Problems with a vehicle's radiator and coolant system are indicated by warning lights on a car's dash, as well as physically detectable signs with the vehicle itself. Engine overheating is the most frequent symptom of radiator problems, which can have multiple causes, including low coolant levels, broken fans or hoses, or a damaged radiator.
Most vehicles display a warning light if the engine overheats. If such a warning is activated, stop driving immediately, turn off the engine and allow the radiator to cool at least half an hour before attempting to diagnose or solve the problem. A different warning light shows when coolant levels are low. If this light remains on after the vehicle is first started, the radiator coolant level should immediately be checked, following the instructions in the owner's manual, and refilled if low.
To physically check a radiator's condition, wait until the engine is cooled, then check the coolant levels and color. Brownish coolant indicates rust that may interfere with the coolant's effectiveness. Also look for coolant leaks in the hoses and the radiator itself, especially if the coolant level is unexpectedly low. Fluid collecting under the car can be a symptom of a major leak. In the case of any problems, take the vehicle to a qualified mechanic to inspect the radiator system.