Bleed from the coolant reservoir. What I have found that works amazing is to add the coolant and jumper the aux water pump. Keep adding the coolant and the aux pump will do the work in getting it circulated and pushing any air out of the system.

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1990 190E 3.0L

I still think the bleeder hose is the best option. You might need to update the coolant reservoir as well but I've never had any issues bleeding the system on my M103s.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

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