Any Members in Arkansas?

Thanks Pete! Sorry I wasn’t clear about that bit @MatthewMay1 but Pete is correct.

 

Rainy weekend in the shop....making sawdust

 

I used a new factory diff breather, just located behind my tail light. Extended with fuel line because that's what I had lying around.

Edit: Something to be aware of is that there are breathers in the front as well. On my 1st gen they're mounted on the inside of the frame in the engine compartment on the driver's side. So even if you relocate the rear you still have to be careful not to submerge the front breathers. Although if you're getting to that depth there are a lot of other issues to be aware of. I think with my rear breather behind the tail light my front and rear breathers are at roughly the same height.

 

Not sure the benefit of one way valves. Hot diff air wants out, and then cools quickly and air wants in. I get rerouting/ extending the one way to prevent blockage from mud etc, so it can exhale but if it can’t inhale then it’s gonna go for weakest seal when rapidly cooled. I also get the shortened life of the fluid due to moisture but one way valve defeats purpose of the mod for water crossings.

 

What a dilemma. Quite a debate across the interwebs on whether to leave it open or use the one-way valve. All seem to agree to get it up higher and that a clogged vent is bad. In general, it seems that the main reason for the one-way valve is to prevent sucking in water under rapid cooling. Differing opinions on whether that would cause it to suck anything past any seals. I dunno, seems unlikely unless the seals were bad anyway, in which case you have other problems. Some manufacturers seem to use open systems, others the same cheapo type valve that comes on the Taco. With placement right on top of the axle, the one-way valve is certainly the better choice.

I'm thinking the amount of moisture from the air that can enter the system is about the same with either type of valve, it just enters at a different velocity. Either method is probably fine, and the differences aren't enough to worry about as long as you change the fluid at the recommended interval. I'll just keep using SuperTech dino gear oil every 30k and not worry too much.

 

I remember when I was doing research for mine there was a product that allowed for expansion and contraction but was sealed to outside elements. I didn't go that route because it seemed kind of gimmicky and cheap but sounds like it would solve both issues. I can't find a link to it right now.

Here it is:

$39 Trail-Gear Creeper Breather - Differential Breather Kit

https://www.amazon.com/Trail-Gear-Creeper-Breather-Differential-Kit/dp/B008OLPUJS

 

When will you be back in the states, Lee? @Enigma8246

 

Beginning of March at the latest but it may be sooner depending on how things go. If they go really well I may not be needed anymore. If they go really bad I may decide it's not worth being here.

 

Here's to hoping they go well and you get back sooner.

 

I can’t be certain about the Toyota valves, but for the company I work for they are technically considered one way valves, but will allow airflow into the component once a certain pressure difference is met. They’re also not designed to be submerged, so relocating hem high is important. The benefit of using this type of valve is that you don’t have airflow when you don’t need it. Because Toyota engineered their components to use this type of valve, I’d assume during product development they found it necessary. An open breather would be considerably more cost effective during production.

Lubricants break down rapidly when moisture is introduced. Different additives effect this, but in some cases it only takes a few PPM to cause a failure of the lubricant. This doesn’t mean your diff will lock up tomorrow, just that the oil is no longer protecting the components the way it was designed to.

Edit: I’m also skeptical about how much the fluid temp will really change when going through a water crossing. If anybody has a diff temp sensor I would love to test this!

Also, I meant to quote @TenBeers not Chip!

 

Thanks, Dave. I guess I will put the valve on. Best to listen to the only actual engineer in here.

 

Would the water introduced in the line be from condensation or humidity? If the OEM fitting does relieve some pressure, I can see where that would be better, depending on what amount of negative pressure is needed to pull water in thru the seals.

 

I just rigged up a little jig to test the valve in both directions. Don’t judge me on how crude it is! It’ll hold 5 PSI when blocked off so it’s fine for this test.

In the “out” direction flow was not restricted enough for me to measure it with a mityvac. In the “in” direction flow was blocked until .5-.7 PSI was achieved. Once the required pressure was observed, the valve continued to vent until pressure was equalized. I’d expect some threshold variance from valve to valve, but that should be about the same for all of them.

 

I'll look into this further, but I'm reading that Toyota is using two-way or 'open' diff breather ends on the front diffs in later 2nd gen and 3rd gen Tacomas, but the same or similar 'one way' mounted to the diff/axle on the rear since the FJ 40's were introduced. I'd like to educate myself on this more, but I've read numerous forums where people have used raised two way rear diff breathers using a simple filter for years and thousands of miles with no ill effects. And I have also read several instances where crossing an icy cold stream caused pressure difference sufficient to collapse seals, or at least was coincident enough to be considered suspect.

 

LOL, I'm impressed that you actually set up a real experiment! BUT WHAT DOES IT ALL MEAN?

I would have thought that the "in" direction would be open until a certain pressure was reached, and then it would close off. The behavior you describe is a bit different than I would expect, but it makes sense if trying to avoid being vented to incoming air unless absolutely necessary, and it should protect from water coming in through the seals.

I have a brand new valve at home (the Tacoma one looks a bit different) and will run my own (much lower-tech) experiment before putting it on. You can probably guess how I will do it.

 

Interesting. Of course, that icy cold water might also shrink the seal quickly. It's likely that both situations contributed.

I'm thinking that the additional tubing for routing it up behind the tail light provides a lot of extra expansion/contraction volume. I find it hard to believe there is that much movement of air back and forth.

I just thought of a new experiment. Get a balloon animal balloon and stick it on over the breather. Drive around and see how much it fills up, then stop and see how fast it goes down!

 

Those smarter than I could probably know more about this, but line length is important to consider. By raising the end, either way, there is air in that line. That volume of air carries properties that could impose effects if sealed. As pressures within the differential change, how will that mass of certain temperature, certain pressure air affect it? Condensation would be more of a concern in a sealed environment, true? If it's hot summer ambient temperature, then the line and diff is soaked in a spring-cleaning creek, that might make a different desiring open two way or OEM valve?

 

It should probably be said that we should all check on our differential oil regularly anyway...