Rocker cover

The valve cover, also called cylinder head cover, is the chief conclusion of a (standing upright ) four-stroke internal combustion engine.

It holds the upper actuation elements of the valve drive and prevents the leakage of the lubricating oil into the environment, as well as the ingress of air into the engine: modern engines are controlled a slight negative pressure in the interior, to prevent combustion gases or vapors from the engine into the environment reach. The valve cover very often also contains the filling hole for the engine oil along with the toggle clasp cover, see pictures of a TDI engine.

If the valve train is equipped with an overhead camshaft and it is driven by a chain (all engines from Daimler -Benz, many engines from BMW, some engines from Audi, etc.), the valve cover also includes the camshaft sprockets.

The valve cover is often sealed against the cylinder head with a U-shaped plastic seal, called the valve cover gasket. For decades, the valve cover was sealed with a circumferential cork or compressed material seal, as also in the two valve covers on a VW Beetle engine ( see picture). Now, however, almost exclusively rubber or plastic seals used. Replacing them with a plastic seal is easily possible with most older engines.

With advanced running performance valve cover gaskets are often leaky and must be replaced, as the motor oil can get into the environment and onto hot engine parts otherwise. Dropping engine oil to parts of the operating temperature, exhaust system, there is even a fire in extreme cases.

Many very old engines valve cover is missing. Then the valve train of the engine is running freely and openly visible; you can see the valve springs etc. " at work ". The possibly leaving here lubricating oil has access to the environment.

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Valve cover a Honda CB 450 S year 1987; a camshaft ( SOHC) is mitüberdeckt

Valve cover a Honda CB 750 Four F2 Super Sport Year 1978 ( OHC ) with valve lash adjustment holes

Valve cover on a VW Beetle in year 1975 with wire spring clip