Top off the coolant tank, turn the Heater to full hot, start car with cap on 1st notch, not screwed on all the way, let it warm up- maybe drive it around the block a few times.

Eventually as the thermostat warms up and starts to open the system farts out the bubble, and the water level will drop in recovery tank. Top it off again, and then tighten cap.

Check levels again in a few days and top off if needed. This may go on for a few days.

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03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)