CLAPET VALVE VENTILATION VAPEUR WILLYS JEEP

Internal combustion engine crankcases need to be ventilated to remove harmful blowby gasses and moisture. This reduces the formation of sludge and acids to help prolong engine life. Many early automobiles used a road draft tube system for crankcase ventilation. Forward motion of the vehicle through the air caused a suction on the road draft tube. This suction circulated air through the engine carrying the contaminated gasses out to the atmosphere. The slow speeds of an off road vehicle do not generate much air flow and therefore less crankcase ventilation. Willys was one of the first manufacturers to use a closed crankcase ventilation system providing a positive flow contained system that does not require vehicle motion for operation. Contaminated gasses are not released to the atmosphere providing another benefit from this system. The following cutaway engine illustration from the service manual, with red highlights added, indicates the air flow.

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