How do you change a headgasket on a 91 4Runner?

To change the head gasket on a 1991 Toyota 4Runner, first, ensure the engine is cool and disconnect the battery. Remove the intake and exhaust manifolds, along with any accessories blocking access to the cylinder head, and take off the valve cover. Carefully unbolt the cylinder head, replacing the old gasket with a new one, then reassemble the components in reverse order, ensuring all torque specifications are met. Finally, refill coolant and oil, check for leaks, and start the engine to verify proper operation.