Drain the cooling system. For additional information, refer to:
Cooling System Draining, Filling and Bleeding (303-03A Engine Cooling - 1.6L Duratec-16V (Sigma), General Procedures),
Cooling System Draining, Filling and Bleeding (303-03B Engine Cooling - 1.6L Duratec-16V Ti-VCT (Sigma), General Procedures),
Cooling System Draining, Filling and Bleeding (303-03C Engine Cooling - 1.8L Duratec-HE (MI4)/2.0L Duratec-HE (MI4), General Procedures),
Cooling System Draining, Filling and Bleeding (303-03D Engine Cooling - 1.6L Duratorq-TDCi (DV) Diesel, General Procedures),
Cooling System Draining, Filling and Bleeding (303-03F Engine Cooling - 1.8L Duratorq-TDCi (Lynx) Diesel, General Procedures),
Cooling System Draining, Filling and Bleeding (303-03F Engine Cooling - 1.8L Duratorq-TDCi (Lynx) Diesel, General Procedures).