What are the causes of poor crankcase ventilation and blow-by gases?

[Val]

The causes of poor crankcase ventilation and blow-by gases are: 1. The crankcase ventilation check valve is installed backward; 2. The check valve is blocked; 3. The spring force of the check valve fails; 4. Improper installation. The reasons for implementing crankcase ventilation are: 1. To prevent excessive crankcase pressure; 2. To extend the service life of engine oil; 3. To reduce component wear and corrosion; 4. To prevent engine oil leakage. The functions of the crankcase ventilation system are: 1. To prevent engine oil deterioration and reduce wear and corrosion of engine components; 2. To prevent oil leakage from the crankshaft oil seal and crankcase gasket; 3. To re-circulate blow-by gases from the crankcase back into the cylinders for combustion, preventing various oil vapors from polluting the atmosphere.

[DeLouis]

There are several main reasons for poor crankcase ventilation and blow-by. I often drive long distances and find that PCV valve clogging is the most common issue. This component controls engine exhaust emissions, and it can get stuck due to excessive carbon buildup. Additionally, worn or poorly sealed piston rings allow combustion chamber gases to leak into the crankcase, increasing internal pressure. If the ventilation pipes are clogged with sludge, airflow becomes restricted, worsening the problem. I've personally seen cases where engine oil turns black and emits smoke. If not addressed promptly, fuel consumption spikes, the engine overheats, and even oil seals can burn out. Prevention is simple: regularly clean the PCV valve, inspect piston rings and pipes, and avoid extending maintenance intervals too long. Also, in winter, fluids thicken, making ventilation systems more prone to failure. Pay extra attention in cold weather to avoid sudden breakdowns while driving.

[AlexanderAnn]

Problems with crankcase ventilation usually occur due to a failed or clogged PCV valve, which controls airflow and can get stuck when dirty or aged. Poor piston ring sealing is another major cause, allowing gases to leak from the combustion chamber into the crankcase, creating excessive pressure. Carbon buildup or sludge clogging the ventilation system's filters and pipes can also restrict airflow. From my own repair experience, high-mileage engines are particularly prone to this issue, with oil getting dirty quickly and noticeably higher fuel consumption. If left unrepaired, it can cause severe engine wear and even oil leaks that pollute the environment. Regularly listen for unusual engine noises while driving and address them promptly. Poor ventilation also affects emissions, potentially causing vehicles to fail emission tests.

[SanVera]

I've repaired many cars, and there are usually three main reasons for poor crankcase ventilation. The PCV valve is clogged or broken, unable to control the airflow. Worn piston rings cause gas leakage, allowing gas to enter the crankcase and increase pressure. Blockages in the ventilation system pipes or filters hinder smooth exhaust. These issues can lead to rapid oil deterioration and reduced engine efficiency. Checking these components during maintenance ensures peace of mind and safety.