How vehicle's Cooling System works: The Radiator

What is a Cooling System? 

A vehicle engine produces a lot of heat when it is running, and must be cooled continuously to avoid engine damage. If the engine temperature is too low, fuel economy will suffer and emissions will rise. If the temperature is allowed to get too hot for too long, the engine will self destruct. Generally this is done by circulating coolant liquid usually water mixed with an antifreeze solution through special cooling passages. Some engines are cooled by air flowing over finned cylinder casings.

A Radiators Role

A radiator is one aspect of the Cooling System that keeps your vehicle’s engine operating at ideal temperatures.  The radiator, located in the front of the car, is a type of heat exchanger designed to transfer the heat from the hot coolant fluid inside to the air outside, thereby cooling the fluid, which in turn cools the engine via a fan. Radiators are also often used to cool automatic transmission fluids, air conditioner refrigerant, intake air, and sometimes to cool motor oil or power steering fluid.

Most modern cars use aluminum radiators. These radiators are made by brazing thin aluminum fins to flattened aluminum tubes. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator.

The tubes sometimes have a type of fin inserted into them called a turbulator, which increases the turbulence of the fluid flowing through the tubes. If the fluid flowed very smoothly through the tubes, only the fluid actually touching the tubes would be cooled directly. The amount of heat transferred to the tubes from the fluid running through them depends on the difference in temperature between the tube and the fluid touching it. So if the fluid that is in contact with the tube cools down quickly, less heat will be transferred. By creating turbulence inside the tube, all of the fluid mixes together, keeping the temperature of the fluid touching the tubes up so that more heat can be extracted, and all of the fluid inside the tube is used effectively.

Radiators usually have a tank on each side, and inside the tank is a transmission cooler. In the picture above, you can see the inlet and outlet where the oil from the transmission enters the cooler. The transmission cooler is like a radiator within a radiator, except instead of exchanging heat with the air, the oil exchanges heat with the coolant in the radiator.


Common signs of a faulty Radiator

When the radiator isn’t working properly, you might notice several symptoms

  • Overheating engine

A common sign that something is wrong with the radiator is when your engine starts to overheat. This can be caused by a faulty thermostat. When a defective thermostat no longer opens, the engine will overheat and cause a breakdown.

  • Leaks

You might notice coolant leaking under the vehicle. It can be a red, yellow, or green fluid. When the radiator is leaking, coolant levels become too low, and when there isn’t enough coolant to reduce the heat, the engine might become too hot.

Radiators are made of metal and plastic. And because plastic isn’t as durable as metal, it’s typical for these components to become brittle and start cracking—hence the leaks.

  • Shifting issues

If you have an integrated transmission cooler, you might notice trouble with shifting as the fluid becomes contaminated with coolant. This problem stems from cracks and faults in the system.

  • Fluid discoloration

Vehicle coolant is commonly bright yellow or green. Sometimes it can be pink or red. It flows freely between the radiator and the coolant passages located in your car’s engine. If you have a bad radiator, deposits and sludge can contaminate the coolant and turn it into a rusty color—it may even look like oil. Look in your coolant overflow tank and inspect the color. If it’s contaminated, it may also appear thicker. This causes trouble with the flow and leads to a clogged radiator. A radiator flush might be a solution in this case.

  • Exterior fins blocked

Radiators need maximum airflow for proper cooling. The thin tubes running in the front, the ones that look like fins, carry the hot coolant away from the engine. When you drive, air passes over the fins to lower the temperature of the coolant. If these fins become clogged by debris, leaves, bugs, or dirt, airflow can become compromised. The coolant can’t go down in temperature as it should. With many vehicles, there is enough room to spray off the radiator with a garden hose to keep the air flowing freely. In addition to blocking the air, it’s also possible that you have damaged or bent fins. They are delicate, which means any flying dirt or debris could lead to damage. It’s also possible that you damaged them during installation or while spraying water on them (particularly if the water pressure is too high). If you have damaged fins, a clog can occur in the radiator, leading to an overheating engine.

  • Passenger heater not functioning

Another noticeable sign of a bad radiator is when your heater doesn’t work as it should. Your cabin heater relies on the hot coolant that passes through the core. This produces the hot air that gets blown into your car. If your radiator is leaking or is clogged, you may not get the heat you need on that cold winter day.

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Posted on Sep 23, 2020 by Auto Repair Directory

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