There are a variety of reasons why the coolant can boil. But often the problem can be eliminated on their own. As practice shows, in most cases the driver is guilty. After all, the cooling system must be serviced regularly. Let's take a closer look at why the antifreeze boils in the surge tank, and how to fix the problem.
Engine Cooling System
The first thing I would like to understand in more detail is how the engine is cooled. The system as a whole is not complex, but there are some nuances in its work. It must be understood that as soon as you start the engine of the car, it intensively heats up. It has special channels through which the coolant circulates under pressure and withdraws some of the heat. The main elements of the cooling system: radiators, a pump, a thermostat, a cap of the expansion tank (air valve), branch pipes, etc.
The boiling point of antifreeze is greater than water. That's why it is used in modern cars. If we recall the course of physics, then we can conclude that increasing the pressure leads to an increase in the boiling point. Accordingly, the higher the pressure, the higher the temperature of the coolant will boil. But heavy operating modes (for example, standing in traffic jams) inevitably lead to a constant increase in pressure in the system. When it reaches a certain value, an air valve opens, thereby releasing excess steam into the atmosphere.
About regular maintenance
As it was noted at the very beginning of this article, the cooling system must be periodically checked for leaks, the condition of the antifreeze, the efficiency of the pump and the thermostat. If this is not done, then there is a possibility of serious engine breakdown and overheating. Capital repairs - the event is not cheap, so you should not bring this up.
Another important point is the service life of the antifreeze. In many respects it depends on its type. For example, G11 is desirable to change every few years, and G12 + easily withstands about 5 years. In this case, there are recommendations of the manufacturer to the type of coolant and the regularity of its replacement. Therefore, if you notice that the antifreeze boils periodically in the surge tank, this does not mean any mechanical malfunction. It is possible that he simply lost some of his performance characteristics, which is why the boiling point dropped. Well, now we will pass directly to the main problems and methods of their elimination.
Insufficient level of antifreeze in the expansion tank
When there is not enough cooling liquid in the system, the boiling point drops. In most cases, the problem is solved by a normal refill. It is advisable to perform it on a cold one. This is due to the fact that at high temperatures the liquid expands. Therefore, if you pour into the expansion tank to the "minimum" mark, when the cooling system tosola becomes significantly less.
Actually, there is nothing complicated in the refill. Find the expansion tank and unscrew the plug. It can be as ordinary plastic, which does not perform almost any function, and is hermetically sealed. After we have unscrewed it, fill in the necessary amount of antifreeze. It is desirable that the level of antifreeze in the surge tank is between the "maximum" and "minimum" marks. As for the reasons for which the level fell, there are only a few. It is likely that when servicing the system, the antifreeze was not sufficient. The second option is a leak.
Malfunction of thermostat
If you notice that squeezes out the antifreeze from the expansion tank, then this can indicate the wedging of the thermostat. The fact is that it works as a valve and has two positions: closed and open. In the closed position, the system circulates through a small circle. On a large circle, the liquid passes through the radiator, which contributes to its accelerated cooling. If the car engine is cold, the thermostat valve is closed, which contributes to the accelerated warm-up of the power unit. When the engine is hot, the thermostat opens and the coolant circulates through the radiators, where it is cooled by a stream of counter-air or by diffusers.
What do we get if the thermostat sticks? There are two options: the antifreeze is constantly boiling in the expansion tank for hot water. This is due to improper circulation of the coolant. At the same time, the antifreeze is squeezed out of the expansion tank, as it is constantly expanding. This indicates that the valve has jammed in the closed position. The second option - the car will be very long warm up. With any problems with the thermostat, it must be replaced, it is not too expensive to save on such a critical part.
Radiator cooling and its malfunctions
The designers at the stage of creating the car laid down certain data on the rate of movement of antifreeze in the system. Over time, the internal space of the radiator is clogged with salts and sediment. This can not be avoided, although the problem is simply simply eliminated on its own. It is enough to wash the system with special means when replacing the coolant, which will partially or completely remove the sediment formed during operation. As a result, the coolant will circulate faster and more efficiently to cool.
At the same time, do not forget about the radiator from the outside. Since it is mounted behind the front bumper and is cooled by the flow of oncoming air, it gets dirty outward fairly quickly. Honeycombs are clogged and heat transfer is disturbed. Air does not pass through the radiator, which leads to the boiling of antifreeze in the expansion tank. Cells are cleaned with special cleaning solutions at low pressure. It is advisable not to use the car wash, because you can bend the honeycomb.
