The valve cover on an engine is the metal part that is bolted to the top of the valve train. As oil is circulated through the engine, it lubricates the valve train under the valve cover. A valve cover is designed to be removed to allow access to the mechanical components underneath the cover. The gaskets that seal the cover (or covers) to the engine are a common source of oil leaks. A leaking valve cover gasket can create an oily mess in the engine bay and cause the engine to smoke as the oil leaks out and burns off on the engine. Troubleshoot your valve cover to pinpoint the problem.
Open the hood and shut off the engine. Inspect around the valve cover. A leaking cover will usually seep around the edges of the cover where it mates to the engine. However, just because there is oil around the valve cover does not necessarily mean that the leak is originating there.
Steam clean or wash the engine. If the engine is very dirty, it will make it difficult to pinpoint the exact source of the leak. By thoroughly washing the engine, fresh oil will be far easier to see. Use a steam cleaner to wash the engine. You can also use degreaser and a wire brush to scrub around the valve covers, paying close attention to the edges of the cover. Dry it with clean rags.
Drive the vehicle to bring the engine up to operating temperature. This will send fresh oil to any leaking gaskets and allow you to see the source of the oil. Carefully inspect the engine while it is still running. Look around the edges of the valve cover as well as the bolts that hold the cover in place. These bolts often have rubber washers that can leak oil.
Replace the valve cover gasket if you discover a leak.
