The full name of antifreeze is antifreeze coolant. From the name, it can be seen that it has two main functions: first, antifreeze, and second, cooling. Antifreeze can prevent the vehicle's cooling system from bursting when the vehicle is parked in cold winter, and it can 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, which will cause serious water shortage around the cylinder wall, thus making the engine lack of cooling, reducing the strength of the piston, piston ring, connecting rod and other parts, even deforming, and unable to bear the normal load. At the same time, it will also destroy the normal gap between parts, making it impossible to maintain the normal oil film between parts, which will cause the engine to pull and pull, or even damage the whole engine.
in addition, antifreeze has a high boiling point besides "antifreeze". We all know that the boiling point of water is 1℃, and the boiling point of antifreeze is generally 11-12℃, which plays an obvious role in protecting the engine and preventing "boiling". To give a simple example, the working temperature of Santana engine is 9-15℃ and that of Jetta is 85-115℃. If all antifreeze is replaced by water, it will not freeze, and it will be easy to boil in summer.
in addition to the characteristics of "low freezing point and high boiling point", antifreeze also has the functions of corrosion prevention and scale prevention.
If ordinary tap water is used all the year round, the water contains mineral components, especially calcium and magnesium. In high temperature environment, these minerals will react with metal parts and form scale that is difficult to remove. Scale is another killer of vehicle cooling system. The formation of scale in the vehicle cooling system will affect the fluidity of "cooling water" and is also unfavorable 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 concern in this respect. It is 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 the scale problem.
● Selection of antifreeze: The freezing point of antifreeze is 1℃ lower than the lowest temperature in winter
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" type, and antifreeze does not need to be mixed with water when used. In addition, the vehicle manufacturer will also introduce the 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 it is enough to choose products of big brands as far as possible. Such as Shell, Castrol and Great Wall have corresponding products.
the most important thing for car owners is to mark the freezing point on the package. As shown in the figure, the freezing point of this bottle of Shell antifreeze is-3℃. How to choose the freezing point of antifreeze? It is recommended to refer to the lowest temperature in winter where you actually live, and then drop it by 1-15 degrees Celsius. BMW Brilliance BMW 3 Series 25 32i fashionable wooden interior
Most of the antifreeze is not expensive, and the price of mainstream brand products of "universal" antifreeze is basically 4-6 yuan, with a capacity of 4 liters (the average car water tank capacity is almost 4L). The price of original concentrated antifreeze may be a little more expensive, generally about one bottle in 8 yuan, with a capacity of about 1.5L. 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 is different from the recommended replacement cycle of original antifreeze by different car manufacturers, but most of them advise car owners to replace antifreeze every two years, and some manufacturers show that the replacement cycle of original antifreeze is 4 or 5 years. But in any case, in short, we have to change it, 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, and never replace antifreeze when the engine is at a high temperature. On the one hand, there is a risk of scalding, and 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 driven will drop obviously half an hour after the flameout, and the antifreeze can be replaced at this time. Step 1: There are many ways to drain water. The standard operation is to lift the roof and unscrew the drain screw at the bottom to let the antifreeze drain from this drain screw hole. There are certain hardware requirements for using this method, that is, a vehicle lift is needed, and another disadvantage is that the speed will be slower if the antifreeze is put with the water drain screw. There is also a method that is not very standardized, but 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 the vehicle does not need to be lifted up. At the same time, the staff of the repair shop said that it would be faster and more thorough to drain water than to use the drain screw. (We haven't confirmed this statement.) 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, condenser and other places. Therefore, it is suggested that when changing antifreeze, try to choose the antifreeze specified by the original factory, and be sure to avoid the mixing of antifreeze of different brands and models.
of course, if you don't want to use the original antifreeze, decide to change the brand of antifreeze, and you need to flush the cooling system after the antifreeze is completely discharged. The method of flushing is to insert a rubber hose into the liquid storage tank and continuously inject clean water, while the water outlet is kept open to let the clean water 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 make all the old antifreeze in the car flow out. How to judge whether the cooling system has finished flushing? You can judge 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 water flowing out becomes colorless water, it means that your washing work is finished. However, whether you replace it directly or after washing, 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, and everyone does not have to be too entangled. The countermeasure is to leave more allowance for the "freezing point" when purchasing or blending antifreeze.
when adding new antifreeze, you can directly pour about 3.5L (depending on the vehicle model) of antifreeze into the storage tank, and stop filling when the liquid level reaches the upper limit MAX position. At this time, unscrew the drain screw next to the "water supply pipe", and continue to add antifreeze. After seeing the antifreeze pouring out of the drain screw without bubbles, tighten the drain screw. So far, the work of adding antifreeze for the first time and releasing air is basically completed.
after that, start the vehicle, idle for 3-5 MINutes to make the vehicle enter the normal working temperature, and make the newly changed antifreeze fully circulate in the water channel in the vehicle. Then, turn off the engine and open the liquid storage tank, and the liquid level will be reduced. At this time, just add an appropriate amount of antifreeze to keep the liquid level between MAX and min.
The process of replacing antifreeze is troublesome in words and pictures. In fact, if you don't change the antifreeze model, you can avoid 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. The owner 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 not only saves time but also saves money.