What are the signs of a blown head gasket?

Common symptoms of a damaged engine cylinder head gasket include a significant drop in power, abnormalities in the cooling system, and oil-water mixing. When the cylinder head gasket seal fails, compressed gas leaks from the combustion chamber, resulting in weak acceleration, rough idling, and potential carburetor backfire or black smoke from the exhaust during rapid acceleration. Regarding the cooling system, the radiator may exhibit frequent boiling with bubbles, an oil film visible on the coolant surface, and in severe cases, white steam emission from the exhaust. The lubrication system shows signs such as rapid oil degradation, air bubbles in the oil pan, decreased oil pressure, and intermittent blue smoke from the exhaust. Mechanical abnormalities are also characteristic, including hissing leakage sounds or metallic knocking noises at the cylinder head joint. Notably, cylinder head gasket damage is often accompanied by abnormal coolant temperature rise. If abnormal coolant consumption is observed along with milky oil discoloration, immediate inspection is necessary. Regular verification of cylinder head bolt torque, use of standardized coolant and oil, and avoidance of prolonged engine overload are recommended preventive measures against cylinder head gasket failure.