Diff Breather Kit: Protect Your Diffs, Gearbox and Transfer Case on Every Water Crossing

A diff breather kit stops your differentials, gearbox and transfer case from sucking in water when you drive through river crossings and other large water hazards. That one small upgrade can save you from serious and expensive repairs.

Why water gets into your differentials

Your differentials, gearbox and transfer case heat up during normal driving, and the air inside them expands. Most of these components come standard with one-way valve breathers that let the extra pressure escape. Here is where that goes wrong in water:

1. The casings heat up

   Normal driving warms the air inside, which builds pressure in the casings. The standard one-way breather valves let that pressure out.

2. Cold water hits hot metal

   When you enter a river crossing or large water hazard, the cold water cools the expanded casings quickly, and they contract.

3. A vacuum forms

   The contraction creates a vacuum on the breather valves. A one-way valve will not let air back in, so the casing pulls from somewhere else.

4. Water comes in through the seals

   Water is often sucked in past the surrounding oil seals, into your casings, axles and differentials.

How a breather kit fixes it

The kit is built around a hub that carries air in and out of your differentials, gearbox and transfer case. It includes a length of air tubing, which you run to a high point, usually under the bonnet. That is the spot best protected from dust and water when the components draw air back in as they cool.

Because air can now flow both ways through a protected, elevated point, the vacuum has no reason to pull water through your seals.

The 4 port ARB Diff Breather Kit

Out of the box, the 4 port ARB Diff Breather Kit connects to all four key components. It comes with enough tubing and fixtures for the most common setup, which is two differentials.

• Front differentialTubing and fixtures included
• Rear differentialTubing and fixtures included
• Transfer caseNeeds a small amount of extra tubing and fixtures
• GearboxNeeds a small amount of extra tubing and fixtures

Extra tubing and fixtures are sold separately.