When you drive, the vehicle's engine creates a lot of friction and heat, and the radiator helps to keep it cool. Without a properly functioning radiator, your engine may overheat and fail to work. Luckily, it's fairly easy to sense whether or not your radiator needs help using just your five senses:
When your engine is cool, open the cap of the radiator and look at your cooling fluid. Is it rust colored? If so, you need to contact a radiator services professional and have the fluid flushed out and replaced.
While checking the fluid, also do a quick visual inspection of the rest of your cooling system. Make sure that all of the hoses and belts are attached, and check out the condition of the hoses to ensure they are not frayed, bulging or wearing out.
If you see a puddle of fluid under your car, you can taste a bit of it on your fingertip. If it tastes sweet, that indicates that it is radiator fluid leaking. However, keep in mind that radiator fluid is toxic. While a small finger-full will not kill you, it's safer to simply smell it.
If you can smell the sweet odor of antifreeze in a puddle underneath your car or if you smell it as you are driving, it is likely leaking out of your system.
Additionally, if you smell a burning odor from your engine, your radiator is likely the culprit, and if it is not your radiator, the issue may be related to one of your other cooling system components such as the thermostat, the radiator fan or the water pump.
An engine that feels hot can be another sign of cooling system issues. If your engine is hot while idling but cool when you rev it, the coolant may not be flowing as it should, and there could be blockages in your hoses or the radiator itself.
To check, feel the radiator hose while the engine is hot. If you can squeeze it, that indicates a flow problem due to an air bubble or built-up sediment. If it's working correctly, the hose will be pressurised and impossible to squeeze.
There are even subtle auditory clues that may indicate a radiator issue. Namely, if the radiator is leaking, you may hear a hissing noise come from under the hood.
Another thing to listen to is the advice of a radiator services professional. If you are constantly adding fluid to your cooling system, that is a sign that it is draining when it shouldn't, and you should talk with a radiator services professional to "hear" what they advise.