Hello, it's your mother calling to remind you to change your coolant.
While rebuilding my engine I had to dig out loads of calcified crud from around the piston liners. This crap was the result of neglect. The dreaded P. O. probably used hose water to top off the coolant and never changed it at all. To keep the system sparkling clean and working efficiently it needs annual maintenance.
See other posts in the cooling section for advise on draining and cleaning the system.
I use about 15% Sierra (non toxic) anti freeze, Red Line Water Wetter, and distilled, yes DISTILLED water from the grocery store.
Radiators and water pumps are expensive. Overheating isn't fun.