Rear Diff Breather Mod For 2nd Gen

[Red]

So I was bored and decided to do the "Rear Diff Breather Mod" for my 2nd Gen 4Runner. This is an extremely cheap and easy mod to do.

I used this write-up:

http://www.toyota-4runner.org/showthread.php?s=&threadid=123

Here are my pictures:

Connection to Diff housing.

Hose routing towards passenger side and up to the gas filler neck

routed just over the frame into the rear passenger wheel well.

Breather on end of line attached up near gas filler neck.

 

[hickory]

diff breather

Sorry about this stupid question. What is the benefit for the rear diff breather?

 

[Red]

Re: diff breather

Sorry about this stupid question. What is the benefit for the rear diff breather?

the stock diff breather often gets plugged from dirt and other debris, this happened to mine and it blew out the cap thing.

extending the rear diff breather allows you to submerse your diff in water without worrying about water getting into the diff also when the diff heats up the gases produced rise up through the hose and out the vent and any oil the escapes runs back down and into the diff.

 

[Ulfr]

It's a great and a cheap mod. I blew an oil seal on each side (and actually around the diff on the housing) because of a bad valve, but we could also call that a bad owner problem. ;P

 

[a red 4runner]

Greetings from 2016. So the rear diff is pretty simple. But if you're elevating your rear diff why would you not do your front? I haven't been able to find a whole lot about doing the front, but I've heard that you need a union fitting with a 90 degree bend in it to fit through the tight spaces around the front diff. Anybody done it?

 

[RonJR]

Greetings from 2016. So the rear diff is pretty simple. But if you're elevating your rear diff why would you not do your front? I haven't been able to find a whole lot about doing the front, but I've heard that you need a union fitting with a 90 degree bend in it to fit through the tight spaces around the front diff. Anybody done it?

I did mine, and what you heard is correct - you need a 90 degree fitting, pointed in the right direction, so the hose will clear the oil pan without kinking severely.

Unfortunately, I have no recollection of where I got the parts. I think it was a bit of a McGyver job, but it's held up well for 3 years.

 

[Ulfr]

IIRC, it's just a normal 1/8" NPT with 90° Angle. I could be wrong on the threading though, it's almost 10 years since I did this the last time. But google seems to verify this.
Note: IF you bother doing a breather mod, do your self a favour and have the hoses long enough to reach into the car. It might save you some headache later if you happen to submerge the car. And it can be a good idea to have some kind of a valve at the end so it won't draw humid from the air.

 

[RonJR]

It's not NPT, it's a British pipe thread. You can force an NPT into it (which is what I think I did), but it's not ideal.

 

[Ulfr]

It's not NPT, it's a British pipe thread. You can force an NPT into it (which is what I think I did), but it's not ideal.

I found few threads that mentioned NPT but I always thought it was BSP, so that might be correct. Somehow I have the feeling I bought 1/8" BSP. But being 10 years... well, memory isn't perfect.
It would also sound logical for it to be BSP since the hydraulics in toyota are BSP if I recall correctly.
Thank you for correcting me.

 

[fwak1234]

When I still had IFS I ran my front straight, no need for a 90* in my opinion since the front diff doesn't move. Just run it over to the passenger side, and up next to the battery with a lawn mower fuel filter for the breather filter. I just used simple 1/4" clear tubing front and rear. Had 0 issues with the front when installed, and rear is doing well still. Will be running almost the same on my 8" front this weekend. Will post a picture of where I stick it in my engine bay. I don't bother running it into the cargo area because if I am in that deep of water then my engine is toast.

 

[a red 4runner]

So I've found out why there aren't many sources on how to elevate the front breather ON '90 TO '95 TRUCKS; '80s 4Runners and pickups have enough space on top of the front diff to fit a 90* angle union fitting WHEREAS, on '90 to '95 4Runners and pickups, a regular union fitting is a tight fit, and a 90* angle union fitting will not fit at all - there's no room for it to turn to thread it! :ybrick:

So, with this in mind, I wondered about maybe trying a 45* angle union fitting! :eyebrows:

I got some coming in the mail. Will report back.

 

[RonJR]

I believe I put mine in while I had the diff out to install my locker.