I'm still checking into replacing head gasket. In the meantime I have been driving for short distances and not overheating anymore but I am hearing the waterfall sound in the dash. After I let the engine cool I am checking coolant level and it is about 2 inces low. I remove the cap and it rises to the full mark. I feel like I need to flush and bleed the system. I read the article on how to bleed but I am not sure how to completely drain the system.