The internal combustion engine is a complex mechanism in which the energy of the fuel is converted into motion. However, only a third of this energy goes to useful work, and the rest is dissipated in the form of colossal heat. If this heat is not removed, the engine parts will melt in a matter of minutes, and the oil will turn into a coal substance. It is to prevent catastrophic overheating and there is a cooling system, the heart of which is a radiator.
The driver rarely thinks about what is going on under the hood until the temperature arrow hits the red zone. Car radiator is a heat exchanger, whose task is to cool the liquid heated in the engine (antifreeze or rosol) with a flow of oncoming air. Without this unit, the operation of a modern car would be impossible, since the temperature conditions of the engine are extremely rigid and require accurate control.
Understanding the principles of this device helps to avoid expensive repairs and sudden breakdowns on the road. In this article, we will discuss in detail the design, types and features of the cooling system maintenance.
The principle of operation and design of the heat exchanger
Structurally, the radiator resembles bee honeycombs made of thin metal plates and tubes. Hot liquid enters the device from the engine through the upper pipe, passes through the winding channels, giving heat to the walls of the tubes. At the same time, a fan or incoming airflow blows around these plates when moving, instantly carrying heat into the atmosphere. The cooled liquid drains into the lower part and returns to the engine, closing the cycle.
The efficiency of the process depends on the area of contact of metal with air. That is why modern radiators have a complex corrugated structure. Thermal conductivity The material plays a key role: the faster the metal gives off heat, the more efficiently the entire system works. Older models of cars could be found brass products, but today lighter and more efficient alloys dominate.
⚠️ Warning: Even a slight strain of the radiator’s cells (e.g., from stones) can reduce cooling efficiency by up to 30%, leading to constant engine overheating in traffic jams.
The most important element of the design is the radiator cover, which is often underestimated by drivers. It works like a valve, maintaining excess pressure in the system. With increasing temperature, the antifreeze expands, and the pressure increases, which allows you to raise the boiling point of the liquid from the standard 100 ° C to 110-120 ° C. If the pressure exceeds the norm, the valve puts the excess into the expansion tank, preventing the pipes from rupturing.
Why does the system need pressure?
Increased pressure does not allow antifreeze to boil at high temperatures of the engine. In a vacuum or atmospheric pressure, the liquid would have boiled earlier, forming steam stoppers that would disrupt circulation and cause the cylinder block to overheat locally.
Materials of manufacture: aluminum against copper
The choice of material for the production of radiators has always been a compromise between cost, weight and efficiency of heat transfer. For a long time, copper and brass were considered the standard. These materials have excellent heat conduction And they can be easily repaired by soldering. However, they are heavy, expensive and prone to corrosion when in contact with low-quality antifreeze.
The modern industry has switched to aluminum. Aluminum radiators are much lighter than copper counterparts, which has a positive effect on the total weight of the car and fuel consumption. Although the thermal conductivity of pure aluminum is lower than that of copper, engineers compensate for this by increasing the heat exchange area and using special alloys with additives of silicon and magnesium.
Compare the main characteristics of the materials in the table:
| Characteristics | Copper/Brass | aluminum |
|---|---|---|
| Thermal conductivity | Tall. | Medium (compensated by design) |
| Weight. | Heavy. | Lightweight |
| Resistance to corrosion | Low (requires additives) | High (oxide film) |
| Repairability | High (light ration) | Low (requires argon welding) |
| Cost | Tall. | Affordable |
When choosing a replacement, it is important to consider that aluminum radiators They are not subject to quality repairs in garage conditions. If the cells are damaged, a complete replacement of the node is most often required. Copper products can be sealed even with tin if you have skills, but finding them on modern cars is becoming more difficult.
When buying a new radiator, pay attention to the quality of soldering tanks. Plastic tanks should sit on a metal base tightly, without distortions and traces of glue protruding outwards.
Types of radiators in a modern car
Many drivers mistakenly believe that the radiator in the car is one. In fact, there can be several in a modern car, and each is responsible for cooling liquid or gas. The main radiator of the engine cooling system is the most noticeable, it is located in the front of the body behind the bumper grille.
