What is the primary function of a crankcase breather system?

The primary function of a crankcase breather system is to allow positive pressures to exit the crankcase and maintain vacuum. This is essential for optimal engine operation. As the engine runs, particularly during periods of high RPM and power generation, the combustion process creates pressure within the crankcase due to blow-by gases – these are gases that escape past the piston rings into the crankcase.

If this pressure is not ventilated, it can lead to numerous issues, including oil leaks, increased oil consumption, and difficulty in the proper movement of engine components due to decreased pressure. The breather system allows these excess gases to escape while ensuring that a slight vacuum can be maintained, which is beneficial for engine efficiency and longevity.

The mechanism often includes a breather valve and may redirect the gases back into the intake system to be burned, which helps in reducing emissions and ensuring that the engine runs smoothly. This function is crucial in maintaining a controlled atmosphere inside the crankcase, supporting the overall health and performance of the engine.