Almost any car engine has a valve cover that covers the valve train components at the top of the engine. The valve cover gasket seals the gap between the valve cover and the cylinder head. In modern cars, the valve cover gasket is made of rubber material. Over time and under higher temperatures, the gasket becomes dry and brittle and may start to leak. How often should it be replaced? What are the symptoms of a bad valve cover gasket? There is no maintenance requirements for valve cover gasket replacement. It only needs to be replaced if it leaks.
Symptoms of a leaking valve cover gasket include oil drops under the engine, burnt oil smell under the hood and visible traces of oil coming down the engine. Of course, a valve cover gasket is not the only source of possible oil leaks. There are many other engine components that can also leak oil, including cam and crank seals, front engine cover seal, PCV system, oil pressure switch and other parts. To repair an engine oil leak, the source(s) of the leak must be identified first.
How is a leaking valve cover gasket diagnosed? If the valve cover gasket is suspected leaking, your mechanic may recommend cleaning the affected area and check it in a few days to see where the fresh leak is coming from. Sometimes, oil leaks from a valve cover gasket are clearly visible. For example, see this photo. You can see that oil is seeping out from under the valve cover. In some cases, a leaking valve cover gasket or O-ring may result in oil getting into the spark plug well. This issue is often discovered during spark plug replacement. O-rings that seal spark plug wells are usually included in the valve cover gasket kit.
How expensive is the valve cover gasket replacement? In a simple in-line 4-cylinder engine, the valve cover gasket replacement may cost $16-$65 parts and $55-$110 labor. In a Subaru flat "boxer" engine with two separate valve covers, your mechanic may charge $25-$85 for parts and $120-$280 for labor.