Yep. I just did this yesterday after a thermostat replacement last week. If you dont let the air out, causes issues. My overflow tank would be full and the radiator level down. Not overheating, running fine. Upper hose starting to bulge, clearly overpressured. Took me about 30 min also, but once it cleared up, running perfect now. Simple fix. Much better than the terror of a head gasket job.