DIY: Rear Differential Breather Mod

Isn't this the same breather that is removed from the rear end? Just use the one you take off

 

For more information go look at the 32 page thread on the same topic at TacomaWorld....

 

That link takes you to the site but not the thread

 

Sorry, I just typed in TacomaWorld and it created a hyperlink, I think from my ipad. Here is the link:
https://www.tacomaworld.com/threads/my-differential-breather-mod-photos.111954/

 

I would advise against using teflon tape on this fine of a thread. And even more so with it being a hot metal with oil. The threads are M10-1.0mm and the tape isn't going to do much of anything. After the pumpkin heats up, that tape will soften and the threads can move. Look at your factory breather, no tape. If you want a threadlock, use a single drop of 242 on it. But clean the surfaces of both parts well. Threadlocker doesn't adhere well to oil, grease and dirt.

 

Diff breather installed?
https://www.youtube.com/watch?v=7uaoiLaCdc0
*not my truck

 

Stupid question but is anyone worried about having a higher pressure drop between the diff and vent/breather due to the longer hose and filter (if using)? There was a theory in the discussion on the rear diff weep that one potential cause is the stock vent is too small and the diff leaks because it pressures up due to not being able to vent quickly enough. I'm not saying they're right, just thinking about this mod and wondering if it carries any risk of exacerbating that issue. Thanks and sorry for my ignorance.

 

I did mine up into the driver side rear taillight just over a year ago. Did it because I have a couple of creek crossings I make on a yearly basis for camping/hunting plus whatever puddles I get into while trailing around Ontario. Just changed my rear diff oil a few months ago... no water and turned out the oil was perfect and probably didn't need to be changed.... derp.

Living in salt/bryne country and with the rear axle getting submerged at least a few times a year I have had 0 issues/problems. I agree that people are overthinking this... it's just a vent to relieve some pressure and if you are going to dunk the rear axle you don't want water getting in.... just my 2cents

 

Step by step video, it’s very easy!

https://youtu.be/gyteuG5NbEs

 

For those who still wonder, consider the following, in addition to the pressure differential question raised by 223 (personally I do not see how the several foot difference could affect the pressures enough to make a practical difference):

Why did Toyota include a one way “vent” on the rear if a “breather” is appropriate?

If you do the mod but use the factory “vent” (as opposed to a two way “breather”), what have you added to the system by including a hose connection?

Why do some Toyota differential “vents” or “breathers” allow air to pass one way only and others both ways.

 

Next mod

 

Anybody in the Denver area have their old rear diff breather valve? Mines busted and no dealer in the state has in stock...

 

$8 Toyota Union - 90404-51319

https://www.amazon.com/gp/aw/d/B00P2S0TKQ?psc=1&ref=ppx_pop_mob_b_asin_title

$34 The Stop Shop Fuel Injection Fuel Hose 30R9 5/16" I.D. 7 Feet USA w/ 4 Clamps

https://www.amazon.com/gp/aw/d/B06Y273SF8?psc=1&ref=ppx_pop_mob_b_asin_title

 

Simple question. Did the OEM vent that you pulled from the diff seen a lot more “loose” than the new breather (

$6 90930-03136 Toyota Breather Plug - 90930-03136

90930-03136)?

Just from a visual inspection, I don’t see how the new “breather” (90930-03136) would allow much airflow when needed.

The silver cap on mine is very tight.

 

It was asked earlier, but didn’t get a reply and I wanted to try again.

What is the benefit of running a 2-way breather and filter over just a filter? I just can’t picture the benefit of a 2-way breather over an open line, assuming both have a filter.

 

if the original vent is only venting (net positive pressure) how does water even get in? Also the problem with the two way breather mod is that sucking in moisture from ambient air that will eventually accumulate in the diff. There's a reason why oil temp need to reach operating temperature before you shut down the engine. Unless proven otherwise I'm going to assume all of these mods are completely a waste of time and potentially detrimental in the long run.

