Rob told me to do this when my car was doing the same thing your car is just a couple of weeks ago. Un-attach the top radiator hose, open the heater valve, fill up the coolant system using the top radiator hose. When it some coolant in the block, heater, and intake, turn on the engine and continue filling up the system the same way, until coolant starts coming out the top radiator hose. Quickly attach the hose to the radiator, to protect our F***ed up envirmonment as little as it might, and fill up the radiator with coolant, let the car run with the cap off to make sure there is no air in the system, and top off. put the cap on while the car is running. Thanks reading this long and boring how-to. Don't drink the coolant.