Modern cars need water cooling. High-performance engines couldn’t otherwise be kept at an optimal working temperature. Defects of the cooling system quickly result in serious engine damage. But also the wrong coolant can damage your engine internally. Read in this article, what to observe with respect to the engine coolant in your car.
What causes the engine to heat up?
Engine heat is generated in two ways: the combustion of fuel and internal friction. In the engine’s combustion chambers, fuel is brought to explosion with several hundred degrees Celsius. Metal is an adequate heat conductor. As the entire engine consists of metal, the heat spreads from the combustion chambers over the entire unit. Furthermore, the engine consists of several hundred moving parts. Although they are always lubricated, a certain internal friction develops, causing additional heat in the engine.
A certain amount of heat is necessary
The engine should not be completely cooled off by the cooling system. A certain engine heat is necessary. Metal expands through heat. At ideal working temperature the moving parts have the optimal mutual distance. Instead of rattling and beating together, bearings, axles and levers have a so-called “sliding fit”, components constantly being in contact with each other. This ensures the optimal power transmission without excessive wear.
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Task of the cooling system
The cooling system’s task is permanently keeping the engine at an ideal working temperature. A mechanically driven water pump constantly pumps coolant through the hoses and ducts of the engine. The coolant releases absorbed heat generated in the engine to the air stream in the radiator at the front.
Although this may sound simple, the system requires additional control. During winter the environmental temperature is often much too cold. If then the radiator allows air to pass through, the engine would never reach the optimal working temperature. In summer it can be too hot, and the radiator is no longer able to generate sufficient cooling. Temperature control in a cooling system takes place by two modules:
|The thermostat valve divides the cooling circulation into two separate circulations. The “big” cooling circuit includes the radiator in the front of the car. The “small” circuit runs separately from the radiator and conducts the engine coolant directly back into the engine. This is very important especially in case of a cold start: assisted by the thermostat a cold engine reaches its optimal working temperature very quickly.|
|If the engine gets too hot despite the completely opened big cooling circuit, a fan starts working, pressing additional air through the radiator and increasing the cooling performance. Depending on the type of car, electrically or hydro-mechanically driven fans are used.|
Tasks of the engine coolant
The coolant performs more tasks than one would think. Of course its primary task is conducting the heat generated in the engine to the radiator. However, it does more:
|– Protecting the cooling system against freezing
– Protecting the cooling system against corrosion
– Lubricating the moving parts in the cooling system
– Protecting the rubber and paper components of the cooling system against dissolution
This is made possible by the right mix of water and coolant. Several things must be observed, here.
Excess is damaging
Water is an ideal heat conductor. Adding more antifreeze agent to the water reduces the water’s heat absorbing capacity. The idea “the more the better” does not apply to adding antifreeze. This applies also to its original task: the maximum freezing protection only occurs at a certain proportion of added agent and water. If the concentration is too high, the freezing point of engine coolant rises and exactly the opposite is reached! A concentration of 55% guarantees a freezing protection until -45˚C. By using antifreeze only as a coolant, the freezing protection is only -15 ˚C.
Additionally, the boiling point of antifreeze shifts. With a higher concentration of antifreeze, the engine might exceed its optimal working temperature, causing excessive damage: the surfaces of the moving engine parts are hardened. If the engine’s working temperature is permanently exceeded, the moving parts exchange too much pressure. This leads to abrasion of the hardened layer, under which the basic material is considerably softer. Once this layer is reached, the parts wear very quickly, reducing the life span of the entire engine.
Checking the engine coolant
The coolant should periodically be checked. According to maintenance schedule it is completely replaced every 50.000 to 100.000 km. In between those intervals its level should be periodically inspected, however not only the level is important. A closer look at the engine coolant itself might give essential information on the engine’s condition: if its colour is too dark or there are oil drops in it, this is an indication for a defective cylinder head gasket. A countercheck can be done at the oil filler cap: if instead of dark, clear lubrication oil, a brownish-white foam can be seen, the cooling and oil system stand in contact with each other. In this case the cylinder head gasket is very probably defective.
Antifreeze is not merely antifreeze
Antifreeze agent consists for 90% of glycol and 10% additives. Glycol is a sugar and main component of the antifreeze. The additives are for lubrication and corrosion protection. It is essential for these additives to match the requirements of the car. The composition of rubber hoses and gaskets vary depending on manufacturer. If the wrong antifreeze is added to an engine, this can have dramatic consequences, causing the engine coolant hoses and cylinder head gaskets to corrode. Using the wrong antifreeze can cause serious engine damage. Fortunately they are easily identified. Antifreeze is distinguished according to colour.
Green, red, blue
For a quick orientation the colour is a safe guideline. It is recommended to stick to the available colour. Never mix agents of a different colour.
The additives can cause a chemical reaction and precipitate the damage to your engine.
Exact information on the right antifreeze can be found in your car manual and in the data on the packaging of the agent.
Changing every season is not necessary
It is unnecessary to drain the antifreeze in the hot season and add it in winter. The agent’s composition allows it to remain in the cooling system all year round. It fulfils an essential task preventing corrosion. Water causes the engine and radiator to rust. This is not beneficial for the engine’s life span. Rust in the coolant can be clearly discerned, colouring it red. In this case, the engine coolant has a typical rusty shade. This is clearly different from the rather pink hue of the antifreeze of the “red” type.
A corroded cooling system can be “saved” by replacing the radiator, pump, thermostat and a thorough rinse. All three components are wear parts, and therefore regular replacement is beneficial. It is important to afterwards add the correct mix of water and antifreeze.
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How to service the coolant
Both concentrate and mixed engine coolant are toxic. The harmful substances can enter the blood circulation through skin contact. Therefore, gloves must be worn when handling coolant and the concentrate should never be consumed. Take care that children have no access to the antifreeze. Glycol is sweet and very tempting for children.
Well mixed, safely driven
As you see, the handling of antifreeze is not as simple as one would think. With a bit of common sense and care the car can be properly prepared for the cold season. A bit of algebra is helpful too. With a tester the concentration of antifreeze can be exactly determined. Taking this as a starting point, it is possible to determine by way of normal percent calculation how much engine coolant must be added. With a bit of common sense, an excessive dose can be avoided. As said earlier: excess is damaging especially when it comes to antifreeze.
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