mechanic

Did you remove the thermostat after replacing the radiator or during the replacement process of the radiator? Removing the thermostat is worse than having a plugged up radiator. A properly rated and working thermostat, "IF"all other cooling components functioning as they were designed will keep the coolant from reaching its boiling point. The cooling system is just like a pressure cooker or putting a lid on a pot of hot water, the rad cap helps build pressure, while the thermostat acts as a popet valve, allowing a lil hot (near boiling) coolant from boiling over. Another thing could be the radiator is to small of a core to hdndle the tcks engine coolant needs, cores to small, not enough core or a couple rows of cores crimped off, not letting the fluids circulate efficiently. If you have no boil overs, no oil in water or water in oil, your heads and gaskets are fine, but there may also be debri from yrs of chemical electrolosis build up or from the previously damaged pump or gasketing material clogging the cooling system.