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 connected to a pump for pumping water under pressure to a heat exchanger through pressure and flow regulating valves and a gas - liquid mixer to which gas is fed from tank for pulsating and producing gas bubbles in the water flow for effecting the cleaning . flow control valves control the direction of flow through the heat exchanger and a strainer removes the residue cleaned and carried by the water . an accumulator is connected in the flow circuit with the regulating valves to absorb shock when the regulating valve is closed and which functions together with the valves to produce a pulsation in the water flowing in the system .