Head Gasket
A critical seal compressed between the engine block and the cylinder head, preventing fuel, coolant, and engine oil from mixing or leaking.
The head gasket is a highly durable seal compressed between the engine block (which houses the pistons) and the cylinder head (which houses the valves and spark plugs). It seals the combustion chambers to ensure maximum compression while keeping the engine oil and liquid coolant channels isolated from each other and the cylinders.
Because it is subjected to intense pressure, combustion heat, and thermal expansion, the head gasket is under constant stress. If the engine overheats, the metal block and cylinder head can expand unevenly, warping the mating surfaces and causing the head gasket to fail—a condition commonly referred to as a blown head gasket.
A blown head gasket can cause several severe issues. If coolant leaks into the cylinders, the vehicle will emit white, sweet-smelling smoke from the tailpipe and consume coolant. If coolant mixes with engine oil, it creates a milky, light-brown sludge that destroys the oil's lubricating ability, risking catastrophic engine seizure. Other symptoms include bubbles in the radiator, engine overheating, and low compression.
Repairing a blown head gasket is a major engine rebuild procedure that requires removing the cylinder head, machining it flat, and replacing the gasket. It is a labor-intensive repair, making it one of the most expensive services in automotive maintenance.