 

I'm not a physicist, but logic tells me the vent does not go from open to 100% sealed and closed instantaneously. Also, I think a submerged open vent with little to moderate pressure would still allow water infiltration. My thinking is these vents work like a dry snorkel... you can probably keep most of the water out but maybe not all of it. The other concern is rapidly cooling the diff fluid by submerging the rear axle in cool water potentially creating a vacuum. You would then be relying upon a submerged vent seal to be good enough to prevent sucking in water.

I join you not advocating use of an open or two-way breather. I attached a standard type breather vent to the hose behind my taillight assembly.

Bottom line, if extending the breather valves to a higher location was detrimental, why would Toyota do it for the front diff and t-case on 4x4 models?

 

That depends on the axel seal design. If the diff seal were design to run with a slight positive pressure then that's what it is. The transfercase and front diff mostlikely use traditional seal where atmospheric pressure is needed. So by running a two way mod that pressure is no longer there and again can also cause problems for the seals from preventing water intrusion from the outside. Extending the diff tube with the same one way valve is undoubtedly a waste of time regardless whether or not you believe in the positive pressure seals.

 

Not a physicist either but how could the valve possibly be one way? Isn't the issue here about how air get's into the diff when it is suddenly cooled by a water crossing, puddle, etc and causing the air inside to cool creating a vacuum and air to flow from outside into the differential? Why would moving the source of this air from the top of the differential to a source higher up not improve this scenario?

 

I'll be pulling mine off in the next few days (probably this weekend) when I run the diff breather extension so you're welcome to it if you want to cover shipping. Off a 2018 with about 13k on it.

 

So the vent is a spring loaded rubber gasket design. The spring presses on the seal at a certain force measured by its spring constant. When the expanding gas exceed the spring force it vents. This spring pushing down on the rubber gasket also prevent cooler ambient air and water from entering. This is why the differential vacuum theory makes even less sense to reduce the diff positive pressure that is pushing against the bearing seal to keep water out. Under submersion this one way valve gain a net negative spring pressure (more force pushing on rubber gasket) and allows the diff to maintain its positive pressure. As for your mod when moving it up higher this doesn't change the dynamic so much as it is a waste of time as stated earlier.

 

It absolutely is not a spring loaded rubber gasket design ... have one in my hand now for the extension mod and if you shake it the metal cap on the end rattles. Also from my amateur testing it allows air in and out and for the most part is an open breather design with the metal cap being nothing more than a cover to keep stuff out.

 

According to Toyota, the breather is the same part number whether it is front or rear.

Part Number: 9093003097
Supersession(s): 90930-03097

BREATHER (FOR FRONT AXLE); BREATHER (FOR FRONT DIFFERENTIAL); BREATHER (FOR REAR AXLE).

Fits Tundra (2007 - 2012)


https://parts.deserttoyota.com/p/To...igin=pla&partnerDevice=c&userLocation=9051700

 

Thank you Adam!

- Adam

 

Not sure if they have a different design between your model year but I have the 2020 model and it has a spring loaded design.

 

Well like the lack of a separate transmission cooler maybe Toyota redesigned the part and now you'll suck in water through your axles. I'm sure ToyotaCare will take care of it for you!

Also here is the part number of the version with the barb for a hose. Even Toyota calls it a "breather" and not a valve. By design a breather will allow exchange both ways while a valve only allows flow in a single direction.

https://www.sparksparts.com/oem-parts/toyota-plug-breather-9093003136

 

Muh android auto apple CarPlay > than transcooler. I dont even get my bed dirty . Just kidding though yeah I plan on doing the tranny mod later.
If your rear diff is running a "breather" its definitely a good idea to move it higher. Else just leave the thing alone.

 

I would like Carplay but it's cheaper and better to go aftermarket. Sorry bro but you have the same breather on your rear diff as my 2018 so if you're planning on leaving the mall parking lot you might want to get it out of the water

 

Nope my diff valve is one way spring loaded, I checked with my tounge. I put 35s on my rough country lift for mall crawling thank you very much.

 

Well as long as you're happy I guess!