Radiatorinfo.Com

Radiator information on all types of vehicles for the radiator industry and general public.
http://www.radiatorinfo.com/

Automotive Overheating Troubleshooting

If you keep a car long enough, you'll get cooling problems. The bad news is that overlooked, ignored or unchecked, cooling problems lead to ghastly expenses. The good news is that caught early, cooling problems are relatively inexpensive to fix.
http://www.troubleshooters.com/toverheat.htm

How Stuff Works: How Car Cooling Systems Work

Tutorial with pictures and animations, including the description of the wax in a thermostat, with related links.
http://www.howstuffworks.com/cooling-system.htm