Using shop air, this ingenious, simple, time-saving tool holds engine coolant inside the engine, with little or no coolant loss, even when pipe plugs, sensors, valves and other components are removed for replacement or repair. Quickly converts from vacuum to a pressure tester, up to the maximum pressure limit of the included pressure cap. Air requirements for continuous operation: 30 CFM at 120-150 PSI (. 85 cubic meters at 8-10 bar).