3rd Gen Tundra Diff Breather/Axle Vent

I read on here about the rear diff on the 3rd gen Tundras being a simple vent on top of the differential, and I was able to locate it on my truck and and will be relocating it to a higher position. My question is about the front differential. Does the front differential breather have a hose relocating it up higher than the top of the diff? Does it even have a breather? I can't seem to find any information about the front diff breather online. I am hoping that someone has investigated this on their pickup. I would go look at mine real quick, but with the skid plates it is hard to get in there to investigate it.

 

No real need to do anything up front. The breather is extended and mounts up a bit higher on the body.

 

That is great info, thank you! Interesting that they would extend the front breather up but not do the same with the rear.

 

Can you please post some pics after you extend the rear diff breather ? Thank you.

 

Here’s a few pics for this kit that extends it behind the brake light.
https://irontrussfabrication.com/products/2022-rear-differential-breather-relocation-kit

 

I sent mine straight up with some 5/16 fuel line and Toyota union

$9 90404-51319 Toyota Union - 90404-51319

90404-51319. I may reline it and send it like the above post

 

Thank you very much guys

 

Yeah I'll see what kind of pics I can get when I do it. I pulled the factory breather off and measured the threads and it appears that it is 1/8-28tpi BSP threads. I initially thought it might be 1/8-27tpi NPT threads but it was not. I can post the components that I used once I complete it.

 

I got the diff breather relocated finally. I'll post links to the products that I used. I ordered the hose barb with 1/8 BSP threads off of Amazon because I could not find one locally, due to the BSP threads. The hose barb at the axle is for 1/4" hose and the breather has a 5/16" hose barb, so I got an adapter. I ran 1/4" fuel hose from the axle to the adapter right near the breather, but then I added the adapter to transition from 1/4" to 5/16" right before the breather. If you can find an 1/8-28tpi BSP fitting with a 5/16" hose barb that would be ideal, and could avoid the need for the adapter. But this should work fine.

1. 1/8-28tpi BSP hose barb:

$7 EDGE INDUSTRIAL 1/4" Hose ID to 1/8" Male BSP BSPT Straight Brass Fitting Fuel / AIR / Water / Oil / Gas / WOG (Qty 01)

https://www.amazon.com/dp/B07CX58JBP?ref=ppx_yo2ov_dt_b_product_details&th=1
2. Breather:

$6 Dorman 924-284 Front Differential Vent Breather Compatible with Select Lexus / Toyota Models

https://www.amazon.com/dp/B06XHBY38X?ref=ppx_yo2ov_dt_b_product_details&th=1
3. 1/4" to 5/16" hose barb adapter:

$7 Beduan Brass Hose Barb Reducer, 5/16" to 1/4" Barb Hose ID, Reducing Barb Brabed Fitting Splicer Mender Union Air Water Fuel

https://www.amazon.com/dp/B07PMQDLZ6?ref=ppx_yo2ov_dt_b_product_details
4. 10 ft of 1/4" low pressure fuel hose. I used just over 8 ft of it.
5. Hose clamps (I had a random assortment laying around).
*EDIT - 6. Short length of 5/16" fuel hose.

Now for the pictures.

The full circuit laid out and loosely attached:

The original breather:

Now with the new hose barb:

And with the hose attached:

The finished breather hose with slack in the line and secured to the electrical cable:

Routing it over the frame crossmember toward the rear of the truck:

And the finished breather inside the taillight opening. The picture was taken through the opening of the taillight with the light removed. I should have gotten one while standing back a bit farther.

 

thanks for the info @CORam

only place i can find 5/16 barb BSP fitting is MacMaster Carr

https://www.mcmaster.com/catalog/130/342/1075T307
Brass Barbed Hose Fitting for Air and Water, Straight Adapter for 5/16" Hose ID x 1/8 BSPT Male
1075T307
$11.77 + $8.28 shipping
$20.76

Would be interested if anyone can find the Toyota Union, screw in barb fitting part number like we've used on previous generations 90404-51319


Edit: just get Toyota part noted by @TundraTT (sorry missed your post above) much cheaper. Anyone with previous Yota truck/suv should be familiar with this part it’s been the same for 60 years

 

Read above… same union fits

 

Interesting about the McMaster part. I originally thought that the breather was 1/4" hose and when I looked on McMaster I saw that the 1/8" BSPT x 1/4" hose barb was $20 + shipping for a pack of 10 of them, so I looked elsewhere. Now that you point that out, I would probably go with the McMaster part that you posted and then could skip the 1/4" to 5/16" hose barb adapter. That would be cleaner. Thanks for posting that.

