I recently got a 1994 302 5.0 f150 with 180,000 miles on it and the radiator needed to be flushed since the coolant was brown. I tried to drain using the petcock but it was clogged so I took the bottom hose off the radiator. After draining all the fluid from the radiator I put the bottom hose back on, took the top hose off, and filled the radiator with water until all the coolant had drained from the top hose. I put two bottles of prestone super cleaner into the radiator and filled it all the way up with water. I also made sure the coolant reservoir was filled with the right amount of water after cleaning it out. Then I ran the engine with the cap off while adding water to the radiator. After it was full, I put the cap on and let the engine run for about 10 minutes. I know I didn't drain the coolant from the engine but I would rather not mess with it as I heard the plugs can break. Can I just keep doing this until all the coolant, dirt, and cleaner is out of there? Is there still air in my cooling system that I need to let out?