The intake and exhaust valves are primarily cooled by the valve seats. When the valves close, they make contact with the valve seats, which are part of the cylinder head. This contact area plays a crucial role in dissipating heat away from the valves. As the engine operates, combustion generates significant heat in the combustion chamber, and the valve seats help absorb and transfer this heat away to the cylinder head, which is then dissipated to the engine cooling system.
The thermal conductivity of the materials used for the valve seats, along with their design, is optimized to enhance the cooling process. Maintaining proper temperatures for the valves is vital for preventing overheating and ensuring their longevity and proper function. This cooling method is particularly important for exhaust valves, which face higher temperatures and pressures due to the combustion process.
Other components like the valve guides and lifters do play roles in the operation of the valves, such as guiding their movement and maintaining alignment, but the primary mechanism for cooling the valves is through the contact with the valve seats.