Contemporary take on rear differential breather mod

Ok, I know there are many threads on this topic and they don’t all agree. So, I thought I’d post how I raised the rear differential breather on my 2021 Taco and why I did it that way…

First, I decided to vent it high up behind the driver’s side tail light. I don’t have a driver’s side bed cubby (SR5) and even if I did, I would be concerned it would be a dust collector and I wouldn’t want to drill holes in it.

Next, I decided to go with the parts that made the most sense after reading and watching about 100 posts and videos on the topic. Here they are…

• OEM Toyota differential union.
• Dorman differential breather (don’t use the original breather from your differential - it will only exhaust pressure and won’t take in air).
• 7.5’ of 5/16” ID fuel line (don’t listen to anyone who says you can get away with 5-6’. It won’t be enough). I also don’t think 3/8” is the correct ID as some have suggested.
• 2 stainless steel hose clamps.
• A 1/2” rubber-insulated wire/hose clamp (to bolt the hose to the hole in the bracket behind the tail light).
• A stainless steel bolt, 2 ss flat washers and a ss lock nut (to bolt the above insulated hose clamp down).
• Black, UV-resistant zip ties to secure the hose.

Rather than list the part numbers, here’s a picture of them all:

And here is how I did it…

1.) Clean the original breather and the area around its threads with wd40. When I removed the breather, there was a pretty strong suction in my differential, which would have pulled in dirt (it also confirms that these differentials do create suction which can and will pull in water.

2.) Remove the original breather with a 14mm wrench. Mine was on very tight, so I used a hammer to tap the wrench a few times.

3.) Put a bit of Teflon tape on the differential union and threat it into the diff. (Don’t overdue the Teflon tape and be careful not to knock dirt into the hole. Also, don’t over-torque the union. Just snug it down tight.)

4.) Put the ss hose clamp over the union, then press the fuel line /hose onto it. Tighten the hose ss clamp without over-torquing it.

5.) Remove the driver’s side tail light with a 10mm wrench or socket. Just the tip and bottom screws and don’t be scared to pull the tail light off. It will pop out of it’s brackets. Put it on the tailgate so you can work behind it.

6.) Run the fuel line hose along the wire harness on the frame from the differential to the hole at the bottom of the tail light area. Put it through that hole and up into where the tail light goes. Be sure to leave a decent amount of slack above the axle so it can accommodate axel movement and articulation.

7.) Put the hose behind the metal bracket behind the tail light (the one with a hole in it) and measure about an inch above that bracket and cut off any extra hose (assuming you have routed it along the frame with sufficient extra slack). Once you do that, take the hose out from behind the bracket and put a ss hose clamp on the hose and install the Dorman breather, then tighten the ss clamp.
Once you’ve done that, put the insulated hose clamp onto the hose just below the ss hose clamp.

8.) Now, put the hose with the Dorman breather on it back behind the metal bracket (the one with the hole in it). Next, align the hole in the insulated hose clamp with the hole in the bracket and bolt it down with the nut facing away from the tail light. Use a flat washer on each side. When you bolt it down, be sure the Dorman breather is visible at the top of the bracket, but make sure it isn’t touching anything (you don’t want to obstruct the breather). This part of the process can be a PITA because you need to get a wrench behind the bracket. But it’s worth it because you want the breather as high up and away from the tail light as possible. Less chance of creating obstructions, higher away from any water, and hidden from dust.

9.) Zip tie the hose along its route from the tail light to above the axle.

10.) Put the tail light back on (don’t over-torque it) and have a beer.

NOTE: These are my opinions only and I am not a mechanic. I take no responsibility if you damage or destroy your truck.

 

What’s the part that you did differently?

 

Pretty standard really.

 

Nice instructions.
There's a reason Toyota ran vents on other driveline components and just a check breather on the rear diff.
Agin, nice write up though.

 

Yeah to save money on production.

 

In 2010 I was very timid to get the rear diff of my new 4Runner under water. Too many horror stories. Well, I had to do it to get home through a flood. Next day I did a rear diff fluid change. No water.
Several months later I did it again. Again a rear diff fluid change. No water.
Now? I don't even think twice about it. The breather works as advertised.

 

Looks good OP!

 

See, you should have said that first! Then we would have all known you were full of shit because everyone knows the best mods are done with cross threaded bolts, duct tape and a case of beer!

 

Try going through peanut butter mud then see if the minute negative pressure the gas shrinkage from thermal shock generates has enough force to overcome the natural concrete slurry it's now been force fed.

Beyond that just because something already works doesn't mean it can't work better.

That's like Germany's motto ain't it?

 

There isnt enough thermal pressure to do anything

 

ARB makes a breather kit..zero pressure, zero vacuum, has a filter, a complete kit..with everything you need, hoses, zip ties ,self drilling screws, watch the install videos,(-running for tacos)…and add up to 4 lines..!
I had mines install last week..
Do not trust the factory diff breathers…Water leak in my diff $4,100 replacement 2019 TRD mud , dirt can keep the one valve clogg….if you take the diff under water, a deep crossing…it can leak water in…?

I trust the ARB breather kit…
Aloha

 

Nice write-up! I've been thinking about this mod for quite a while - waiting for the warranty to expire.

 

Nice article, I liked it and will do it when I get my shop back (moving). But, I'm going to show my ignorance here ...

The front diff goes under water sometimes as well, yes? Is there not a breather relocation issue here as well? Could someone explain this or, provide info for front relocation too, please?

 

The front is a 8” clamshell IFS diff. Front diff is positioned higher than the rear diff so the breather by default is already a bit higher so there’s not as much concern there. The rear diff is the lowest one an easiest to do access wise.

 

Thanks! I live in Phoenix and water crossings are not as much of an issue here as in Florida. However, I hand-grenaded the rear diff in my Chevy decades ago from boat launching (?) and certainly from crossing the Verde River here many, many times. So, it can still happen in the desert. I didn't know any better at the time and don't want to repeat that. And, I'm thinking of buying a boat soon and, perhaps revisiting the Verde River crossings again some day.

 

I did my rear breather a few years ago almost exactly as the OP did. Only change I made was to install a small sintered bronze fuel filter as my breather behind the drivers tail light.

I plan to go through the rest of the truck and elevate the MT, transfer, front diff, and ADD a bit better than how they came from the factory. As well as add sintered filters as well.

 

Just look for a small bronze sintered fuel or air filter on Amazon that fits your fuel hose ID.

 

Just installed the knockoff ARB breather from Amazon. Same stone filter housing, lines and fittings

$46 Differential Axle Breather Replacement for ARB 170112 Kit Compatible with Drivetrain Assemblies, Differentials, Transmission and Transfer Case of 4×4 4WD Accessories

https://www.amazon.com/dp/B07V3C77HY?_encoding=UTF8

 

And Dry climates tend to ruin seals, so the breather kit is a good idea in dry climates

 

Yes …the ARB diff breather is a bit more pricey…but what it offers in its tech designs ..& proven in the Outback’s of Australia…and under $80.00…. And most of us this is a one time buy…I would say the “Best of the Best”…plus a replaceable filter…
Aloha,