Extended Rear Differential Breather

Parts Needed

Toyota Union Fitting- #90404-51319
Toyota Breather Plug- # 90930-03136
Fuel Hose Line (5 to 6 feet; ID 3/8", OD 1/2")
1/4" - 5/8" Hose Clamp (2)

Tools/Supplies Needed

14mm rachet socket
12mm rachet socket
Flat-bladed screwdriver
Xacto knife
Pipe Thread tape
Large Cable Ties (2)

Summary

If you plan on or anticipating off-roading in fairly deep water, extending your rear differential will help you prevent damage to it. The stock rear differential breather plug only extends about an inch above the differential itself. When fording deep water, the cool water has a high probability of being sucked into the differential through the stock plug and as you know, "oil and water don't mix."

The key to this installation is to basically raise the breather plug higher than what you anticipate driving through.

Step 1: Removing the Spare Tire

You'll need some room down there to work so it's best to remove the spare tire. The spare tire is removed by using the supplied tire tool to lower it from its mount. The tire tool is located under the rear seat. After removing it from its plastic clips, insert it into the hole located in the rear cargo area and turn counter clockwise. You will see the tire lowering.

After it is completely lowered, slip the plate out of the tire, roll the tire in a safe location and then pull the tire wire up.

Lift up the passenger seats and you'll see the tire tool.

Place the tire tool in this hole, make the connection and turn counter clockwise to lower the tire.

Step 2: Removing the Rear Differential Breather Plug

As you can see here, the rear differential breather plug is located on the left side of the rear axle.

Remove the breather plug with a long 14mm rachet socket. Be forewarned, it will hiss as the gas pressure escapes from it. I got a bit startled and hit my head. Ok, back to the write up: After removing the plug, tape some thread tape on the new union fitting and use a long 12mm rachet socket to fasten it onto the rear differential.

Rear axle view from the back. The stock plug is shown as (D).

Step 3: Threading the Fuel Line

Here's where I did things a bit differently from others. First, I removed a plug that holds the gas line cover to the body. You really only need remove one single plug (pic below). Wedge some paper in between the body and the gas line cover to allow the fuel line to slip through.

Next, use your Xacto knive and cut an "X" shape in your gas filler gasket. I cut mine on the right side, but in retrospect, it might have been better to cut it a little higher and to the left.

Feed the tube downwards and it should go through the gap. Note: it took me a few tries to successfully thread the tube through so don't give up after the first try. You'll notice that there is enough space for the new fuel line to peacefully co-exist with the existing fuel line. You can now insert the plug back into the gas cover.

View from underneath: (G) is the gas line cover and (P) is the location of the single plug you need to remove. After removing the plug, wedge some paper to create a gap.

Cut an "X" shaped hole in the rubber gasket and feed the tube downwards. If I were to do it again, I'd cut the hole a little higher and to the left.

Here's the differential fuel line coming through the gap you created (G). As you can see, the plug (P) is removed.

Step 4: Connecting the New Fuel Line to the New Union Fitting

Once you've finished threading the fuel line down, run the fuel line as shown across to the right and down to the new union fitting. Leave some slack for suspension articulation.

Next, take your Xacto knife and make sure that the fuel line end is cut straight. Fasten the hose clamp onto the end about a 1/4" from the bottom. Moisten the union fitting w/ a little water or saliva, push the fuel line/pipe clamp onto it and then tighten the hose clamp.

Go back to your gas filler nozzle area and cut the new fuel line tube to length. Now insert a hose clamp to this end of the fuel line and then insert the new breather plug.

You're done! Your fear of deep water can now rest.

Here's the new fuel line (G, marked with yellow) threaded from the gas line cover and running to the new union fitting.