Cooling systems can become seriously problematic if the internals are gummed up with sludge and contaminates that can occur on older machines; especially if any of the previous owners used the wrong coolant, or worse, just tap water!
To be sure of a fully functioning cooling system, renew all the various parts that may now be terminally blocked or suffering internal corrosion.
This item and some of the parts below may be required to achieve a fully successful overhaul of the radiator and its associated parts, both for sound mechanical and cosmetic purposes.