Air Valve Malfunction
As we have already figured out, the cork of the expansion tank is quite an important element, although many motorists do not change it for the entire life of the car. But then someone will be lucky, because the valve can work properly for a long time, and may fail for a year of operation or even less.
Check the plug for operation is quite simple. To do this, it is necessary to start the car engine and fully warm it. When excessive pressure builds up in the system, the valve should work and excess pressure will be thrown off. You can understand this by the characteristic sound. In addition, failure of the valve will result in extrusion of the antifreeze into the expansion tank. Repair the lid is not subject to, so it must be replaced.
An antifreeze temperature sensor is required not only to monitor the status of the system on the dashboard. He performs another, no less important function. The sensor sends data to the onboard computer and when a certain temperature is reached, it gives a signal to start the cooling fans. If when driving at high speed the diffusers are practically not needed, then in traffic jams they are just necessary.
If something does not work properly, the fans do not start, and the sensor itself is often working normally. The problem may be the breakage of the electrical circuit or the failure of the fuse. You can call the wiring either independently or by an electrician at the service station. After that, the problem should disappear. But first of all it is desirable to check the fuse. For this, it is sufficient to install a new one. The relay is the least likely to fail. On some models of cars it can not be bought in a regular car dealer. In this case, as a temporary solution, you can install a jumper. But you need to understand that the fan will work constantly.
Breach in the system
Leakage of antifreeze is the most common problem. Over time, the nipples dry up, and microcracks appear on them. Also, the fastening points to the radiators and the expansion tank are weakened. As a result, a small leak appears first, which only increases with time. If the problem is not eliminated, then eventually the nozzle can tear. All the antifreeze will pour out, and the engine will overheat if not noticed in time.
To avoid this, it is recommended to periodically change the rubber nipples, inspect the condition of the fasteners, etc. Also, a leak may occur as a result of a malfunction of the air valve. When there was too much pressure in the system, there was a weak point, through which the coolant flows. In this case it is not clear how much antifreeze is poured, because its level will constantly change. It is desirable as soon as possible to eliminate leakage.
The so-called pump is responsible for pumping the coolant through the system. Typically, the water pump is included in the gas distribution kit and varies according to the regulations. Therefore, it is desirable to install a new pump every 70-100 thousand kilometers, in order to avoid problems.
But it happens that there is not enough money for the original pump. In this case, drivers buy an alternative, most often a Chinese substitute, and then wonder why the antifreeze boils. After a while, the pump gives a leak, which can lead to the destruction of its impeller and the entry of plastic elements into the powertrain system. Replacing a faulty pump is not cheap, but it needs to be done as soon as possible. It is not recommended to move independently on the car in this case. Cheaper to pay for the tow truck.
A few tips for motorists
So we figured out the main reasons for boiling and squeezing out the antifreeze. As you can see, there are a lot of them. Often, to identify and fix the problem is simple enough. But nevertheless it is necessary to observe a number of simple rules, helping always to support system of cooling of the motor in a normal condition:
- Regular replacement of antifreeze;
- Checking the operability of the thermostat and air valve;
- Cleaning the radiator from the outside and inside when replacing the antifreeze;
- Inspection of nozzles for defects in the form of cracks;
- Replacement of the pump together with the timing kit.
Actually, nothing complicated, no less than add the antifreeze to the system. But at the same time, non-compliance with the manufacturer's recommendations may lead to more serious problems.
Let's sum up the results
When the car engine overheats, the power unit may not fail. It all depends on the length of the ride at elevated temperature and the design features of the engine. For example, an engine with an aluminum block is afraid of overheating more than others. Therefore, such a motor most often sticks when reaching a critical temperature.
Many motorists know how to add antifreeze, but it does not save problems. After all, you can skip the level sooner or later. As practice shows, serious breakdowns happen at the most inopportune moment. Break the branch pipe can be on the road far from home, and even the expansion tank cap does not give any guarantee. What to do in this case? The main thing is not to panic. If the engine has not been overheated, serious consequences have already been avoided.
To avoid such trouble, it is necessary to follow the recommendations of the manufacturer. It is advisable to buy only original spare parts, because in 90% of cases they are the best. So you know why the antifreeze is boiling in the expansion tank, and what to do in case of such a problem.