Toyota rear axle vent caps

[teotwaki]

When installing my ARB locker last Saturday I started with removing the drain fill plug and was surprised to hear some air "whoosh" out. I decided to check the vent cap which I had placed at the end of a rubber tube high up in the gas fill hatch. Originally the vent cap was mounted right to the axle.

The little cover freely moved and there were no obstructions. Close up

I pulled it off and checked it out and found that it seems to be a one-way pressure relief cap. If you try to suck air into it nothing happens. Blowing on it takes a little bit of pressure before air goes out.

I'm guessing that Toyota want to prevent the free ingress of moisture-laden air or water surrounding the axle. They seem to allow a slight amount of air pressure to build up within the axle to help keep water out. At some point enough pressure will overcome the limit of the vent cap and let air out.

The reason that I bring this up is that a number of folks have had an issue with the ARB Air Lockers letting diff oil somehow through the locker and go back up the air line and vent out of the solenoid on the compressor. There has been speculation that air pressure buildup in the axle is the culprit.

One solution is to remove my OEM pressure relief vent cap and replace it with a small paper filter which would prevent any pressure build up at all.

Big thread at the FJcrusierForums
http://www.fjcruiserforums.com/foru...-rear-differential-e-locker-breather-mod.html

Maybe not a good idea as the axle would be free to breath in moisture laden air?

Thoughts?

 

[4x4mike]

Excess pressure (like from a glogged vent or extension hose) will let gear oil seep past the inner axle seal. I've had to replace the seals on my 4runner twice. I've since purchased a new vent valve as well. Nice catch on being a potiential fix for the ARB's.

 

[teotwaki]

Excess pressure (like from a glogged vent or extension hose) will let gear oil seep past the inner axle seal. I've had to replace the seals on my 4runner twice. I've since purchased a new vent valve as well. Nice catch on being a potiential fix for the ARB's.

Thanks for the credit but others have thrown out the idea before. I just wanted to add my observations to the mix and see what sort of discussion ensued.

One thread: http://www.expeditionportal.com/forum/showthread.php?t=29114&highlight=ARB

another troubleshooting link: http://www.cruiseroutfitters.com/tech_ARB_troubleshoot.html

 

[keezer36]

You've seen the moisture seperator in 4307's thread?:

http://www.expeditionportal.com/forum/showthread.php?t=20110&page=14

http://www.longacreracing.com/catalog/item.asp?id=931&catid=19

 

[djrez4]

With the paper filter, you have to be sure to mount it somewhere that won't expose it to water during a stream-crossing. My front is in the engine bay and rear is up near the frame. Not the best solution, so, I'm planning on installing these. It allows for pressure changes within the diff, but is completely water-tight.

 

[teotwaki]

With the paper filter, you have to be sure to mount it somewhere that won't expose it to water during a stream-crossing. My front is in the engine bay and rear is up near the frame. Not the best solution, so, I'm planning on installing these. It allows for pressure changes within the diff, but is completely water-tight.

Right about the location. That was why I put mine up high by the gas tank filler tube.

Is that Creeper Breather sealed? Does it merely balloon/expand outward when the axle is hot then collapse again when the axle cools off?

 

[ntsqd]

A simple welding project

Years ago I made this from 2" muffler tube and some ~1/16" sheet stock. Use a hacksaw to cut the baffle slots, then insert a piece of the sheet into a slot, mark around the OD of the tube with a Sharpie, and cut the sheet to the outside of the Sharpie mark if TIG/GTAWing or Oxy-fuel welding, and just fuse the sheets in place using the excess sheet stock for filler. The top and bottom are more sheet stock cut and welded with the same method. I welded on hose nipples, but were I doing it again I'd use NPT bosses from McMaster-Carr.

My front & rear axles and the transfer case are plumbed to the bottom ports. On top I have a cheap crankcase/valve cover breather from Summit. It is currently mounted on the RF shock hoop inside the engine bay about as high as the hood will allow.

Good call on the potential issue with ARB's. I guess I get to make another one for the FJ60 project.

 

[daverami]

With the paper filter, you have to be sure to mount it somewhere that won't expose it to water during a stream-crossing. My front is in the engine bay and rear is up near the frame. Not the best solution, so, I'm planning on installing these. It allows for pressure changes within the diff, but is completely water-tight.

