Patrol 4×4 – Nissan Patrol Forum

Diff Breathers When a hot axle hits cold water it cools rapidly. This has the effect of lowering the air pressure inside the axle and the diff housing, causing air to be drawn in via the diff breathers. Extending your diff breathers higher up the chassis (standard on most Landcruisers) with the aid of plastic tubing is a “must do” for regular water goers. The 4x4 pictured has run both front and rear breathers to a high position on the firewall under the bonnet. However, it is no guarantee that water will not enter your diff. The sudden reduction in air pressure inside your diff can still cause water to be drawn in via your axle seals if the diff breathers do not equalize the pressure quick enough. This is why its still necessary to allow the 4x4 time to cool down, even when extended diff breathers are fitted.