A vehicles radiator is an integral part to the continued operation of an engine, without it, the vehicle would seize up due to over heating. Radiators transfer thermal energy from one source to another in order to either cool or heat up an object. Though the name may imply that the heat escapes through thermal radiation, actually the heat is transferred via convection.
The principals behind a functioning radiator are simple, a coolant (usually water based with glycols to prevent freezing), is passed through an engine block where it becomes heated. It is then sent to the radiator where the coolant is distributed around the radiator core, it then cools as it passes through the various radiator tubes. The tubes circulate the coolant as it transfers its heat to the tubes, which transfer its heat to the fins found in between every row of tubes. These fins then disperse the heat into the open air. However, standing air cannot capture the heat fast enough and fans are used to help facilitate this. The reason that the radiators are usually found at the front of a vehicle behind the grill is to help cool the radiator as it moves.
There are various reasons for radiator malfunction, but usually a common culprit is simply age. Considering the heavy use of the radiator as well as the fact that it is exposed to the elements at the front of the vehicle, it is only a matter of time before it begins to malfunction. Radiator maintenance can prolong its life span, but problems begin to arise after about 5 years for many vehicles. What follows are a few common problems usually found with radiator malfunctions.
Rust is usually the greatest reason for a radiator to fail over time. There are various chemical reactions that can cause rust to start forming, salt and humidity are other factors. When rust starts to form, it will slowly decrease the radiators capabilities till it finally breaks down completely. You will notice a slow and gradual increase over time in the temperature of your engine. Rust is not a problem that immediately causes the radiator to break. If you notice rust forming on the exterior of the radiator, there are ways to remedy this, however if rust begins to form on the inside, it is only a matter of time before the rust takes over.
Faulty epoxy and solders are often reasons for a radiators failure. Epoxy joins your radiators seems together and are often undone by extended use. Solders attach the fins to the tubes themselves and are rather delicate which make them prone to malfunction. Both the epoxy and solders can be viewed, and if inspected a faulty or failing one can be fixed. However, noticeable problems may not arise until more than one give out. The reason is that there are numerous points for the epoxy and solders, so a single spot may not noticeably reduce the cooling of the radiator, but it does put stress onto the other functioning parts, which then makes them more prone to malfunction.
If the coolant cannot flow unobstructed throughout the radiator, it will not cool the engine effectively. Often, mineral deposits build up in the smaller nooks and crannies of the radiators core. When the flow of the coolant becomes too restricted at these points, your engine will not function properly as it will always be overheated. The only tell sign of this is if your vehicle runs a bit sluggishly, and obviously if it is overheating.
There are numerous other problems that can occur, ranging from brittle hoses and damaged water pumps, to electrical problems and malfunctioning thermostats. Often times the best case scenario if you suspect something is wrong, is simply to have your vehicle checked, and if needed, have a cooling system repair done. It is prudent to take preventative measures rather than replace something after it is entirely broken.