What Causes Oil Leakage from the Valve Cover Gasket?
2 Answers
Oil leakage from the valve cover gasket may be caused by corrosion and aging of the seal. The leaked oil flows into the spark plug, which is why there is oil in the spark plug as well. The solution is to replace it with a new gasket. Continuing to use the aged gasket may lead to major malfunctions. The valve cover gasket is primarily used to seal and prevent oil leakage. The material of the valve cover gasket is mostly rubber, which can harden and age over time, resulting in oil leakage. In the structure of an automobile engine, the end of the valve is connected to the camshaft via a tappet or pushrod, and the camshaft controls the movement of the valve. In modern engines, the camshaft is often positioned at the top of the cylinder head, so the valve chamber is also the camshaft chamber. Above the valve chamber is the camshaft cover, which, together with the cylinder head, forms a nearly enclosed cavity. There are also oil return passages, oil supply passages, and other oil circuits connecting to other chambers.
My old car also had an oil leak last year. The mechanic said it was due to the aging and deformation of the valve cover gasket. Over time, the rubber hardens and cracks. Another time, improper installation during maintenance was the issue—the screws weren’t tightened in the correct sequence, resulting in insufficient compression and oil seepage. High temperatures are also a problem; when the engine overheats, the gasket contracts faster, especially during long trips, making leaks more likely. Now, I use higher-viscosity oil to slow down corrosion and check for oil stains under the hood every month. If I spot any leakage, I replace the gasket immediately, as oil dripping onto the exhaust pipe can cause smoke or even a fire in severe cases.
