Building My Overland Tacoma: Plans, Progress, Perplexions

[taco chaser]

Have you ever used or heard of a Woodsmans Pal?

Your truck build has come a long nicely by the way.

 

[Overland Hadley]

Have you ever used or heard of a Woodsmans Pal?

Your truck build has come a long nicely by the way.

Thanks!

Funny thing about that Woodsmans Pal, I was just looking at one in a magazine. I have never used one, but they look like quite the tool. (no "saw" blade/edge though)

 

[Overland Hadley]

I am lost in my brain...

A question about the rear diff breather extensions.

Does a diff breather really let the system breath, air in/air out, or does it just bleed the system when it gets hot?

I was reading a install guide on Toyota120, (Link) and the author mentions that the stock breather has a one way valve, allowing air to be blown out but, I am asuming, not sucked in. If this is true, then the breather would be more of a burp valve, and it would seem very hard to bring water into the system through a one way burp valve. I have not worked with my diff breather so I do not know if any of this is true, I also realize the article is for a 04 4Runner.

So are the rear diff breathers on 05+ Tacomas a one way valve system? Has anybody tried to push and pull air through theirs when they had it off for the extension? And if it is a one way valve, and if you plan to be under water for less than twenty seconds lets say, is a extension really needed?

I hate to work with things that do not need to be worked with. And the following post brings up some interesting thoughts.

From "To plumb or not to plumb"

One thing you have to kepp in mind when extending the vent hoses is the "Garden Hose Syndrome". The longer the hose for a given ID, the more restrictive it is to flow. I know we're talking about a vent, but I've seen issues with too small of a hose. This can cause a small vacuum in the axles.
A vacuum makes it easier for the diff oil to cavitate & form air bubbles entrapped in the oil. Air is not a very good lubricant. This seems like a really trivial thing, but I've seen it cause problems.


You don't want a vacuum in the axles if you are making water crossings. That will just make it easier for the water to gain entrance. If anything you want a couple psi (At MOST!) of positive pressure in the axles.

Thank you.

 

[ntsqd]

A one-way check valve could be a good thing on a breather mounted on the axle. It has the potential to stop water from being sucked in due to the sudden chilling of the axle on immersion in cold water, but it has the problem of holding the small vacuum I mentioned in the cross post. The small vacuum can be enough to allow water to weep past the lip seals in the axle. It isn't likely to be a lot of water per crossing, but if you don't catch that water got in.....

I think the better plan is a vent hose with no check valve routed up to above the maximum intended fording depth. Then the inside of the axle is always at ambient air pressure. On the vehicles that I have extended vents on I've used some form of filter at the end of the extension. One vehicle got a manifold with a K&N crankcase breather filter that all of the vents were plumbed to. Way overkill, but I had it laying around. Another got a vendor's kit with a much smaller manifold with a much smaller, but similar K&N filter. My 'glass buggy got one of the inexpensive plastic bodied inline fuel filters stuck in the end of one hose and a tiny K&N style filter on the other vent.

 

[Photog]

I plumbed mine up to the fuel door, and used one of the cintered-metal fuel filters in the end of the hose.

I also agree that ambient pressure is best, that way there is no vacuum or pressure on any seals in the axle housing.

 

[Overland Hadley]

I plumbed mine up to the fuel door, and used one of the cintered-metal fuel filters in the end of the hose.

I also agree that ambient pressure is best, that way there is no vacuum or pressure on any seals in the axle housing.

A one-way check valve could be a good thing on a breather mounted on the axle. It has the potential to stop water from being sucked in due to the sudden chilling of the axle on immersion in cold water, but it has the problem of holding the small vacuum I mentioned in the cross post. The small vacuum can be enough to allow water to weep past the lip seals in the axle. It isn't likely to be a lot of water per crossing, but if you don't catch that water got in.....

Thanks guys.

Thats what sounds right, I just had to much info running around in my head.

 

[Overland Hadley]

I have a hot water heater in my truck! Should be plenty of hot water for a few showers.




Although I am a bit worried about how much space it takes up.

 

[heeltoe989]

I have a hot water heater in my truck! Should be plenty of hot water for a few showers.




Although I am a bit worried about how much space it takes up.

AHAHAHAHAHAHA should do you just fine!

