How do you fix a radiator?

Here is advice: * The best thing to do it to take the radiator to a repair shop and let them handle the repair. They will clean and flush it and repair any leaks. It may be almost as cheap to replace as to repair. Check on the price of a new radiator before paying for a repair. * Most modern radiators are aluminum and plastic composite. They are not economically repairable and therefore should be replaced. NEVER replace the radiator without new hose, new radiator cap and new coolant. A new thermostat is recommended. NOTE: Unless damaged, the chief cause of radiator failure is actually a blown or leaking engine head gasket allowing the cylinder pressure (80-125 PSI to leak into the radiator (max 20 PSI).