The headbolt heater is a device that warms an automobile's engine to facilitate cold-weather starting. Vehicles with the device can typically be readily recognized by the short power cord hanging from the grill or rear of the hood.
In cold weather, an extension cable can be used to connect the vehicle's headbolt heater to electric power. When power is applied, a heating element warms the engine and its motor oil so that the engine will start more easily. Before the headbolt heater was invented, people utilized various means of warming engines before starting them, such as pouring hot water on the engine block or draining the engine's oil for storage inside overnight. Some even shoveled hot coals underneath their vehicle's engine to achieve the same effect.
Andrew Freeman , a North Dakotan, invented the headbolt heater around 1940 and received a patent for it on November 8, 1949 [1]. His device is widely used in many northern U.S. states as well as in Canada and other subarctic countries and comes as standard equipment on most automobiles sold in those places.
