea and give this a shot, in the end it cost me less the $30 to do both diffs and that's including a small fuel filter on the line to keep dust out. That said I don't know what type of breathers you currently have and if you can attach a hose to the diff. I have not had any issues so far and I've tried some interesting crossings.

 

[BCJC]

thanks to everyone. i'm still looking into the proper fix for this problem, so more info is welcome. cheers!

 

[madizell]

Just my opinion, but having operated off-road in Alaska for years, in deep water and deep bogs, I have never had a diff contaminated by water. I have, however, always had the axles vented through rubber line to a point as high on the vehicle as practical. The front diff is vented to a point just under the hood at the firewall, and the back diff is vented to the top of the roll cage outside my half-cab. No leakage.

I would not recommend pressurizing the axle housing. You invite leaks. I once had mud plug the body in the area where I used to vent the rear axle to, behind the taillight. The lack of venting caused a rise in pressure in the housing due to heat. Everytime I ran down the road, heat would build up and the axle seals would leak fluid. Once I removed the mud build up around teh vent, it stopped doing this. After that I moved the vent up to the 7 foot level to avoid all mud and water. No further issues.

Point is that the housings should be vented, not presurrized, and if properly sealed, won't leak water into the housing if the vent is terminated above the water line for your intended water crossing. Axles are generally very well sealed and would not leak water in unless they are also leaking fluid out. If yours don't leak fluid, any water contamination is coming from the vent. Raise the vent height and it won't be contaminated by water.

The 1/4 npt tap is a good way to go. Or, drill and braze in a short steel nipple such as brake line or other tubing of suitable strength, then clamp on a rubber line. I use rubber fuel line, as it is quite durable stuff.

GMc.

 

[BCJC]

very helpful, much thanks!

 

[ntsqd]

Note that in suggesting the possibility of pressurizing the axles that I intentionally suggested a very low pressure. Lip seals, by design, work better one way than the other. the way that they are installed is intended to keep stuff in more than to keep stuff out. Normal operation has a greater pressure (slight) on the inside of the housings. Reverse the pressure bias and the seals do not work as well.

I did fail to say that I would not run them this way all of the time. Only for deep or rapid crossings. The very valid venting issue you mention is from the lube's volumetric change due to temperature. That had better not be an issue in water crossings or you've got big problems.

Just my opinion, but having operated off-road in Alaska for years, in deep water and deep bogs, I have never had a diff contaminated by water. I have, however, always had the axles vented through rubber line to a point as high on the vehicle as practical. The front diff is vented to a point just under the hood at the firewall, and the back diff is vented to the top of the roll cage outside my half-cab. No leakage.

I would not recommend pressurizing the axle housing. You invite leaks. I once had mud plug the body in the area where I used to vent the rear axle to, behind the taillight. The lack of venting caused a rise in pressure in the housing due to heat. Everytime I ran down the road, heat would build up and the axle seals would leak fluid. Once I removed the mud build up around teh vent, it stopped doing this. After that I moved the vent up to the 7 foot level to avoid all mud and water. No further issues.

Point is that the housings should be vented, not presurrized, and if properly sealed, won't leak water into the housing if the vent is terminated above the water line for your intended water crossing. Axles are generally very well sealed and would not leak water in unless they are also leaking fluid out. If yours don't leak fluid, any water contamination is coming from the vent. Raise the vent height and it won't be contaminated by water.

The 1/4 npt tap is a good way to go. Or, drill and braze in a short steel nipple such as brake line or other tubing of suitable strength, then clamp on a rubber line. I use rubber fuel line, as it is quite durable stuff.

GMc.

 

[madizell]

Normal operation has a greater pressure (slight) on the inside of the housings.

Not when adequately vented. That would be the purpose of having a vent, to eliminate any pressurization, positive or negative. Internal pressure should be atmospheric.

 

[ntsqd]

Not when adequately vented. That would be the purpose of having a vent, to eliminate any pressurization, positive or negative. Internal pressure should be atmospheric.

That would be nice, but is unrealistic. Every single feature in the vent system poses a flow restriction. All of them combined is very likely not very much, which is why the "(slight)" wording, but any restriction will alter the internal pressure from atmospheric due to the thermal expansion or contraction of the lubricating fluid. Eventually the internal & external pressures will equalize if nothing further upsets the system balance. By that time the damage could be done, water could have found a path inside.

Please note the concept of a SLIGHT pressurization of the axles was a suggestion for consideration. Not a recommendation. I gather you don't think it necessary and that's fine. I'm not convinced that it would be a bad idea.