4Runner Differential Breather Kit

Rear Differential Breather Kit Install (step by step)

ARB Differential Breather Kit 5th Gen 4Runner

5th Gen 4Runner Rear Differential Breather Kit Benefits, Install, Overview and Review

What is a Diff Breather?

A Differential breather kit prevents water from getting into your drivetrain when you are taking your 4×4 through water crossings. This is one accessory, you definitely want to install if you plan on trekking through some water.

Any breather kit is made up of 6-8mm tubing that connects the rear axle, differentials, transmission, and transfer case to a higher location mounted on your 4Runner. When hot, differentials, transmissions and the transfer case will heat up serving the need to vent.

When cold, these components contract which creates a vacuum of air. When you are going through a creek or crossing a river, things instantly cool down, which means you are likely to suck in that cold water. This cold water will eventually mix with your differential, transmission or transfer case oil and fluids with the potential of causing serious problems to your drivetrain or lockers. In our case, causing problems to the E-Locker.

When we take our 4Runners through a water, we are risking the drivetrain with the possibility of letting water mix with the drivetrain oil. If you go through a set or series of creeks, you will eventually go deep enough to where this will be an issue. With a big enough suspension system or lift kit, you can prevent this but it is always nice to have one just in case.

In any case, this is one of the most common off-road accessories that are installed on many 4×4 platforms. It is a cheap mod that almost ensures you will never have water coming in through your seals.

Different Types of Breather Kits and DIY Kits

ARB Differential Breather Kit 5th Gen 4Runner

Every breather kit is essentially the same, and most of these DIY parts can be purchased from 4x4parts.com and other 4×4/ off-road websites. But, we wanted to make our life a little easier and grab a name-brand, well-trusted and widely used kit that was made specifically for our models.

This breather kit is a pre-packaged kit that will give you everything you need. The ARB breather kit is a direct replacement for your OE differential breather. The OE differential breather is a short mounted assembly with a one-way steel valve. The problem with this valve is that it’s just short and stubby which opens up room for you having to drain your fluid later. Which no one wants to do.

By installing a breather kit, we will prevent water from entering our differential which will cause fewer headaches down the road. There are many owners out there who say you don’t need one and others who wish they had installed one. So, the choice is your’s but we highly recommend installing one if you are ever going to be out in the middle of nowhere crossing creeks and rivers.

Rear Differential Breather Kit Installation

ARB Differential Breather Kit 5th Gen 4Runner

Tools for the Breather Kit Install:

  • ARB Breather Install Kit (Part #170112)
  • Phillips Screwdriver
  • 14 mm or adjustable wrench
  • Cordless Drill (if mounting with self-tapping screws included in kit)
  • Pocket Knife/Utility Knife
  • Wire Cutters

Install Time:

  • 1 – 2 Hours

Whats In the Box?

  • Anodized Aluminium Manifold
  • 4 x BSP ports for breather lines
  • 1 x NPT ports for air filter
  • Air filter assembly
  • 4 x push-in fittings
  • 3 x BSP plugs for plugging unused ports
  • 8m x 8mm polyethylene tubing
  • 2 x self-tapping screws
  • 25 x cable ties

The Snail Trail 4×4 Install Video

Step #1: Locate Diff Breather and Remove

ARB Diff Breather Install 5th Gen 4Runner

Locate the differential breather. If you have a dirty 4Runner like mine, you probably want to clean around your breather as much as you can.

If you fail to clean the dirt around your breather, you may risk getting some dirt or debris inside your differential when you are installing the new breather.

Step #2: Install New Diff Breather (Shark Bite)

ARB Diff Breather Install 5th Gen 4Runner - Place New Diff Breather

Once you have wiped down the area around your breather, you can now remove the old diff breather and install the new shark bite. The shark bite is a fitting that comes with your ARB breather kit. The shark bit is the plastic piece that fits inside the fitting that bites down on the plastic tubing.

Step #3: Insert Breather Hose

ARB Diff Breather Install Step #3: Insert Breather Hose
ARB Diff Breather Install Step #4: 

Once you have installed the shark bite fitting, you can shove the first end of your tubing into the shark bite. Just shove the tubing straight in. This whole process is pretty simple, just make sure to shove the tubing straight in and not at an angle. One thing to keep in mind here is a little pro tip:

NOTE: Keep enough slack in your first loop connected to the differential to make room for droop in your axle. If you fail to leave enough slack in your tubing, you risk pulling the tube out of the fitting at full flex or even partial flex. Make sure you leave enough room in the tubing line to make up for your axle flexing left and right.

Step #4: Start Running Breather Hose

ARB Diff Breather Install Step #4: Start Running Breather Hose

After you have installed the shark bite fitting to the differential, you want to start running some tubing. You have quite a few options of where you want to run your tubing.

