flush the heater core, by removing the hoses off the engine, then flush it with a garden hose.
then fill the rad wait for the engine cooling fans to come, this can take a while as you already found out, 15 to 20 minutes easy. now on top of your t stat housing is a bleeder screw, when the fans come on, you know the t stat has opened, now open the screw a few turns till a solid stream of coolant comes out., shut screw top of the rad. and that should do it. i leave the cap off the whole time while its warming up, if coolant burps out, let it, its normal. when the t stat opens the level should in the rad should drop. top off as needed.
