The radiator on your car ensures that the engine in your car stays cool.

The radiator does this by way of cooling the coolant coming from the engine.

The cooling involves a water pump, radiator, thermostat, and various hoses, valves, and tanks that connect to the engine. The pump pushes water or coolant into the engine block where the liquid heats up. The thermostat controls how long the coolant stays in the engine. When it has heated up enough, the water is returned to the rad where it is passed through various small tubes and into the fins of the rad. If needed, a fan blows on the rad so the heat passes from the liquid through the metal and into the air around the rad. The thermostat again measures the temperature of the water to make sure it has cooled down enough. When it has cooled, it is again pumped into the engine to absorb more heat.

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The rad is obviously the most well known part of the cooling system, but it’s frequently not the culprit when it comes to a malfunction.

Here are some of the most common repairs to a vehicle’s cooling system:

  • A failed thermostat. The thermostat is the most common culprit when a vehicle overheats. The thermostat isn’t actually part of the rad itself, but a type of valve that controls how much coolant can flow into and out of the rad. This helps keep the engine at optimum operating temperature. When the thermostat fails, the car begins to overheat very quickly.
  • Leaky radiator hoses. The most common source of a leak within the cooling system isn’t the rad, but the radiator hoses. The hoses link the radiator to the engine and allow coolant to flow between the two.
  • Radiator leaks. Leaks in the radiator itself are harder to locate and repair than problems with hoses. Look for bubbles or steam coming from the radiator to signal the location of a leak.
  • A failed water pump. The cooling system uses a pump to move the coolant throughout the engine in order to regulate the temperature. If the water pump fails, the water no longer circulates properly and the car will overheat. A broken water pump is fairly common.
  • Cooling system obstructions. Obstructions can take the shape of engine “scale” blocking the cooling passages in the engine or radiator, which makes it difficult for coolant to move efficiently. Obstructions can also happen when something restricts the flow of air through the radiator, which in turn makes it hard for the radiator to transfer heat to the air.
  • A failed radiator fan. Modern cars use an electric fan to pull enough air through the radiator to keep the car cool at idle and low speeds. A car that does fine on the freeway but overheats at idle or in traffic probably has a problem with the radiator fan.