When does the valve cover gasket need to be replaced?

The valve cover covers valve train components at the cylinder head of the engine, see this photo. The valve cover gasket seals the gap between the valve cover and the cylinder head.

In most modern cars, the valve cover gasket is made of rubber. Over time and under high temperatures, the gasket hardens and becomes brittle, which might cause it to leak oil.

When does the valve cover gasket need to be replaced? There are no mileage requirements, the valve cover gasket only needs to be replaced if it leaks. If the valve cover gasket is old, it's also often replaced during major engine repairs.

What are the symptoms of a bad valve cover gasket?

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. See the photo below.

Of course, the 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 of the leak must be identified first.

How do mechanics diagnose a leaking valve cover gasket?

If the engine shows oil leaks, but the source of the leak is not clear, your mechanic may recommend cleaning the affected area and re-checking 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 the spark plug replacement. O-rings that seal spark plug wells are usually included in the valve cover gasket kit. A valve cover gasket kit (part) cost $20-$65.

How much does the valve cover gasket replacement cost?

In a simple in-line 4-cylinder engine, the valve cover gasket replacement may cost from 1.0 to 1.5 hours of labor plus the cost of the gasket kit which is not very expensive.

In a Subaru "boxer" engine with two separate valve covers it's a bit more expensive. For example in the 2012+ Subaru Forester with a non-turbo engine, replacing a valve cover gasket in a repair shop will cost 1.3-1.5 hours of labor plus the cost of part for one side. Valve cover gaskets are very common to leak in many Subaru engines.

Replacing valve cover gaskets in a V6 or V8 engine involves more labor. For example, in the 2012-plus Ford Edge, the intake manifold needs to be removed to gain access to the rear valve cover bringing the labor cost to 3.1-3.5 hours to replace valve cover gaskets on both banks of the V6 engine.

Should the valve cover gasket be replaced as part of a tune-up?

It's not necessary to replace the valve cover gasket if it's not leaking. If it show signs of leaking and your spark plugs are due for replacement soon, it does make sense to combine both services, as a large portion of labor overlaps.

For example, for the 2012 V6 Ford Edge we mentioned above, replacing all 6 spark plugs together with both valve cover gaskets will add the cost of spark plugs and a small amount of extra labor.

How easy is it to replace valve cover gasket DIY? If it's a simple 4-cylinder engine, with proper tools and necessary skills, it's a "3" job on the difficulty scale from 1 (easy) to 10 (leave it to pros).

The valve cover gasket is sold as a kit and can be ordered from a dealer, online, or purchased from a local parts store. You may also need a special sealant. Mechanics use sealant to seal tight spots and corners of the valve cover gaskets.

What will happen if you continue driving with a leaking valve cover gasket?

It all depends on how bad the leak is. Many high-mileage cars have some "sweating" around the valve cover area which is normal. If the engine is not losing oil, there is no oil drops on the parking spot and there is no burnt oil smell under the hood, it's not a big problem.

If there is a noticeable leak, your engine is losing oil that may also damage the asphalt on your driveway. If you can smell burnt oil from under the hood while driving, it means the oil vapors are in the air you breathe, which is not very good for your health. We have also seen cases where oil leaking from the valve cover gasket has damaged the drive belt. See this photo from the post about a drive belt.