Typically a cylinder head gasket is exposed from a vacuum to 1000 psi.

Typically a cylinder head gasket is exposed from a vacuum to 1000 psi.

• A. False
• B. Only under vacuum
• C. True
• D. Only under 200 psi

Answer: (C)

A cylinder head gasket must seal across a very wide range of pressures during an engine cycle. On the intake stroke, the manifold can create vacuum on the cylinder head side, pulling pressure down toward near zero absolute pressure. Then, as the piston compresses the charge and the spark plug ignites, the combustion chamber pressure spikes to very high values—often around 1000 psi or more in many engines. The gasket sits between the cylinder head and the engine block while this pressure swings from a low (vacuum) on one side to a high positive pressure inside the cylinder on the other, so it must be designed to withstand these large differential pressures. That’s why the statement that the gasket is exposed from a vacuum to about 1000 psi is true.

A cylinder head gasket must seal across a very wide range of pressures during an engine cycle. On the intake stroke, the manifold can create vacuum on the cylinder head side, pulling pressure down toward near zero absolute pressure. Then, as the piston compresses the charge and the spark plug ignites, the combustion chamber pressure spikes to very high values—often around 1000 psi or more in many engines. The gasket sits between the cylinder head and the engine block while this pressure swings from a low (vacuum) on one side to a high positive pressure inside the cylinder on the other, so it must be designed to withstand these large differential pressures. That’s why the statement that the gasket is exposed from a vacuum to about 1000 psi is true.