Has anyone used these for a time? I would be interested in these also.

 

[teotwaki]

You've seen the moisture seperator in 4307's thread?:

http://www.expeditionportal.com/forum/showthread.php?t=20110&page=14

http://www.longacreracing.com/catalog/item.asp?id=931&catid=19

The seperator is an interesting idea!

 

[dustboy]

This might be a dumb question, but has anyone ever shown proof that water can get in through the breather?

Here's my logic: Driving on dry road, axle heats up, air inside expands and breather allows some air out.

Now you cross a stream, axle cools off creating a vacuum inside the axle, because the breather is a one-way valve it should not let anything in. Likewise, the slight positive pressure as teotwaki mentioned, would help prevent leaks through the seals.

Makes sense that Toyota engineers would have thought of this.

 

[cruiseroutfit]

This might be a dumb question, but has anyone ever shown proof that water can get in through the breather?

Here's my logic: Driving on dry road, axle heats up, air inside expands and breather allows some air out.

Now you cross a stream, axle cools off creating a vacuum inside the axle, because the breather is a one-way valve it should not let anything in. Likewise, the slight positive pressure as teotwaki mentioned, would help prevent leaks through the seals.

Makes sense that Toyota engineers would have thought of this.

That is the way it theoretically should work but I can vouch for the fact water can get passed these vents with often disastrous results. They need to be cleaned and inspected every once in awhile to verify they are clear and the cap is moving freely.

 

[keezer36]

The seperator is an interesting idea!

One thing I wonder about the LP air moisture separator is (never having taken one apart) do they need XXpsi acting upon them?

Perhaps something with a desiccant that's changed out every six months.

 

[p1michaud]

Diff breathers

For my last rig and current rig, I've simply extended the diff breather up into the engine bay and used a simple $5 fuel filter at the end of the hose to prevent contaminants from entering the diff (think dust, dirt, mud, water etc...). Both rigs had ARB lockers installed. I've never seen evidence of moisture ingress due to air moisture when changing diff fluid.

Now the only way to properly understand the effect of moisture laden air entering the diff housing via the air breather through a simple paper filter would be to have the diff oil sampled for moisture content at regular intervals between change outs. The catch is that you would have to do it with the OEM toyota breather installed then again with a relocated/paper filter set up. Where you will have an issue is to replicate the exact same conditions with the two different set ups (environmental conditions - amount of moisture in the air, trails you drove, oil types, etc...). Nearly impossible outside of a lab.

My gut feel, you won't have an issue with moisture laden air entering your diff.

Cheers,
P

 

[CanuckMariner/Nomad]

... They need to be cleaned and inspected every once in awhile to verify they are clear and the cap is moving freely.

Maintenance is everything on a rig when one travels a lot solo and to remote locations.

As Kurt said, they need to be cleaned. I have all 4 breathers (diffs, trani/transfer case) going to my engine bay tied into one breather. This can be easily removed and cleaned with brake fluid, WD40, gas, etc. and reinstalled. The stock Toyota breathers work fine, no need to replace with any new devices.

 

[soonenough]

Has anyone used these for a time? I would be interested in these also.

I've been using one for close to 2 years w/ no issues as of yet. I'm pretty sure TejasYota's build thread on TTORA has some details about installing a creeper breather, so he's definitely been using one for a while. You might shoot him a PM and see how his is working (he's here on ExPo as well).

Here's my logic: Driving on dry road, axle heats up, air inside expands and breather allows some air out.

Now you cross a stream, axle cools off creating a vacuum inside the axle, because the breather is a one-way valve it should not let anything in. Likewise, the slight positive pressure as teotwaki mentioned, would help prevent leaks through the seals.

Makes sense that Toyota engineers would have thought of this.

This is one of the reasons I decided to use a creeper breather; I didn't want to ever create a vaccum inside the axle, because I think it creates the possibilty for the axle to suck air/water/dirt past the seals. The Toyota breather is simply a spring-loaded check valve (I saw pics somewhere online of the internals of one, and it's nothing more than a small spring with a seat that loads into the housing).