I have a radiator leak on my car.
Todays radiators are have an aluminum core and plastic tanks. The area where the tank meets the core is sealed by a gasket. Over time radiators tend to develop leaks in the gasket area. When this happens the usual repair is radiator replacement. There are places that can repair your existing radiator but the price is usually about the same as a replacement. A mechanic can perform a pressure test and determine where the leak is and suggest a repair solution.