FACTS YOU SHOULD KNOW ABOUT
ENGINE CRANKCASE BREATHERS

All engine crankcases breathe. Most of the air comes from piston ring and worn valve guide by-pass. In a healthy engine crankcase pressure is a minuscule 1" to 3" of H₂O, about the same as your lungs generate at rest. Above 4", excess oil by-pass makes engine performance unsatisfactory. Correcting this condition and, also, preventing liquid water from entering the separator are necessary before installation. (Liquid water is a cold weather problem with airplanes having long, uninsulated breather lines exposed to ram air, whether or not they have separators).

The breather is a crankcase opening to atmosphere for venting normal air pressure. The air being vented carries oil mist and water vapor. M-20 Air/Oil Separators are highly engineered devices which agglomerate the oil mist but by-pass the water vapor and air to the atmosphere. Liquid oil is returned to the crankcase leaving the aircraft belly clean. The oil that is saved is normally far more oil than is burned in the cylinders. These separators are intolerant of faulty installation. Please contact us for help if performance falls short of expectations.

~ Bill Sandman ~

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