Some common signs of a blown head gasket include white smoke coming out of the exhaust, loss of coolant without any external leaks, engine overheating, oil appearing milky on the dipstick, and bubbles in the radiator or coolant overflow tank. To repair a blown head gasket, typically the cylinder head(s) will need to be removed, the old gasket scraped away, and a new gasket installed with proper torque specifications. It is not recommended for inexperienced individuals to attempt this repair as it can be very involved and requires specialized tools.