 

TundraTT, that is good if you confirm that that Toyota union fits. I had seen that part on Amazon early on but couldn't confirm the threads on it, so again I looked somewhere else to ensure that I got the right BSP threads. And I don't think I saw the link in your post before - that would have saved me some time.

 

Thanks for the write up. Did this today with the Amazon toyota union, reused the original breather vent.

 

An interesting observation from when I relocated the breather. As I unthreaded the OEM breather from the axle there was a very distinct "pffft" sound as I got toward the final threads. Gases obviously passed by the breather as the threads opened up. I couldn't tell if the gases flowed into or out of the axle, but it is quite concerning and has me believing that the OEM breather is defective. It happened twice - once when I removed the breather to measure the threads, then I put the breather back on. Then weeks later I pulled it again to actually relocate it and it did it again. Both times the truck had been sitting in my shop for days prior without having been driven.

This came to mind as I saw that several of you on this thread re-used the OEM breather and I hope you don't have the same issues with yours. I have not opened up the new breather to check for a release of gas, but I plan to check it for the same issue at some point.

Did anyone else experience this release of gas upon removal of their OEM breather?

 

No noises when I pulled mine. Checked the OEM before putting at hose end - all good.

 

so I had ordered this same Toyota union off Amazon, but it seems very hard to screw in. I’m worried the thread pitch isn’t correct. Don’t want to strip anything out.
Was yours hard to screw in?

considering getting the barbed union brass fitting shown up above by CORam.

 

Take the oem breather and find a nut that matches the rivet. Test both of them on the same nut.

 

great info and very clearly laid out in the pictures thanks!

as you can see I mentioned above I had ordered and tried to use that Toyota Union

$9 90404-51319 Toyota Union - 90404-51319

90404-51319 and I could only advance it a couple of turns before it became much more difficult that I felt comfortable with. Don’t want to strip out the threads.

This made me concerned that the thread pitch may not be correct, and I don’t know if a good way of measuring thread pitch other than, “if it doesn’t go, don’t force it because it’s probably wrong”. I’m glad to see you found that brass 1/8” hose barb had the right pitch at 28 tpi. Good thing is Amazon can get one of those to me cheap by tomorrow so I will try that instead.

I did have one other question for you though. Your picture of the assembled breather tube shows two separate pieces of tubing connected together. The are I circled in red below. Is there any reason in particular you did it that way? Was it just that your first piece of hose wasn’t quite long enough or is there something I’m missing?

Thanks again for sharing the tips on the breather relocation.

 

You bet! I pulled the OEM breather out of the axle and measured the diameter of the threads and used thread gauges to measure the thread pitch. When I first pulled the breather I assumed that it was 1/8" NPT threads, which are 27 tpi, but the thread gauge for 27 tpi clearly was not correct, but 28 tpi was correct. That is how I determined that it was BSP threads and not NPT. They are so similar in diameter and in thread pitch that it is difficult to tell the difference without thread gauges. Your experience leads me to believe that the fitting mentioned above from Amazon may actually be an NPT fitting and not BSP, which is what I feared.

I considered buying that union off of Amazon, but I could not find the thread pitch specs for it so I decided to go a different route in fear that it would not be the correct pitch. I wanted to buy parts that were exactly the correct parts, per the stated specs. The BSP fitting threaded in nicely.

As for the 1/4 to 5/16 transition - the hose barb at the axle is for 1/4" hose and the breather has a 5/16" hose barb, so I got an adapter. I ran 1/4" fuel hose from the axle to the adapter right near the breather, but then I added the adapter to transition from 1/4" to 5/16" right before the breather. @gearnuts found an 1/8-28 tpi BSP to 5/16" hose fitting on McMaster, part number 1075T307. I would go this route if I did it over again. The problem was that I thought that the breather was for 1/4" hose when I bought it, so I planned everything for 1/4" hose, but then the breather turned out to be designed to accept 5/16" hose, so rather than return the fittings and hose, I just picked up the adapter to 5/16" hose and ran a short length of 5/16" hose to the breather at the end. Plan everything for 5/16" hose from the start and you are golden. Or find a breather that has a 1/4" barb. Or do what I did and it will work but won't be as clean.

