fill radiator for f150

You add coolant to reservoir. If no radiator cap and radiator is empty, you might remove upper radiator hose and add coolant that way? I can't see anything from here? If I missed the point of your post you will need to enlighten me. You add coolant on a cold engine. You need to check coolant level in reservoir several times, To make sure you don't need to add more coolant. Your owners manual has some reservoir info. fleet.ford.com has your owners manual, it's free to read online.

On my 2010 f 150 V8, completely changing the coolant is a bitch. The entire system holds about 16 quarts (four gallons) The radiator itself only holds a little over four quarts. The bottom radiator hose connections sits higher than the connection to the block. So only 4 quarts can be drained from the radiator drain plug. I had to crawl under the vehicle and disconnect the lower hose at the block. And the connection is in a cramped location. Even at the dealership, when they flush the system with a machine, they state they can only remove about 80 percent of the old coolant, meaning about three quarts of old coolant remain in the engine.