A liquidified gas fired system facilitates starting of an internal combustion engine by external heating of the engine coolant and fuel so as to allow periodic shut down in cold weather. The system includes an engine coolant heat exchanger inside a refractory lined fire-box which is heated to incandescent temperatures. Both engine coolant and liquified gas are preheated by regenerative cooling of the combustion products and an auxiliary gas heater is providded for unassisted cold starting of the system.