Abstract: A cleaning device for heat exchangers mounted on construction machines such as a bulldozer, for example, and for water pipe that can be cleaned without removing the heat exchanger or pipe from a machine, includes a cleaning water storage tank (1) connected to a pump (2) for pumping water under pressure to a heat exchanger (a) through pressure and flow regulating valves (31, 32) and a gas-liquid mixer (5) to which gas is fed from tank (6) for pulsating and producing gas bubbles in the water flow for effecting the cleaning. Flow control valves (7, 9) control the direction of flow through the heat exchanger and a strainer (8) removes the residue cleaned and carried by the water. An accumulator (4) is connected in the flow circuit with the regulating valves (31, 32) to absorb shock when the regulating valve (32) is closed and which functions together with the valves (31, 32) to produce a pulsation in the water flowing in the system.