What is the function of crankcase ventilation?

The function of crankcase ventilation is primarily to allow pressure that builds up in the crankcase to escape. During the operation of an engine, combustion gases can blow by the piston rings and enter the crankcase, creating increased pressure. If this pressure is not managed, it could lead to oil leaks or even seal damage.

Crankcase ventilation systems are designed to provide a controlled pathway for these gases and pressure to be expelled, which helps maintain optimal operating conditions within the engine. This system also contributes to better engine efficiency and reduced emissions by directing the expelled gases back into the intake system to be burned again, rather than releasing them directly into the atmosphere.

The other options, while related to engine operation, do not accurately describe the primary purpose of crankcase ventilation. For instance, cooling oil or increasing oil flow pertains more to function than pressure management, and filtering air impurities is a role fulfilled by air filter systems, not the crankcase ventilation setup.