This is interesting .Do i need the engine running at the same time ? Can you give me more information please?. or be more specific .

No, you don't need the engine running nor do you need the car on. Just start adding coolant through the reservoir and when it starts to rise or look like its full (usually after maybe a gallon or less) jumper the aux wp pump and you'll see the coolant start to go down and you will hear it gurgling as it flows through the heater core because it's pushing the air out. You can listen as its circulating the coolant through the engine block and feel it moving through the hoses. Leave the pump running and keep adding coolant until it is full. The idea came to me when I was wiring my aux wp to use it as an aux wp to keep engine temps down after I shut the engine down. Usually the temps skyrocket to near 120 after driving in 115 summer heat and letting the engine sit. When I saw how quick the temps came down after shutting the engine off, I realized the aux wp really moves a lot of water within the system so I started to use it to help circulate the coolant during refills when I drained my coolant. It only takes about 5-10 minutes max. Here's a video of how well the aux wp works by quickly moving stagnant coolant from a heat soaked engine. https://drive.google.com/file/d/1ckmyET4KMGXuI8WkP5f1vSvz3muRdhO1/view?usp=sharing

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1990 190E 3.0L