Extended diff breather install
I finally decided to use the parts hat have been sitting on my workbench for the last three months and extend the rear diff breather up to the gas filler cap.
What is it and why:
The stock rear differential breather on the 4runner stubs out at the top of the axle housing, for daily driving this isn’t an issue but when crossing deep water this breather “plug” can become submerged. When this happens the rapid change in temperature causes a vacuum in the axle housing that can either suck water through the one way breather plug or the wheel bearing seals. By extending the breather plug up and replacing it with a different style of breather the axle is allowed to both “inhale” and “exhale” through the plug rather than just exhale, preventing the entry of water through the wheel bearing seals.
Parts needed and cost:
Toyota union P/N 90404-51319
Toyota Plug, Breather P/N 90930-03136
6 feet of 3/8in fuel line
8 inches of 5/8in heater hose (this is optional but I used it to insulate the breather line from rubbing)
Zip ties
Teflon tape
2 3/8in hose clamps
The two Toyota parts cost me about 17$ at the dealer and the 3/8 fuel line was 10$ at autozone. I had the rest of the things laying around from other projects. Total cost should be around 30$
Basic Procedure:
I followed this write-up so refer to
this for more detail.
The basic things that need to be done are, remove the stock breather and replace it with the Union (I also wrapped the union threads with Teflon tape to provide a better seal), route the fuel line up to the gas cap and through the gasket, install the breather plug and your done.
In the write-up I linked they remove one of the clips securing a plastic shroud, I found that this isn’t needed and you can just run the fuel line next to the other pipes by pulling it up with a piece of wire.
Another little side note is make sure that you leave enough slack in the fuel line to allow for your axle to droop.
Pictures:
Connection at diff
IMAG0325 by
Phoenix Black, on Flickr
Hose routing
IMAG0327 by
Phoenix Black, on Flickr
Connection at gas cap
IMAG0327 by
Phoenix Black, on Flickr