The full name of antifreeze is antifreeze coolant. As can be seen from the name, it has two main functions: the first is to prevent freezing, and the second is to cool down. Antifreeze can prevent the vehicle's cooling system from bursting when the vehicle is parked in cold winter, and prevent "boiling" in summer.
What is boiling?
We often say "boiling" means that the cooling water in the engine water tank reaches the boiling point and produces a lot of steam, just like boiling water at home. Because the water temperature reaches the boiling point, a large number of bubbles will be generated, and a part of the cooling system will be occupied by bubbles, resulting in serious water shortage around the cylinder wall, which will lead to insufficient cooling of the engine, reduce the strength of the piston, piston ring, connecting rod and other parts, and even deform, and cannot bear normal loads. At the same time, it will destroy the normal gap between parts, make the normal oil film between parts unable to be maintained, cause the engine to pull, and even damage the whole engine.
In addition, besides "antifreeze", antifreeze also has a high boiling point. We all know that the boiling point of water is 100℃, and that of antifreeze is 1 10- 120℃, which plays an obvious role in protecting the engine and preventing "boiling". For a simple example, the operating temperature of Santana engine is 90- 105℃, and that of Jetta is 85- 1 15℃. If all antifreeze is replaced by water, it will not freeze and it will boil easily in summer.
The antifreeze not only has the characteristics of "low freezing point and high boiling point", but also has the functions of corrosion prevention and scale prevention.
If you use ordinary tap water all the year round, the water contains mineral components, especially calcium and magnesium. In high temperature environment, these minerals will react with metal parts to form scale that is difficult to remove. Scale is another killer of vehicle cooling system. The formation of scale in vehicle cooling system will affect the fluidity of "cooling water" and is not conducive to the heat dissipation of various components. Over time, it will affect the normal operation of the vehicle cooling system. However, if special antifreeze is used, there is no problem in this respect. Not only corrosion-resistant, but also distilled water is generally used in the production process, and waterproof scale additives are added, so there is no need to worry about scale problems.
● Selection of antifreeze: the freezing point of antifreeze is lower than the lowest temperature in winter 10℃.
At present, there are two kinds of antifreeze in the market, one is concentrated solution, which needs to be mixed with water. The second type is "ready-to-use", and antifreeze does not need to be mixed with water when used. In addition, vehicle manufacturers will also introduce antifreeze of the original designated brand, which is generally concentrated and needs to be mixed with water. Most of the "universal" antifreeze sold in the market is "ready-to-use", so try to choose products of big brands. For example, Shell, Castrol and Great Wall all have corresponding products.
For car owners, the most important thing to pay attention to is the freezing point mark on the package. As the picture shows, the freezing point of this bottle of Shell antifreeze is -30℃. How to choose the freezing point of antifreeze? It is suggested to refer to the lowest temperature in winter where you actually live, and then lower it to 10- 15 degrees Celsius. BMW Brilliance BMW 3 Series 2005 320i Fashion Wooden Interior
Most antifreeze products are not expensive, among which the mainstream brand products of "Universal" antifreeze are basically 40-60 yuan, with a capacity of 4 liters (the capacity of general automobile water tanks is almost 4 liters). The original concentrated antifreeze may be a little expensive, generally about one bottle in 80 yuan, with a capacity of about1.5l. When replacing antifreeze, it needs to be added in proportion. Generally, the ratio of antifreeze to water is 1: 1 or 1:2.
● The replacement cycle of antifreeze and the recommended replacement cycle of original antifreeze will be different for different automobile manufacturers. However, most car owners are advised to replace vehicle antifreeze every two years, and some manufacturers show that the replacement cycle of original antifreeze is 4 years or 5 years. But in any case, in short, we have to change, which is nothing more than the length of the replacement cycle.
When replacing antifreeze, the first and most important step is to wait for the vehicle to cool down. Never replace antifreeze when the engine is at high temperature. On the one hand, there is a danger of scalding, on the other hand, releasing antifreeze during "hot car" will also affect the cooling of the vehicle.
Generally, the water temperature of a hot car that has just been driven will drop obviously after half an hour of flameout. At this time, the antifreeze can be replaced. Step 1: There are many ways to drain water. The standard operation is to lift the roof, unscrew the drain screw at the bottom, and let the antifreeze drain from this drain screw hole. There are certain hardware requirements for using this method, that is, the vehicle needs to be lifted, and there is another disadvantage that the speed will be slower if the antifreeze is put with drainage screws. There is another method that is not very standardized, but it is very practical and is adopted by most repair shops (non-4S shops). The advantage of this operation is that the water is released quickly and there is no need to lift the vehicle. At the same time, the staff of the repair shop said that drainage would be faster and more thorough than using drainage screws. We haven't confirmed this statement yet. However, no matter which way the water is drained, it is impossible to clean all the antifreeze in the car, and there will still be a lot of antifreeze left in the engine water jacket and condenser. Therefore, it is suggested that when replacing antifreeze, try to choose the antifreeze specified by the original factory, and be sure to avoid mixing different brands and models of antifreeze.
Of course, if you don't want to use the original antifreeze and decide to replace the brand antifreeze, you need to flush the cooling system after the antifreeze is completely discharged. The flushing method is to insert a rubber hose into the liquid storage tank, continuously inject clean water, and at the same time keep the water outlet open, so that the clean water can flow out smoothly from the bottom. In the process of flushing, it takes about 3-5 minutes to start the vehicle briefly and turn on the warm air, so the clean water must be circulated. The purpose of this is to let all the old antifreeze in the car flow out. How to judge whether the cooling system has been flushed? You can tell from the color of the water flowing from the bottom that the color of the water mixed with the old antifreeze should be light pink or light blue. If the flowing water turns into colorless water, it means that your washing work is finished. However, whether it is replaced directly or after cleaning, it is possible to leave old antifreeze or clear water in the cooling system. This will weaken the "anti-freezing" ability of the new antifreeze. This problem is basically inevitable, so you don't have to be too entangled. The countermeasure is to leave more allowance for "freezing point" when purchasing or blending antifreeze.
When adding new antifreeze, you can directly pour about 3.5L antifreeze (depending on the vehicle model) into the storage tank, and stop filling when the liquid level reaches the upper limit MAX position. At this point, unscrew the drainage screw next to the water supply pipe and continue to add antifreeze. After seeing that there is no air bubble when antifreeze flows out of the drainage screw, tighten the drainage screw. At this point, the work of adding antifreeze and releasing air for the first time is basically completed.
After that, start the vehicle and idle for 3-5 minutes to make the vehicle enter the normal working temperature, so that the newly changed antifreeze can be fully circulated in the waterway of the vehicle. Then turn off the engine and open the liquid storage tank, and the liquid level will drop. At this point, just add an appropriate amount of antifreeze to keep its liquid level between MAX and min.
The process of replacing antifreeze is more troublesome in words and pictures. In fact, if you don't change the antifreeze model, you can save the washing step, so the whole process of replacing antifreeze can be completed in less than half an hour, which is very convenient and basically has no technical difficulty. Car owners can find a repair shop or a quick maintenance shop at will, and there is no need to run a 4S shop specially for this small project, which saves time and money.