An outside circulation device for engine bench test coolant

The utility model disclosed a coolant outside loop apparatus for engine pedestal testing, wherein, a coolant circulation passage is extended from an output of the engine. The coolant circulation passage goes through a heat exchanger, and joins with an input of the engine to form a closed-cycle type. Valves of normally off are arranged on a cool-end pipeline of the heat exchanger. A heat meter is arranged on the output of the engine, and a control unit is connected with signal wire. The signal wire of the control unit is connected with valves and an alarm device. Two temperature values are arranged in the control unit, one is maximum coolant temperature which the engine can bear, and the other is suitable coolant temperature for the engine. According to the closed-cycle coolant circulation type, scale is rarely furred in the engine. Water capacity is very little, warm-up period is reduced, and the function is enhanced. The quality and reliability of the engine pedestal testing are both improved.