Radiator cap off, front of the truck pointed uphill. Run the engine for a while. It has to get hot to open the thermostat and flush out the air. I let mine run for maybe 20 minutes. Watch the fluid in the radiator. At first you'll see bubbles. Once you see no bubbles, you're probably done.I think I may have an air bubble or something, my temp gauge will go to 3/4 H then drop to the middle sometimes, is there a way to bleed the radiator? I didn’t notice a bleed valve or anything?