As a vehicle’s engine operates, the intake and exhaust valves open and close rapidly while the pistons move up and down in the cylinder. These mechanical actions require a constant supply of hot oil to lubricate the moving parts.
The valve cover gasket helps to prevent oil from escaping the engine by providing a tight seal between the engine and valve cover, typically made of rubber, plastic, or cork. As a result, the valve cover gasket is one of the engine’s critical components.
However, like other engine components, the valve cover gasket will wear out over time and may no longer be able to contain the engine oil effectively. A worn or leaking valve cover gasket can cause oil to escape and allow debris and small particles to enter the space between the pistons and cylinder, resulting in friction and increased wear and tear.
The escaping oil also means that the engine components will receive less lubrication and may begin to grind against each other, putting more stress on the engine and shortening its lifespan. It is important to be aware of the signs of a leaking valve cover gasket and to have it replaced promptly.
Symptoms of A Leaking Valve Cover Gasket
A bad valve cover gasket has multiple different symptoms, some that are similar to other issues with your engine and some that are unique to the specific gasket. Some of the symptoms that can be signs of a bad gasket include:
#1. Visible Oil Leaks.
When oil is able to escape, it’ll often leak onto different parts of the engine that may be visible when you pop your hood. Other times, it can drip all the way to the ground and you’ll be left with a blackish brown stain on your driveway under the engine bay.
Keep an eye out for these leaks, as having an engine soaked in oil is a good indicator that something isn’t right.
#2. Low Engine Oil.
With an oil leak comes the accompanying low oil light. If you have an oil light illuminated on your dash or suspect low oil, shut off your car and check your dipstick, as running with low oil can be harmful for your engine even in short periods of time.
If you know you have low oil, top off your engine immediately and bring your car to an expert
#3. Smell of Burning Oil.
Often when oil is leaking from the valve cover, it can drip onto extremely hot parts in your engine such as the exhaust pipes or engine block.
If you smell burning oil it means your engine is losing oil, and may have or will soon reach dangerously low levels. If you smell this distinct smell, make sure to take it into a service shop to locate and fix the source of the leak.
#4. Misfires.
With a bad gasket, the oil is able to leak into the spark plug wells and eventually soak the spark plugs. This can result in your engine misfiring, which is the failure of a cylinder to ignite during the engine’s cycle. Misfires will result in reduced performance, and the spark plugs will need to be replaced. In serious cases, misfires can even lead to engine fires.
It’s important to look for misfire codes on your dash, and take your car in for service as soon as you see one. In severe instances, you might see your check engine light blinking repeatedly. You should pull over immediately and have your car towed to a professional, as driving with a severe misfire can cause extremely expensive damage to your catalytic converters.
How to replace a valve cover gasket?
Step 1: The first step may be the last step. Before tearing everything apart, first try gently cinching down the valve cover bolts or use a torque wrench. Over-tightening bolts will not stop bad gaskets from leaking. Aluminum valve covers can crack. Steel valve covers can warp. Monitor oil level after tightening. Move on to step two if oil is still leaking.
Step 2: Allow the engine to cool. Consult the service manual or instructions for valve cover removal. This car is turbocharged and had a fair amount of plumbing in the way. Remove throttle cables, spark plug brackets, PCV hoses and anything else in the way. Remove the valve cover bolts.
Step 3: Lift off the valve cover. Tapping with a rubber mallet can help loosen the valve cover’s grip. Be extremely careful not to drop anything into the engine. If a nut or bolt falls into the engine there will be a lot more work to do. Even an old newspaper tented over the engine can help stop this from happening.
Step 4: Remove the old valve cover gasket and install the new one. The valve cover shown here is cast aluminum and has a groove in which the gasket sits. If scraping is required, do not use metal scrapers on aluminum valve covers or cylinder heads. Use plastic to prevent leak-causing nicks. Also note the new grommets on valve cover bolts.
Step 5: Apply silicone only where required. Do not use silicone or sealer unless the service manual or gasket instructions say to use it. Clean all oil off all surfaces before applying silicone. Allow silicone to cure before starting engine.
Step 6: Install the valve cover with the new gasket and tighten bolts to the recommended torque. Valve cover bolts don’t require too much twist. A torque wrench and service manual will eliminate guesswork. Install everything you removed to get at the valve cover.
Summary
The valve cover gasket is placed between the engine and the valve cover to keep the oil inside the engine body. A worn-out gasket can allow oil to leak into other parts of the engine, causing performance issues.
Replacing the gasket is relatively inexpensive and a straightforward process, but it is always best to have a professional mechanic handle the job if you are unfamiliar with engine-related tasks.