or rocker boxes are covers that are put over the rocker arms in a combustion engine. Their main purpose is to keep dirt away from the rocker arms
whilst keeping the oil in.
The first combustion engines in cars didn’t have rocker boxes resulting in the intake and exhaust valves constantly needing to be oiled. Thanks to the installation of a rocker cover
this is no longer necessary.
The rocker cover gasket
in turn seals the joint between the rocker box and the engine. If the rocker cover gasket no longer seals properly, you might find oil leaking from your engine.