In this paper, the amount of wasted heat from different parts of a 12 liter compression ignition engine and their potential for waste heat recovery were investigated. Then, two-stage configuration of organic rankine cycle was introduced for simultaneous heat recovery from exhaust gases and coolant. Finally, parameters like hybrid generated power, engine thermal efficiency and brake specific fuel consumption were studied in different engine speeds and full engine load. As a result, by using this method, it is possible to produce 35 kW hybrid power, which causes 9.5% reduction in brake specific fuel consumption.