Head Gasket

Category: automotive

The seal that sits between the engine block and the cylinder head.

The head gasket is the "pressure boundary." It keeps oil, coolant, and combustion gases in their own separate zones. If it fails ("blown head gasket"), oil and coolant mix together, often creating a "milky" sludge in your oil and causing the car to white-smoke out of the exhaust.

Common Examples

• The engine overheating combined with white smoke from the exhaust confirmed that the head gasket had failed, mixing coolant and oil.
• A blown head gasket is a major repair that requires removing the engine head, making it one of the most expensive engine-related jobs.