General information
The engine crankcase ventilation system prevents exhaust gases from entering the atmosphere. Fresh air is directed through the air filter via the ventilation hose into the engine crankcase and mixes there with the purge gases. The exhaust gases are sucked in by the intake manifold via the engine crankcase ventilation valve. The engine crankcase ventilation valve lifts the piston depending on the given intake manifold pressure and thus regulates the exhaust gas flow. In other words, at low engine load, the exhaust gases help stabilize the engine, and as the load increases, the flow increases, thereby improving the ventilation capacity.
Figure 6.1. Crankcase ventilation system diagram
Figure 6.2. Location of the crankcase ventilation valve of the 4G1 engine | 
Figure 6.3. Location of the crankcase ventilation valve of the 4G9 engine |
Information copied from the website [MITSUBISHIMAN.ru]