Car radiators can have the following issues: The radiator fan is not working properly: The radiator fan helps the vehicle pull air through the radiator. this helps the vehicle remain cool when it travels at slow speeds or when it is idle. If the vehicle is generating a lot of heat when it is driving at low speeds, then the issue might be with the radiator fan. If the radiator fan is not working properly the car could overheat and in the worst cases, the engine might blow up. There is not enough coolant: Coolant levels in the radiator are very important in order to avoid overheating of the vehicle. So make sure that the coolant levels are always maintained or else it could lead to the vehicle overheating. One of the issues that could lead to low coolant levels is radiator leakage. Radiator Leakage: This is one of the most common radiator issues and it is also quite easy to diagnose. If you find that there is a puddle of liquid below the car whenever the car is not in use, chances are there is an issue with the radiator. You can also check for bubbles or steam formation on the radiator to find out if there is a radiator leakage. The water pump does not work: It is the water pump that moves the coolant liquid around the engine in order to prevent overheating. Water moves fro the radiator to the engine and vice versa with the help of the pump. Issues with the pup will lead to issues with the circulation of water and consequently overheat. Rusting: Rusting can lead to corrosion of radiator and leaks. Rusting can cause the efficiency of the radiator to decrease.