In addition to the main system may be present:
- 🚗 Air conditioner radiator (capacitor) - located in front of the main radiator of the engine, it receives compressed freon for transition from a gaseous state to a liquid.
- ❄️ intercooler - is installed on turbocharged engines to cool compressed turbine air before being fed to the cylinders, which increases power.
- 🛢️ Oil radiator A separate circuit for cooling motor or transmission oil, often found on sports cars and SUVs.
The location of these elements requires special attention when washing under pressure. By directing a jet of water between the bumper grille and the main radiator, you risk bending the thin petals of the air conditioner condenser or main heat exchanger. Deformation This leads to disruption of airflow and loss of efficiency.
Interestingly, some cars with automatic transmission inside the main radiator built-in additional heat exchanger for transmission fluid. This compact solution saves space, but creates a risk of mixing liquids when internal partitions corrosion.
Typical malfunctions and their symptoms
The cooling system operates in an aggressive environment: constant temperature changes, vibrations and chemical exposure to the liquid. Sooner or later, every owner will face problems. The most common reason for failure is corrosion and mechanical damage.
Main signs of malfunction:
- 💧 Antifreeze leak - noticeable drops under the car after parking or a decrease in the level of liquid in the tank without visible external leaks (liquid can burn in the cylinders through the gasket of the HBC).
- 🌡️ Overheating of the engine The temperature arrow goes into the red zone, especially when standing in traffic jams, when there is no blowing on the opposite stream.
- 🌫️ Cheap steam - white smoke with a characteristic sweetish smell of antifreeze indicates boiling liquid.
⚠️ Warning: Never open the radiator cover on a hot engine! The pressure inside the system can reach 1.5-2 atmospheres, and the boiling liquid will escape outwards by a fountain, causing severe burns.
Another hidden problem is the clogging of the cells from the inside. Using tap water instead of antifreeze results in the formation of scale, which clogs the thin channels. Circulation is disrupted and the engine starts to warm up even if the radiator looks whole. External pollution by down and insects also reduces efficiency, so they must be carefully blown out with compressed air.
System replacement and maintenance
Replacement of the radiator is a procedure available even for a novice motorist with a basic set of tools. However, it requires care as the plastic elements on older machines become brittle. Before starting work, you need to completely drain the coolant into a clean container if you plan to use it again.
The dismantling process usually involves disconnecting the top and bottom pipes, disconnecting the fan's electrical connector, and unscrewing the fasteners.
☑️ Checklist before replacing the radiator
After installing a new node and filling the system with antifreeze, it is critical to remove the air traffic jams. To do this, the engine is heated with an open lid (or a special valve) until the thermostat is opened, allowing air to exit and liquids to fill the entire volume. The presence of air in the system is the main cause of local overheating immediately after repair.
The main rule of maintenance: change the antifreeze strictly according to the manufacturer's regulations (usually every 3-5 years), as over time, anti-corrosion additives run out in it, and the radiator begins to rot from the inside.
Questions and Answers (FAQ)
Can I drive without a radiator cover if I lost it?
Yes, but only to the nearest store. Without a lid, there is no pressure in the system, antifreeze boils at 100°C, which is overheating for a modern engine. In addition, the liquid will actively splash outwards when expanding.
Why does the radiator leak if there are no visible holes?
Microcracks in the soldering areas of the tanks or in the honeycombs themselves can only be opened when the metal is heated and expanded. Also, the leak can be caused by corrosive wear from the inside, when the metal turns into dust under the action of old antifreeze.
Which antifreeze is better to pour: red, green or blue?
Color is not the standard. It is important to look at the car manufacturer’s tolerances and chemical composition (G11, G12, G13). Mixing different types of antifreeze can lead to the formation of a gel that will clog up dead. heater and the main cooling channels.
Should I wash the system with water before replacing antifreeze?
Yes, distilled water should be washed to remove the remnants of old chemistry and decay products. Normal tap water can not be used because of the content of salts that form scale.