Air On Board 4 Port Diff Breather Kit Universal

Air On BoardSKU: SQ3839342

Sale price $74.89
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Product Info

A differential/axle breather serves the important purpose on a 4WD vehicle of venting the air pressure in drivetrain assemblies such as the differentials, transmission, and transfer case. Under normal operations, these assemblies heat up and the air inside expands, increasing the pressure, and thus the need to be vented to the atmosphere is created. If a factory-fitted breather gets blocked or jammed shut this pressure build-up can cause the oil seals to blow out. When the drivetrain assembly cools down the air inside contracts and creates a vacuum.

Many drivetrain assemblies are fitted with a breather from the factory. These factory breathers are usually a one-way valve mounted directly to the housing or remotely on a short tube. The shortfall with the factory breathers is that driving through water crossings creates a vacuum caused by the drivetrain assembly being cooled rapidly by the water. This vacuum will tightly close the valve shut causing air to be instantly drawn into the assembly through the seals. Many times the seals are still submerged below water, leading to the water being drawn into the drivetrain. This will contaminate the oil and possibly damage drivetrain components or your Air Locker.

The AOB Differential Breather Kit is designed to eliminate these shortcomings by providing a high flow, zero back pressure, and zero vacuum breather system. This is achieved with 4 high-flow SINTERED air filters fitted in a central bracket that will allow up to four drivetrain assemblies to be vented to one central location, ideally somewhere on the vehicle that will be above the water level at all times. This kit is intended to replace your factory breathers and contains enough fittings and tubing to connect at least four drivetrain assemblies.


  • Increase the life of your differential/ axle, and Transfer case assemblies 
  • High flow, zero back pressure, zero vacuum breather system
  • 4 high-flow SINTERED air filters for each breather line
  • A  small investment could save you hundreds of dollars


  • (1) 4 stainless steel mount plate
  • (2) 1/8 BSP M to 1/4 PU
  • (2) 1/8 BSP M to 1/4 PU 90 degree
  • (4) 1/8 BSP F to 1/4 PU bulkhead
  • (4) 1/8 BSP filter
  • (1) 40-foot 1/4 PU hose
  • (15) cable ties
  • (3) self-tapping screws

Note: This item will require modification to adapt transmission breather fitting.


Universal Fitment

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