Kim, flush the radiator with a garden hose but put it in the bottom hose fitting on the radiator. This is called backflushing. Water goes the opposite direction as the water pump flows and tends to lift out the rust and junk better. Let it go for a while until there is clean water coming out. This is an old trick from radiator shops back when there were no pressure caps and keeping cool was really needed to keep it below 212.
