A block heater is an electric heater that heats the engine of a car; they connect to the normal AC power lines (nominally 120 volts in North America). This allows easier starting in cold temperatures, by keeping the coolant warm. Heaters are also available for motor oil so that it does not gel and the viscosity is low as well as aiding the vaporization of the fuel. In addition to easier starting, block heaters reduce pollution as cold engines have much higher emissions.

Block heaters are often standard equipment for vehicles sold in colder climates, and are common in places like Canada and Finland. In extremely cold climates, electrical outlets are sometimes found in public or private parking lots.

Factory installed block heaters are usually inserted into a freeze plug manufacturing hole in the cylinder block, heating the metal, coolant and oil. Although identical heaters are available and can be installed fairly easily, more commonly after market heaters are attached to the oil pan, sometimes with magnets, or a heated dipstick may be used. An alternative to block heaters is a battery warmer which keeps just the battery warm. This maintains the efficiency of the battery, which is highly dependent on temperature, and is cheaper than heating the entire engine block. Heated blankets are available for the entire engine area, as well. A standard timer switch can be used with any of these heaters, so that it does not have to be left on all the time. This can help lower the electrical costs of owning and using a block heater.

Engine technology | Auto parts