What Is A Valve Cover Gasket And Why Is Yours Leaking?

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What Is A Valve Cover Gasket And Why Is Yours Leaking?

22 May 2019
 Categories: , Blog

Springing leaks is one thing that cars seem to be particularly good at. Your car has a number of important fluids which are kept in place using a variety of gaskets, hoses, and o-rings, and as your car ages any or all of these fluids can begin to slowly (or not so slowly) make their way into the outside world. Not only are leaks bad for the environment, they will also affect your car's operation. Valve cover gasket leaks are one particularly common type of oil leak found in many makes and models, and they can strike cars that may only be a few years old or that have less than 50,000 miles on them.

What is a Valve Cover?

Your valve cover is a panel that seals to the top of your engine. Depending on your particular car, this cover may be made of metal or a composite plastic. The valve cover itself serves the vital role of keeping dirt, water, and other contaminants out of your engine's internal parts. Without the valve cover, your engine would almost certainly pick up debris and fail catastrophically in short order. Luckily, even valve covers which are prone to failure do not fail in such a way that they allow this type of damage to occur. Valve cover failures usually manifest as minor oil leaks which can become more serious over time.

What is a Valve Cover Gasket?

Since part of your valve cover's job is to contain the oil lubricating your internal engine parts, it must be sealed to the engine with a gasket. As with the cover itself, the gasket material used will vary depending on the make and model of your car. Often, this gasket is constructed from a rubber compound. Over time and exposure to multiple heating and cooling cycles, rubber gaskets have a tendency to plasticize. This process causes the gasket to become hard and brittle, and ultimately it will lose its ability to properly seal the cover.

What are the Symptoms of a Valve Cover Gasket Failure?

The real-world symptoms of a valve cover gasket failure can range from subtle to extreme, depending on how bad the failure is and how long it has been left unaddressed. Minor leaks usually go unnoticed, and in many cases not enough oil is lost to be noticeable between oil changes. Early symptoms may be a burning smell from the engine bay, as oil from valve cover gaskets will often drip onto the hot exhaust manifold where it then burns off. As the leak progresses, there will eventually be a noticeable loss of oil.

Your valve cover gasket is also part of your engine's vacuum system. If a leak is serious enough, you may begin to lose vacuum through the gasket or through damage to the valve cover itself. In this case, you will experience symptoms similar to any other vacuum leak. These symptoms may include various drivability issues such as a loss of power or rough, inconsistent idle.

While oil leaks should never be ignored, valve cover gasket failures are relatively minor. For most cars, repairing this type of leak should only cost a few hundred dollars and, as long as the car is not allowed to run too low on oil, the leak itself is unlikely to cause additional damage. Talk to an auto repair service for more help.