How do you replace the head gasket on a 2001 Buick century?

To replace the head gasket on a 2001 Buick Century, start by disconnecting the battery and draining the coolant. Remove the intake and exhaust manifolds, along with any components obstructing access to the cylinder head. Carefully unbolt the cylinder head and replace the old gasket with a new one, ensuring the surfaces are clean. Reassemble everything in reverse order, torqueing the bolts to the manufacturer's specifications, and refill the coolant before starting the engine.