Rocker covers seal the valve train assembly, preventing oil and combustion gas leakage. Positioned atop the cylinder head, they enclose the rocker arms, pushrods, and valve springs. Typically constructed from aluminum or plastic, they feature integrated baffles to manage oil return and reduce oil aeration. Gaskets or O-rings provide a static seal between the cover and cylinder head, maintaining compression and preventing contamination. Modern designs often incorporate PCV valve mounting provisions for emissions control and crankcase ventilation.