Differential Breather, but what about transfer case

XeRoland

New member
I am seeing a lot of videos on installing the breather kit on the rear differential. But I also heard that other parts of the drive train (transfer case and transmission) can be hooked up to the breather kit. Should all these components be attached to the manifold? There seems to be emphasis on the rear differential, but what about the front of the driveline?
 

Joe917

Explorer
Don't join them into a manifold. run the breather lines individually higher than anticipated fording depth. The problem usually is entering cold water with hot diffs, the sudden cooling causes the diff to suck air, and if no breather line, water. Put a line on everything with a breather.
 
  • Like
Reactions: bkg

DaveInDenver

Expedition Leader
From the factory 2003+ 4Runner, 2005+ Tacoma and 2006+ FJ Cruiser have an extended breather for the front diff and transmission. They are located in the engine bay near the battery. So are you talking about using that "manifold"? It's not really a manifold but just two breathers joined.

FWIW, why do you think you need to extend the breather on the rear axle? Not saying you don't but the little breather on your axles is already designed to be a one-way valve to burp pressure and stay closed when the diff gets dunked in cold water. It works OK for occasional use. But the chance does exist for the spring to get weak or it to clog and not work. I replaced them after about 15 years on my 1991 (which had none extended from the factory) but the ones on my 2008 still seem to be working. I eventually extended the diff breathers on the 1991 using sintered metal pneumatic filters.

Extending the line comes with some things to watch, a kink in the hose can over pressurize the axle and force gear oil past the rear axle seals into your drums. It getting cut or pulled off will let dirt in unabated. I think that's why Toyota didn't put them on the rear axles, routing the hose and preventing it from being snagged was more effort than it was worth. The front diff and transmission (and t-case) don't move much, unlike the rear which twists around being a live axle.

Also you'll see the breather run up the fuel tank filler hose and into the space behind the gas cap door. People have found, at least on Tacomas, the breather eventually stops working. Whether that is due to fuel vapors or being bumped, not sure. But running it into the bed of the truck is actually preferred if you use the spring-loaded ones from Toyota.
 
Last edited:

lugueto

Adventurer
The problem usually is entering cold water with hot diffs, the sudden cooling causes the diff to suck air, and if no breather line, water.
This is the most common case water floods a differential, believe it or not. And it will happen with extended breathers if you don't change your breather's check valve with a free intake of some sort. I use an brass pneumatic breathers and the end of my lines. ARB uses their compressor filter, for example.

To answer the OP's question:

It is advisable to raise everything with a breather, but the most vulnerable parts are the differentials because they're the lowest ones. We cross deep water very frequently and where everyone has raised diff breathers, not all have raised transfer and transmission breathers. They've never really had a problem unless they're stuck in it for extended periods of time, where even the engine gets filled with water anyway.

The emphasis on the rear differential is because the breather is on the diff itself, whereas the front diff has a raised breather that's usually on the driver's side fender in most Toyotas. The reasoning behind the front diff being raised from factory is because this is the most vulnerable one by far, so they raise it beforehand.
 

OmegaMan73

Observer
Take a look here. This has everything you want in a breather kit. I run this kit for all of my breathers and I'm happy with it. Customer service is top notch and Erick will answer any questions you have.
 
On my 2003 Tundra, the front diff breather is already run pretty high up. It mounts to the frame on the driver side. I doubt you would forge water that deep. I know I wouldn't.
 

wmg

New member
I have done all 4 of mine with parts outa the junk box mostly...way cheaper then those kits....also I use a breather filter rather then the tin OEM check valves
 

Attachments

Last edited:
Quoting your comment about 2006+ FJ Cruisers having the extended breathers for front diff and transmission, do you know if this applies to the Lexus GX470 also?

From the factory 2003+ 4Runner, 2005+ Tacoma and 2006+ FJ Cruiser have an extended breather for the front diff and transmission. They are located in the engine bay near the battery. So are you talking about using that "manifold"? It's not really a manifold but just two breathers joined.

FWIW, why do you think you need to extend the breather on the rear axle? Not saying you don't but the little breather on your axles is already designed to be a one-way valve to burp pressure and stay closed when the diff gets dunked in cold water. It works OK for occasional use. But the chance does exist for the spring to get weak or it to clog and not work. I replaced them after about 15 years on my 1991 (which had none extended from the factory) but the ones on my 2008 still seem to be working. I eventually extended the diff breathers on the 1991 using sintered metal pneumatic filters.

Extending the line comes with some things to watch, a kink in the hose can over pressurize the axle and force gear oil past the rear axle seals into your drums. It getting cut or pulled off will let dirt in unabated. I think that's why Toyota didn't put them on the rear axles, routing the hose and preventing it from being snagged was more effort than it was worth. The front diff and transmission (and t-case) don't move much, unlike the rear which twists around being a live axle.

Also you'll see the breather run up the fuel tank filler hose and into the space behind the gas cap door. People have found, at least on Tacomas, the breather eventually stops working. Whether that is due to fuel vapors or being bumped, not sure. But running it into the bed of the truck is actually preferred if you use the spring-loaded ones from Toyota.
 
Top