If I did it over again, this would be my revised parts list (much simpler!):

1. 1/8-28tpi BSP hose barb (for 5/16" hose):


https://www.mcmaster.com/1075T307/

2. Breather:

$6 Dorman 924-284 Front Differential Vent Breather Compatible with Select Lexus / Toyota Models

$6 Dorman 924-284 Front Differential Vent Breather Compatible with Select Lexus / Toyota Models
https://www.amazon.com/dp/B06XHBY38X?ref=ppx_yo2ov_dt_b_product_details&th=1

3. 10 ft of 5/16" low pressure fuel hose.
4. Hose clamps

 

Old post but I definitely heard a pressure release when I cracked open the fill plug on my 22. Truck had been sitting for hours too, diff was cool to the touch. Replaced the gear oil so I cracked open the fill plug first, noticed the pressure and then drained the oil. Never dawned on my that the breather might be stuck.

 

Interesting that you had a similar experience. I haven't heard of issues with axle seals or anything on these Tundras, so I am not sure what to make of it. But I don't like the idea that the axle is sealed and holding pressure. I still need to check my new relocated breather to see if it is working.

 

I did my rear dif oil on Saturday, and same pressure release. I will need to check that breather. Pretty weird.

 

https://irontrussfabrication.com/products/2022-rear-differential-breather-relocation-kit

I used this kit.

 

was it pressure or vacuum release? I just remember the hissing but now that I think about it, I'm not sure if I felt air coming out.

 

Officially I would think the thread is either M10-1.0 or 1/8" BSP but its close enough for gov't work
NPT = National Pipe thread Tapered, and it is 0.407" (10.2mm) OD with 27 TPI (threads per inch)
M10-1.0 is 10mm OD and 1.0 mm thread pitch (or 25.4 TPI)
BSP = British Standard Pipe thread, and it is 0.407" (10.2mm) OD with 28 TPI (threads per inch)
So you can see the three are VERY close and for the few threads in the housing and the fact that pipe threads are tapered (meaning the male thread starts out small and gets larger in diameter as it threads in, female thread is the opposite) an 1/8NPT thread fits fine for this low pressure, low stress application, YMMV.
For an even better fit, run a 1/8" pipe thread tap down into the housing, apply grease to the tap to hold the few metal shavings it'll cut.

$12 Toyota 90930-03136 Toyota Breather Plug - 90930-03136

Toyota 90930-03136: 5/16” Barb
Toyota 90930-03031: M10 x 1.00 Thread Pitch

$9 Toyota 90404-51319 Toyota Union - 90404-51319

Toyota 90404-51319: M10 x 1.00 Thread Pitch, 3/8” Barb
Toyota 90404-51026: M10 x 1.00 Thread Pitch, 1/4” Barb
Nissan 38323-C6010: M10 x 1.00 Thread Pitch, 3/16” Barb

At first I started with a Nissan breather, I didn't discover the Toyota breather with the barb till later. I personally use the Toyota 90404-51319 with the 3/8 barb. I drill out the hole as large as possible to increase flow in the event gear oil does enter the line.

This mod is good but can also cause problems if not done properly. The purpose of the vent is to allow excess pressure to escape the housing, if you have a plugged breather the pressure will force its way out of the axle seals causing a leak at the diff end.
Gear oil is thick as hell, in the winter it's as thick as molasses. Any amount of gear oil in the line will essentially clog the line.
The one thing I would not do is reuse/use the stock fitting after extending the line. The fitting has a spring and a rubber disc under the cap. The spring keeps pressure on the rubber disc forcing it down to seal off the fitting from water/contaminates from entering the housing. The springs rust and over time get stuck, some open, some closed. As an avid off roader when I extend breather lines on my trail trucks I finish it off with a small engine gas filter like this.


On my competition buggy I've gotten rid of extending the line and presently use something like this. After rolling over and having the truck sit on it's lid I've clogged up those extended lines with gear oil. The bellow type breather allows the gear oil to only have to travel through the fitting, not a 3' line.

 

There was hissing. Hard to tell if air was rushing out. It was odd though, very distinct. I had the spare still in there when I took the fill and drain out. So access was tougher. I ended up removing the spare to fill.

 

yeah, space is tight with the spare up there. I used amsoil bags, so I was able to squeeze them like a toothpaste tube.