rkymtnflyfisher
Trout Bum
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- #1,981
I wouldn't think that the oil would expand enough to leak, but I wouldn't rule anything out at this point.
Builds An Accidental Frame Off.................. (8 Viewers)
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I think it is unlikely that the oil in the diff housing and axle could expand to the extent that it pushes out the breather sitting on top of the axle. If that were the case then an extended breather would solve the problem if it allowed enough additional space for expansion - or if you provided an expansion chamber a la the radiator over flow.
What it could be is a combination of foaming of the oil, which foam does take up a lot of extra space and creates 'pressure" sufficient to drive it up and out in the form of oil-foam which then reverts to oil.
But, that would not explain the Land Roveresque spontaneous and gratuitous "burping" of oil which in any situation other than a Land Rover would require a build up of pressure which is later released. Maybe it could be a combination of the theoretical foam build up pressure left over from a previous drive and a "sticky" vent valve which then later for whatever reason unsticks itself and burps out some oil/foam.
Maybe some new gear oil with good anti-foam properties could help. Maybe a thorough cleaning of any gummy oil residue in the breather is what's needed.
Maybe I'm just bored out of my bracket and looking for some Land Cruiser work to do. Anybody near Beaverton OR looking for a free labourer.
What it could be is a combination of foaming of the oil, which foam does take up a lot of extra space and creates 'pressure" sufficient to drive it up and out in the form of oil-foam which then reverts to oil.
But, that would not explain the Land Roveresque spontaneous and gratuitous "burping" of oil which in any situation other than a Land Rover would require a build up of pressure which is later released. Maybe it could be a combination of the theoretical foam build up pressure left over from a previous drive and a "sticky" vent valve which then later for whatever reason unsticks itself and burps out some oil/foam.
Maybe some new gear oil with good anti-foam properties could help. Maybe a thorough cleaning of any gummy oil residue in the breather is what's needed.
Maybe I'm just bored out of my bracket and looking for some Land Cruiser work to do. Anybody near Beaverton OR looking for a free labourer.
Me three... and I also extended it and that eliminated the issue.
No idea why it does this.
My only theory is that gear oil is super viscous, so if it splashed off the axle onto the (small) breather hole, it may wick into the breather, then heat expansion of the AIR in the breather under use may push it out at some point later.
There shouldn’t be enough gear oil in the dif to be splashing out of the breather if I had to wager a guess it’s only riding up the axles up the tube and maybe sloshing in a turn or an off-camber situation. I’m guessing it might get deposited into the breather in those situations then pushed out when the axle “breathes” through the breather.
There shouldn’t be enough gear oil in the dif to be splashing out of the breather if I had to wager a guess it’s only riding up the axles up the tube and maybe sloshing in a turn or an off-camber situation. I’m guessing it might get deposited into the breather in those situations then pushed out when the axle “breathes” through the breather.
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rkymtnflyfisher
Trout Bum
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- #1,985
100 pages... dang boss. Here's to 100 more! 
We're gonna' have to connect one day with the other 40's running around western Montana.
We're gonna' have to connect one day with the other 40's running around western Montana.
rkymtnflyfisher
Trout Bum
- Thread starter
- #1,987
100 pages... dang boss. Here's to 100 more!
We're gonna' have to connect one day with the other 40's running around western Montana.
100 pages of shenanigans that could be distilled to 5 pages of tech info.
There are a few 40's in this area, maybe 12 in the valley that I see often. I'm sure there are many more.
Cheers!
What about deleting the breather cap all together? I am a certified idiot but what would really happen?
The axle assembly would still vent - most likely through the seals and gaskets.
At how much pressure? I guess it makes me wonder if the breather is designed at too low of a vent pressure.
rkymtnflyfisher
Trout Bum
- Thread starter
- #1,992
No pressure at all, just a vent.
Exactly, on my oldie the vents are basically nipples with a cap loosely crimped on.
FWIW, I'm 'remote-ing' mine to hopefully keep any water from getting in.
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I guess I still don't understand the physics of why it can't just be deleted.
You may certainly delete them.
Just be prepared to clean up the mess when the lube, which expands and contracts as does the atmospheric pressure, is forced out.
Most every machine that contains liquid lubricant will have a vent to avoid either pressurizing the inside causing leaks or allowing
outside contaminants to be drawn in due to a slight vacuum forming.
As @flee said above, it can also draw stuff inside through the seals where there to be a rapid cooling. So if you say were fording a small creek and there was rapid cooling, the vacuum could pull water into your axle, which is no bueno.
This and what OregonFj40 said makes a lot of sense. Thanks for clarifying.
Local LC shop has been using these. You can get them at Summit
FJBen
SILVER Star
Clogged vents are no good anywhere. A clogged vent blew out some seals in my split case. Living on a dirt/muddy road locked that tcase breath up. When I went to find out why the front input started leaking back, I found that OEM breather was all crusty/packed with dirt and wouldn't move. I've since rebuilt tcase and ran extended hose into the engine bay.
If I am not mistaken the breather has a spring and a ball in it to hold it closed. It pushes out and then burp then reseals. That is why you do not get water in during fording water. It may have an o-ring in there as well. It has been a while since I took one apart.
Those vents posted above blow up like ballons when you run them down the highway. Guys at KOH run them but you need to cut a small slice in it to allow it to burp.
Those vents posted above blow up like ballons when you run them down the highway. Guys at KOH run them but you need to cut a small slice in it to allow it to burp.
