Since the piston rings cannot seal tightly enough, combustible gases penetrate into the crankcase. The mixture of hot oil and fuel vapors can create excess pressure, which has a harmful effect on the crank mechanism. To avoid this, the gases must be sucked out through the engine connecting hose and burned.
Closed ventilation of the engine does not require maintenance.
Functioning
126. Oil separator; 127. Recirculation pipe; 140. Distribution pipe; 141. Pressure regulating valve; a. Ventilation hole diameter 3 mm; A. Blow-off gases; B. Fresh air
The hot gases flow through the oil separator (126) into the cylinder head cover and through the pipe (140) into the suction pipes. In the oil separator (126) the oil is filtered and flows through the recirculation pipe (127) back to the cylinder head.
The pressure regulating valve in the cylinder head cover prevents the vacuum in the engine from becoming too high.
(Material borrowed from an online resource: MercedesMan.ru)
To ventilate the membrane space, a vent hole (arrow) is provided in the cylinder head cover of the pressure regulating valve. It must not be clogged with dirt or preservatives.