Antifreeze foams in the expansion tank: possible causes and solutions

Briefly about the cooling system and antifreeze function

To approach the issue competently, you need to understand what role the coolant plays in the car’s cooling system.

So, antifreeze is designed for effective cooling of various internal combustion engine components. Antifreeze contains polyhydric alcohols, various additive packages, water and dye. This set of components allows the liquid not to freeze at low temperatures. The liquid was specially created so that car enthusiasts could have peace of mind in the cold winter. Antifreeze moves through the system via a pump.

Due to circulation, the operating temperature of the engine is maintained even in extreme conditions. Do not underestimate the role of coolant in the proper operation of a car. Antifreeze requires periodic replacement. It is very important.

Poor quality antifreeze

It was discussed above that antifreeze has a special composition that ensures effective engine cooling. The liquid is designed to protect the components and parts of the internal combustion engine from temperature deformations. Due to its formula, the coolant does not freeze even in severe frost.

If antifreeze foams in the tank, then first of all you should make sure that the product is of high quality. The liquid must circulate throughout the cooling system and all important key components constantly and even while the engine is warming up.

If you fill in a low-quality product, the principles of fluid circulation will not change, but the air that is in the expansion tank will react with elements from the coolant. As a result, the liquid will begin to bubble. Coke and foam are formed.

It often happens that you can see a brown mass in the tank. This is a signal that the antifreeze is of poor quality, was not manufactured using factory technology, but was diluted in the garages of would-be businessmen.

In addition, if they want to save money, sometimes drivers mix two types of incompatible liquids. Antifreeze also foams due to the fact that the liquid poured in is not the one recommended by the car manufacturer.

Foam in the expansion tank.

Hello, please help me with this problem - foam has appeared in the expansion tank, dense, like beer foam or like from a feri.
the foam is white, the antifreeze is green as it should be (changed less than a week ago). I was on two hundred, opinions differed - one said that the antifreeze was scorched, the other said that either the gasket had broken or there was a microcrack in the head. who is right? and what to do? auto-khova, euro2.

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Gasket wear

Many people do not pay much attention to cylinder head gaskets, thinking that it is an insignificant part in a car that simply exists. But such a minor detail can add problems to the driver. If the gasket fails, the driver grabs his head and rushes to the service station at great speed.

In fact, the gasket plays an important role. Let's look at why antifreeze foams in the expansion tank. What problems does this rubber band solve? It prevents moisture from entering the block head into the block itself. When the gasket fails, liquid and free air pass into the expansion tank.

If we add high temperature to this, then remembering the laws of physics, we can conclude: foam will form. It does not appear immediately and in small quantities. If you do not solve the problem immediately, then bubbles will subsequently grow, and then the coolant will turn into a foamy mass. All this will be accompanied by smoke and temperature changes. The car will show normal temperatures.

Foam in the expansion tank: reasons

There are several reasons for the appearance and formation of foam in the expansion tank. But there are only two main ones:

1. The coolant (antifreeze or antifreeze) purchased for the car is not of the best quality, and sometimes it is an outright “mess”.
2. Damage (blowing) of the gasket between the cylinder head (cylinder head) and the cylinder block.

Coolant replacement

This will help if the antifreeze foams in the expansion tank and the liquid itself does not meet the declared characteristics.

First of all, open the stove tap - it’s not difficult to find. It is located inside the car. This is the same tap that regulates the temperature of the heater. The “hottest” position – the tap will be fully open.

Then unscrew the cap of the expansion tank or the filler part on the radiator. Next, you need to drain the liquid from the system - on many cars there is a special tap at the bottom of the radiator for this. If there is none, then the channel is closed with a plug bolt. You should prepare a container for the coolant - do not pour it into the ground. The liquid is drained completely, not forgetting to remove the intake manifold hose - this will help protect against the formation of air locks.

After this, new coolant is added. The manifold hose is installed back and the clamp is tightened. The liquid is poured into the tank or radiator to an average level. If necessary, the level is adjusted. As the temperature rises, the liquid tends to expand. Therefore the level may increase.

Start the engine and warm it up to operating temperature. Only now can you check the fluid level in the tank. If necessary, add coolant. This completes the process and the problem should no longer appear.

Replacing the cylinder head gasket

The procedure for replacing an engine gasket is actually not complicated. Leaks form where the cylinder head connects to the cylinder block. Why does antifreeze foam in the tank? The reason is overheating. In this situation, the structure and the tightness of the gasket are compromised. It is impossible to delay in eliminating such a malfunction.

The gasket changes almost the same on different cars. There are differences in the procedure for dismantling the fasteners. It is worth knowing the tightening torques of the bolts.

To prevent possible disruption of the fastener structure and failure of components and elements, the bolts are thoroughly cleaned. Before unscrewing them, remove excess dirt. If this is not done, then if it breaks, there may be problems with unscrewing.

The bolts are unscrewed as evenly as possible. It is recommended to weaken them from the center. After each bolt is completely loosened, remove the head and change the gasket. To ensure proper installation of the gasket, there are alignment bolts on the block.

Coolant leaking from the reservoir

This is another problem that raises many questions among car owners. What contributes to this? There may be several reasons for this. However, the most important one is a worn-out cooling system. When the engine is running, the pipes and hoses experience strong pressure from hot antifreeze, so during prolonged operation the tank will push out the liquid rather than distribute it throughout the system.

But the problem does not only appear on used cars. The cause may be a faulty expansion tank. This is due to the low quality of spare parts or defects. If there are burrs on the neck of the tank, this indicates that the lid does not close tightly and coolant will splash out through the gap.

Another reason is substandard plastic of the tank. Low-quality material cannot withstand pressure and tears at the seams. In this case, the coolant is poured onto the engine and the entire engine compartment.

Preventive measures

Preventive measures include the following:

• timely replacement of coolant. At the same time, the choice between foreign-made antifreeze and our native antifreeze is a “matter of taste” for every car enthusiast. According to many drivers, there is no big difference between them, except for the cost per unit of volume;
• in the case of the cylinder head gasket (cylinder head), everything is a little more complicated. Here it is impossible to predict in advance at what exact moment the gasket will be “blowed out” and foam will fall into the expansion tank. But if this happens, you need to contact qualified specialists as soon as possible.

No car is immune from the problem of “foam in the expansion tank”. It is important not to get lost, but to solve the problem in a timely manner. Otherwise, you may simply be left without wheels.