 

[soonenough]

...the stock breather has a one way valve, allowing air to be blown out but, I am asuming, not sucked in. If this is true, then the breather would be more of a burp valve, and it would seem very hard to bring water into the system through a one way burp valve....So are the rear diff breathers on 05+ Tacomas a one way valve system? Has anybody tried to push and pull air through theirs when they had it off for the extension? And if it is a one way valve, and if you plan to be under water for less than twenty seconds lets say, is a extension really needed?.

I was wondering about this exact same thing when I did mine. It seems like you'd be better off with the pressure in the diff open to the atmosphere, so that you don't have the tendency to create a vacuum and let liquid creep past the seals (as ntsqd mentioned).

Rather than going through the hassle of running the hose just to keep water out of the diff (not that it's really that difficult or anything), I ended up using a Creeper Breather on my truck. It's just a little bellows-type device that expands and contracts with the pressure inside the diff. It took less than 5 minutes to install, and although I haven't had any problems with it yet, I haven't had the axle submerged so I can't comment on it's underwater performance.

 

[slooowr6]

I was wondering about this exact same thing when I did mine. It seems like you'd be better off with the pressure in the diff open to the atmosphere, so that you don't have the tendency to create a vacuum and let liquid creep past the seals (as ntsqd mentioned).

Rather than going through the hassle of running the hose just to keep water out of the diff (not that it's really that difficult or anything), I ended up using a Creeper Breather on my truck. It's just a little bellows-type device that expands and contracts with the pressure inside the diff. It took less than 5 minutes to install, and although I haven't had any problems with it yet, I haven't had the axle submerged so I can't comment on it's underwater performance.

Neat idea! I wonder how much the bladder is going to expand if you drive the truck from sea level to 8000 feet?

 

[Overland Hadley]

Neat idea! I wonder how much the bladder is going to expand if you drive the truck from sea level to 8000 feet?

Interesting product.

In addition to elevation change I wonder how it would handle temperature change. My truck sees a range of more than 150 degrees F, sometime in the space of a couple days. (I have a tendency to drive south in the winter)

 

[Overland Hadley]

I was wondering about this exact same thing when I did mine. It seems like you'd be better off with the pressure in the diff open to the atmosphere, so that you don't have the tendency to create a vacuum and let liquid creep past the seals (as ntsqd mentioned).

So does the stock breather have a one way valve?
Sorry, I am still not sure on this.

 

[soonenough]

So does the stock breather have a one way valve?
Sorry, I am still not sure on this.

Yes, barring the possibility that it is not sealing properly, the valve only allows pressure to exit the differential, but does not allow air to enter.

I saw a picture once of someone that either disassembled or cut away the diff breather, and it's basically a housing with a spring on top of a little seal plate that seats against the housing. The internal pressure of the differential works on the bottom side of that little seal plate, and when enough force is created to overcome the spring force, the seal plate is lifted off seat and air is allowed to burp out. However, there is no way for air to go the other way around the plate.

 

[Photog]

The problem with this one-way-valve is, a quick dunk in the cold water will create a stout vacuum in the cooling axle housing, and try to pull water in past the axle seals. This could bring dirt into the seal too. Either one of these will eventually cause problems.

 

[soonenough]

The problem with this one-way-valve is, a quick dunk in the cold water will create a stout vacuum in the cooling axle housing, and try to pull water in past the axle seals. This could bring dirt into the seal too. Either one of these will eventually cause problems.

Exactly! That was my concern with simply extending the diff breather, as it doesn't eliminate the problem with the design. However, the front diff and transfer case use the exact same breather, so I guess they are probably susceptible to the same problems. I'm assuming that design engineers at Toyota have considered this possibility and don't think that it will be an issue, so maybe we shouldn't be worried.

I do remember reading an article somewhere about Land Cruisers / Rovers (can't remember which) that were having water ingress issues during water crossings, and after changing the one-way valve out for a simple filter, everything was fine. As much as I'd like to think that Toyota designed it this way for a reason, I just can't see how this wouldn't create the exact problem Photog is describing. I did read somewhere that part of the SOP for water crossings should be to stop and let the differentials cool down before submerging them, which would minimize the difference in temperature between the diff and the water, hopefully creating a smaller pressure drop inside the housing.