Some symptoms of a clogged radiator are overheating of the engine, a temperature gauge that register a high reading on hot days and when an air conditioner is on, and higher than usual coolant consumption. The causes of a clogged radiator are debris, corrosion and an internal buildup of deposit that lead to a decreased amount of coolant flowing through the radiator.
These causes of a clogged radiator lead to the mentioned symptoms. One way to detect a clog is to use an infrared thermometer. Another method to diagnose the problem is to do a radiator efficiency test that involves measuring both the inlet and outlet coolant temperatures. A blocked radiator may require either cleaning or replacing it.