A: The valve cover (aka “rocker arm cover”) gasket is typically made of plastic, rubber, or cork, and is a seal that prevents oil from leaking out of the engine. The oil inside the valve cover is splash oil; it’s not under pressure, but the oil will still leak in a big way if the valve cover gasket is compromised.
With the valve cover gasket removed (sometimes you have to remove the intake manifold first for access), you can see the valve springs and rockers on pushrod (OHV) engines and you’ll see the camshaft(s) on overhead cam (OHC) engines.
Accessing the valve cover gasket can be a long and complicated process. Before everything else, you’ll have to remove everything in the way before you can even get to the gasket. On some vehicles, this includes the PSV hoses, spark plug brackets, and a bunch of other wires.
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