Should the valve cover be replaced for oil leakage?

After the valve cover gasket leaks oil, you will see many traces of oil near the side of the top of the engine. This is mainly caused by two reasons.

One is that the valve cover gasket is really aging and fragile, losing its sealing ability, leading to oil leakage. This situation is actually good. Just open the bonnet and replace the gasket.

The second type is that the PCV valve of crankcase ventilation system is blocked, which leads to excessive pressure in the engine and eventually leads to oil leakage under pressure. If this problem is not found out, it will cause more trouble in the future, such as oil leakage of crankshaft oil seal and so on. However, it is very simple to judge whether the PCV valve works normally: when idling, the working state of the PCV valve can be judged instantly by detecting the vacuum degree of the crankcase air inlet with your fingers.