Some people mount the ARB manifold and breather on the passenger side of the engine next to the intake, some mount the ARB manifold and breather next to or near the battery and some even mount the ARB manifold and breather in the actual cabin where your spare tire tools are located.

The choice is up to you but we decided to mount the ARB manifold and breather up in the engine on the firewall next to our TRD Intake. Eventually, we will be running an onboard air system right here so hopefully, the breather does not get in the way.

As for the driver side of the engine bay, we will be installing the SPOD set-up right here. Things are tighter on the driver side of the engine bay near the battery so we wanted to leave as much room open as possible over there. So, that is why we opted to install the ARB manifold near our intake.

NOTE: Close your tubing off with blue painters tape so you don’t get any debris in the hose while running the tubing.

Step #5: Where to Run Tubing?

Step #6: Prepare Aluminium Manifold

ARB Diff Breather Install Step #6: Prepare Aluminium Manifold ARB Diff Breather Install Step #6: Prepare Aluminium Manifold

Once you have found your chosen route to run your ARB Breather Tubing, you want to pull all of the slack out and up through whatever side of the engine you are mounting your ARB manifold on. In our case, we chose the passenger side.

  • Pic 1. As you can see in the first image above, this is the remaining slack that we had coming out of the engine.
  • Pic 2. In the second image, you can see exactly how we plugged up the ARB manifold. You want to plug three holes and install one shark bite fitting in the remaining opening.

Step #7: Mounting Aluminium Manifold

ARB Diff Breather Install Step #7: Mounting Aluminium Manifold

Now, you need to mount your ARB manifold. You can do this by using the self-tapping screws that come in the box.

  1. Start by choosing your location
  2. Use a long nail or screw to tap the first hole with a hammer
  3. Use a drill bit just under the size of the screws provided to drill a hole
  4. Screw down your ARB manifold in the hole you just drilled
  5. Level your ARB manifold and mark another hole and then rotate your manifold aside
  6. Use your drill bit to drill another hole in the location you have tapped
  7. Rotate Manifold back in place and screw down provided screw
  8. Hand tighten into place

That’s it! This was the hardest part of the install but as long as you know how to use a drill, you are good to go. After you hand tighten your ARB manifold, you can cut off any excess tubing and insert the tubing into the shark bite fitting. Then, screw down the Air Filter Assembly (The plastic round part) and you are set.

Step #8: Connect The Air Filter Assembly

ARB Diff Breather 5th Gen 4Runner

ARB Diff Breather 5th Gen 4Runner

Once you have screwed down your Air Filter Assembly (The plastic round part), you are finished.

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Tanner H
Tanner H
2 months ago

I just installed my diff breather. I ran down the passenger side of the engine bay and down along the frame as well. I followed some wires along the inside of the frame until the rear wheel well. At points the tube is tucked behind the heat shield, and in places is touching it. Will that be an issue? Any risk of it melting with touching the heat shield?

7 months ago

Amazon says the ARB diff breather wont fit on a 2021 4Runner. I assume the OffRoad version would still need one? Do you have any suggestions? Thank you.. and I took your advice on my tire buying this week, so Thanks again!

2 years ago

Stock ’18 TRD OR here. Can this install be done without raising the vehicle with Jack stands, etc?

2 years ago
Reply to  Jeff

Yes you can. It’s just a little tight under the vehicle. I removed the spare tire to get more room and a clearer view of the rear diff breather. I also lifted the vehicle under the trailer hitch until the rear wheels were off the ground to get full articulation. This way I could get the correct length of tubing before I cut it.

Derek C
Derek C
3 years ago

Hi Brenan, Nice write up/video… and I know that you’ve said that maybe a future project, but could you speculate on if you would tie into the diff line the you just ran or run a line parallel up to the ARB in the engine compartment (seeing that there are several more ports), Thanks in advance…. (I am currently reading the link you posted in an earlier post, but it’s lengthy and discusses alternative products)

Derek C
Derek C
3 years ago
Reply to  Derek C

Spoke to Ryan at ARB and they suggested running another line using ARB part number 170113 (MSRP 36.00) and connecting into the mantifold you installed previous (part number ARB 170112).

2 years ago
Reply to  Derek C

Are you talking about the e locker? If so, how did this project go? Trying to do some research as well with running a separate tube to the arb filter

3 years ago

Hi Brenan,

Will you eventually connect the rear diff-locker to the breather as well?

3 years ago

Is the polyethylene tubing ok since is hard and possibly break or bend or would it be better to use rubber gas line that is pliable and thicker?

3 years ago

Isn’t there a breather on the locker as well that needs to be raised higher, separate from the actual diff?

Sara Arrington
Sara Arrington
3 years ago

Need one for front and rear?

2 months ago
Reply to  Brenan Greene

Brenan, any pics of these breather locations? I could probably follow them if I get under the beast but if you have some pics that would be great.

Questions or Comments? x