So your differential has oil in it. Oil expands when it gets warm. Without a breather, the pressure would rise in your differential and might shorten the life of various oil seals. The stock breather is right on the differential. In the event that you should splash through a puddle that is deep enough to immerse the breather, there is a chance that your differential might suck some of that water in.

Water and oil don't mix very well and the resulting milkshake certainly doesn't lubricate very well. In the end, you have three options: (1) Stay out of the water; (2) Flush your differential every time it might have gotten wet; (3) Extend the breather. Well, here's the procedure for option three.

The front differential already has an extended breather on it, coming up into the engine compartment. Some folks add a couple of feet onto it, but it's high enough to handle most moderate off road travel.

Parts/Materials Needed:

• 8 feet of 1/4 rubber fuel line
• 2 small hose clamps
• A few nylon zip ties
• 1 Union (Toyota part number 90404-51026), should be less than $5

Some dealers may claim that they can't find that part number in their systems. Try requesting the part number without the dash (9040451026 or 90404 51026).

Tools Needed:

• Box/Open wrenches, 10mm and 14mm
• Screwdrivers
• Wire Cutters
• 1 cup boiling water

Estimated Time: less than 1 Hour

Procedure:

Here's a photo showing the location of the stock breather on the differential housing.

Close-up of stock breather

Use a 14mm wrench to remove the stock breather. Use a rag to clean around the breather before you remove it completely.

Use a 10mm wrench to thread the Union (90404-51026) into the differential housing. It will tighten down until about one thread is exposed.

Dip one end of your rubber hose in a cup of boiling water for 30 seconds, then insert the stock breather threads into the hose. You want to get all of the threads into the tubing. This will allow your diff to continue to breath as it would in a stock configuration and will cut down on the chances of dust or moisture getting sucked in. Secure the breather with one of the hose clamps. Some folks use a VW type fuel filter on the ends of their breathers.

There are a variety of places you can vent to. Some choose to run a hose all the way up to the engine compartment. We followed the electric locker cable/brake lines up by the fuel filler neck. This view is from the perspective of the left, rear tire, looking up into the bed rail. The stock breather end of the hose was secured with wire-ties so that it was above the fuel neck. The hose was routed along the fuel filler neck, over the frame and along the locker cable.

Once the hose was routed down near the differential, we left a bend in the hose so that it would not be pulled tight when the suspension flexes. Once we had the hose secured, we cut off the excess and fitted the hose over the Union. Secure the hose with the remaining hose clamp.