Sealed Trasmission fluid change

Toyota has 2 way breathers only. Rear differential is 2 way, that's why it needs to be extended if you wheel your truck.
One way breathers do not work in parts that generate heat and varied pressure: AT, differentials.
A differential or transmissiom without a breather will bust its seals.
How much mechanical knowledge do you have?

 

Oh man, This is wild. Can you reiterate your message about the rear diff breather and suckin water through the axle seals?

 

Differential breather is on top on the left, above the pumpkin, almost on the axle itself.

 

If a system has a one way breather, when it gets hot the air expands and some goes out. When it cools back off a vacuum is created. Exerting pressure on the weakest link, the seals.

 

Yeah agreed. Homeboy said it's a two way valve on the diff?

 

I think that was his point. It has to be a two way for that reason, because of expansion and contraction due to heat.

 

Right, but my point was, Toyota installs a one way oem. Why would they change it for the trans, front diff etc? I was exploring the logic of it.

 

I thought he was saying all the breathers were two way.

 

Well we know that's not true right? Or else the breather extension wouldn't even be a thing? The rear diff breather is basically a poppet valve. Spring on top, seal below it, vacuum only increases the seal. I could be seeing the whole conversation wrong though.

 

HIGHPSI is your run-of-the-mill know it all blowhard. According to him he’s designed everything from scratch and knows better than everyone. Except when he’s wrong which is rather often, and especially when he’s been drinking, which I suspect he has been tonight.

 

Well, I always thought the breather mod was to keep the breather opening above water during a crossing, because the valve was two-way. But I’m not educated on it because I don’t do water crossings and therefore I’ve never read up on the breather functions in detail.

 

It's interesting seeing vehicle maintenance from a heavy equipment perspective. Hydraulic fluid is often expected to be changed every 5000 hours, which is around 200k miles on a truck. It's common to only change it at 10k or just not at all. My old forklift had 10k hours on the last (and only) oil change and 18k on transmission, hydraulic, and differential fluid. We've got a press with over one million strokes on it and it only calls for oil changes every 10k hours, and I'm not positive it was changed every time it was reset.

I get it isn't an apples to apples comparison, but when the fluid being drained looks the same as the fluid it's being replaced in, it seems like a waste of money.

I bet if you sent a sample of your ATF to a lab they wouldn't find anything wrong with it.

 

The whole issue was what he stated in the beginning. Oil heats up, bypasses the breather, water crossing, oil cools down, creates a vacuum, water pulls in through axle seals. The mod is to switch to the TWO WAY breather, and locate it higher so water doesn't just simply pour in the top of the breather.

 

You being cute or what?

Here is a writeup on how to do it.

 

How is MarshallR’s advice any better than that of your daddy’s uncle? It’s still second hand here-say, not “real data” as you put it. MarshallR is afraid to put his 4WD truck in 4WD because it “will stretch the transfer case chains.”

 

That would make sense. I still believe that I’ve read about at least one breather on another Tacoma system that is two-way, stock. But I’d have to do some research.

 

I have sent my trans oil in and they didn't necessarily find anything wrong with it. But they don't have a lot of data points to compare against.

Here are my magnets from when I dropped the pan and cleaning a couple of them.

 

Diff breathers are one way and draw water through vaccuum through the axle and diff seals when cold shocked, that’s why people replace them with extended two way breathers.

 

https://www.tacomaworld.com/threads/question-about-diff-breather-mod-why-2-way.113451/

How much mechanical knowledge do u have??

 

Enough to replace ATF in my vehicles every 50K.
The only reason I brought up the rear diff is to show that there is no such thing as 100% sealed air tight mechanical part that has oil and gears.
Saying that ATF never needs to be replaced because AT is sealed and ATF does not oxidize is wrong.