Engine preheater

A heater for the coolant of a liquid cooled engine, said heater being of a type adapted to be connected in a hose between a liquid cooled engine and a radiator, said heater comprising a housing having a passage extending therethrough for passage of coolant through said heater, said housing having first and second end sections and an intermediate section, said intermediate section being cast of heat conductive material and being located between said end sections, said end sections being adapted to be connected to a radiator hose, an electric heating element cast in place in and embedded in said intermediate section and separated from the passage through said housing by part of said housing, whereby coolant flowing through the passage in said housing is inhibited from direct contact with said heating element but indirectly is heated thereby, said heating element having exposed terminals, a thermostat located in heat transfer relationship with said housing on the side of said heating element remote from said passage, said thermostat being responsive to the temperature of said heating element for interrupting the supply of power thereto when the temperature sensed by said thermostat exceeds a predetermined upper limit, a plug adapted for electrical connection to said heating element via said terminals, said thermostat being incorporated in said plug, and means acting between said housing and said plug releasably biasing said plug towards said housing and also biasing said thermostat against said housing to assure good thermal contact between said thermostat and said housing.