Hello Elizabeth,If it has a cracked Block or the sleeve has slipped getting the air out of the water is not going to help.But you do not have to use sodinm to get the air out because it is not going to work.But most of these cars has bleeder plugs on them and they are useual on the thermostat housing and the heater hoses and you can losen them up a you fill it up with anti freezeand keep a watch on the bleeder plug as you fill and when you see the anti freeze come out of the bleeder plug thighten it back up and finish filling and you should have all the air out of it.