Toyota Breather Plug - 90930-03136 - is a one way valve - check your differential breather mod

I am in the process of doing this mod to my 2007.

I received the valve. I popped it into my mouth, when I blow on it, air escapes. When I suck on it, it is blocked.

Toyota Breather Plug -

$8 90930-03136 Toyota Breather Plug - 90930-03136

90930-03136 is one way.

As a result, I don't think that if you used this part on the end of your hose behind the fuel door or tail light or whatever you solved the underlying problem.

When the differential is hot and is quickly cooled you need air to get back into the differential but not by bypassing seals or coming in via a valve on the pumpkin.

Something like a crankcase filter would work nicely instead.

 

What one do we need?

 

I've mentioned that these are one-way valves on here before myself.

You really don't need anything at all on the end of the breather hose if you've extended it. Just be sure that the end of the hose is pointed downward so dust/water can't settle into it (I inserted a length of soft copper tubing (plumbing section in Lowe's, etc.) into the end of the hose on mine so it stays in a bent-down position).

 

I just used an inline fuel filter from a small lawn mower type engine for the rear diff breather. I also pointed the inlet downward for dust and water ingress prevention.
I'm working up a scheme for the two breathers under the hood using one of those sintered brass filters. Its overbuilt for sure.

 

It isn't a 1 way breather it just only allows a slow airflow in. There is no spring or valve the breather is just a hose barb with a metal cap on it. When you suck hard the metal cap gets pulled against the plastic but since there is no sealing material a small amount of air still gets through. When functioning as a breather the only way you could ever have enough airflow to create a similar situation is if the entirety of your diff fluid was draining out.

 

Well sense thousands have been used the last 15 years I think it’s safe to say the Toyota or Dorman is fine.

 

(Just a theoretical discussion for fun)...

but if you quickly dunk your gear boxes in cold water and get a quick contraction, you could theoretically get water sucked in via seals if that vacuum pulls the cap closed. I think the pseudo-one-way design is really for a warming gear box that needs to have hot air exhaust.

 

You should go take one apart.
There is indeed a small spring, and a rubber disc inside there. The spring keeps very light pressure on the rubber disc inside the valve, thereby allowing light air pressure to escape, but sealing when no pressure (or a vacuum) is present.
You can see the cap, spring & disc in the background in this pic of a rear valve (the one from my front (the part in question here) had the same spring & disc in it):

 

The volume reduction in the gear box even from way over heated to ice cold isn't that large. I just can't see it creating any real suction. Even with a large amount of suction air is getting in to equalize the pressure. My bigger concern is dust getting into an open system. The desert dust around here makes its way into everything.

If you are concerned pop the metal cap off and add some notches to the end of the plastic piece then pop the metal back on.

Personally I am going for way overkill on the diff breather and recently picked up a 12mm intake filter off aliexpress to slip over mine. Kind of big but should keep the dust out. I am going to place the breather behind the bed inverter outlet to give it some splash protection. Havnt decided if I am going to pop the metal cap off first or not. Only cost like $3. If anyone is starting from scratch they could just go with a hose coupler instead of bothering with the toyota breather if doing this.

 

The original breather is constructed like this but I ordered Toyota Breather Plug -

$8 90930-03136 Toyota Breather Plug - 90930-03136

90930-03136 from my local toyota dealership and it only consisted of a plastic hose barb and a metal cap. I did disassemble it.

 

They must've changed it then (assuming that's the same pt# for the front diff breather). The front diff breather from my 2018 was identical to the rear other than it had a plastic base w/hose barb rather than a metal threaded base.

 

The toyota parts system doesnt show my truck (2022 tacoma trd off-road) using the 03136 part number at all. 90930-A3005 i believe is the front diff and 90930-03220 for the transaxle.

 

Looks like it was the breather used up until 2016. From https://www.toyotapartsdeal.com/oem/toyota~plug~breather~for~front~differential~90930-03136.html

 

is there a rationale where we don't want air to come IN easily? Why constrain incoming air? filter it, sure, but constrain it? why? There's no reason for that I can find.

hence, open them up and filter them.

 

Moist air coming in and condensing and dust seem bad but the only other reason I can think of is that a sealed system would leak slower than one at atmospheric pressure if there is a leak. They designed them as essentially sealed systems but added an exhaust so they wont blow their seals when overheated. If there werent documented issues with that in the rear I wouldn't bother second guessing them but some things are just designed more for on road than off.

 

Anyone have links for a Aussie style breather kit for all 4 hoses that’s available in the states?

 

So is the censuses is the Toyota 90930-03136Plug is good to use.

 

Yes

 

I went with this as well. Bivalve and dust screen.

 

Well I'm sorry if I'm missing exactly where you are placing the filter. But if you fit it remove the cap and place the filter over breather directly on the axle don't you think water could enter the dif ? The hose extension kit look way better imo.