Which of the following is a cause of cylinder head gasket leakage?

• A. Reusing a permanently compressed gasket
• B. Improper Installation
• C. Installing a damaged or defective gasket
• D. Improper torque of the cylinder head: either too tight or improper torque sequence

Answer: (A)

When a cylinder head gasket leaks, the seal between the head and the engine block is compromised because the gasket material can no longer maintain the needed compression. A gasket that has been permanently compressed has been squeezed beyond its elastic limit and loses its ability to spring back to the correct thickness and shape. That means it cannot form a reliable seal under the high pressures of combustion and the supporting coolant/oil passages, so leaks develop. Reusing such a gasket guarantees this loss of sealing capability because the material has already been deformed and won’t seal properly again. While improper installation, a damaged or defective gasket, and improper torque can also cause leaks, the direct, root issue described here is reusing a permanently compressed gasket, which has already lost its sealing integrity.