What is typically used to seal the joint between the cylinder head and engine block?

The joint between the cylinder head and engine block is typically sealed using a gasket. A gasket is specifically designed to create a reliable seal that prevents the escape of fluids and gases from the joint under high pressure and temperature conditions. It is usually made from materials that can handle the thermal expansion and contraction experienced during engine operation, ensuring that the joint remains sealed throughout its operational life.

The use of a gasket in this application is critical because it must withstand the unique conditions present in the engine, such as combustion pressures and varying thermal conditions. Gaskets are engineered to fill in microscopic imperfections on surface finishes of the cylinder head and engine block, providing a leak-proof seal. This is essential for the proper functioning of the engine, as any leaks could lead to a loss of compression, overheating, and even catastrophic engine failure.

In comparison, while oil seals are used in engine components to prevent the leakage of oil, and thread sealants are meant for threaded connections, neither serves the same purpose as a gasket in this context. RTV (Room Temperature Vulcanizing) silicone can sometimes be used for certain applications, but it is not the standard for sealing the cylinder head to the engine block due to the specific requirements of maintaining a strong and durable seal under extreme conditions.