Broken cylinder head gasket - how to find out?

Breakdown of the cylinder head gasket leads to such unpleasant consequences as overheating of the internal combustion engine, poor operation of the stove, the appearance of exhaust gases from under the hood of the car, the appearance of an emulsion in engine oil, the appearance of white smoke from the exhaust pipe, and some others. If the above symptoms or one of them appear, you need to check the cylinder head gasket. There are several ways to do this. then we will look at why the cylinder head gasket breaks through, what consequences this leads to, and what to do if this trouble happened to the engine of your car.

Signs that the cylinder head gasket has broken through

The task of the cylinder head gasket is to ensure tightness, and to prevent the penetration of gases from the cylinders back up into the engine compartment, as well as the mixing of coolant, engine oil and fuel with each other. In a situation where the cylinder head gasket is broken, the tightness of the block is broken. The following signs will tell the car owner about this:

Signs of a burnt cylinder head gasket

• Exhaust gas outlet from under the cylinder head. This is the simplest and most obvious sign. When the gasket burns out, it begins to let exhaust gases through, which will go into the engine compartment. This will be seen visually, as well as tangibly by ear - loud sounds will be heard from under the hood, which are simply impossible not to notice. However, if the burnout is small, then you need to pay attention to other signs.
• Shooting between cylinders. External signs will resemble those that appear when the internal combustion engine “troits”. There is a mixing of the fuel mixture from one cylinder with the exhaust gases in another. usually, in this case, it is difficult to start the internal combustion engine, however, after warming up, it continues to work steadily at high speeds. To determine the breakdown, you need to measure the compression of the cylinders. If this mixing occurs, then the compression value in different cylinders will differ significantly.

  Emulsion from under the cap of the expansion tank

• Exhaust gases entering the coolant. If the cylinder head gasket is pierced, then exhaust gases in a small amount from the cylinder block can enter the cooling system. In this case, it is enough to unscrew the cap of the radiator or expansion tank. In the event that gases enter the system in large quantities, the seething will be very active. However, if there is a little gas, then improvised means are used for diagnostics - plastic bags, balloons, condom. We will discuss the diagnostic method in detail below.
• Antifreeze gets into one of the cylinders. usually, this is due to a gasket rupture in the place between the cooling jacket channel and the combustion chamber itself. This often results in white smoke coming out of the exhaust pipe, even in warm weather. And the level of antifreeze in the tank drops. The more antifreeze gets into the cylinders, the more white vapor will come out of the exhaust pipe.
• Oil leak out from under the cylinder head. These facts can also be signs of cylinder head gasket burnout. That is, there is a rupture of its outer shell. In this case, oil streaks can be seen near the junction of the cylinder head and the BC. However, their reasons may be different.

  Foam in the expansion tank

• Significant and rapid increase in internal combustion engine temperature. This phenomenon occurs due to the fact that hot exhaust gases enter the cooling system, as a result, it does not cope with its tasks. In this case, in addition to replacing the gasket, it is also necessary to flush the cooling system. How to do it and by what means you can read separately.
• Mixing oil and antifreeze. In this case, the coolant may enter the engine compartment and mix with the oil. This is very detrimental to the internal combustion engine, since the properties of the oil are lost, and the internal combustion engine is forced to work in unsuitable conditions, which leads to serious wear. This breakdown can be diagnosed by the presence of oily stains in the expansion tank of the cooling system. To do this, open the oil filler cap and look at the inside of the cap. If there is an emulsion on its surface (it is also called “sour cream”, “mayonnaise”, and so on) of a reddish color, it means that the antifreeze has mixed with oil. This is especially true in the case when the car is not in a warm garage, but in the winter on the street. Similarly, you need to look for the presence of the mentioned emulsion on the dipstick to check the oil level.

  Wet candles

• Poor stove performance. The fact is that when the cylinder head gasket burns out, exhaust gases appear in the cooling “jacket”. As a result, the heater heat exchanger is aired, and, accordingly, its efficiency decreases. Often, the temperature of the coolant jumps sharply.
• Increase in pressure in the radiator pipes. In the event of gasket depressurization, exhaust gases will enter the cooling system through the nozzles. Accordingly, they will become very hard to the touch, this can be checked simply by hand.
• The appearance of significant soot on candles. In addition, they can literally be wet due to the presence of antifreeze or moisture in the cylinders.

And a clear sign of an internal combustion engine overheating is the presence of condensate on its surface. This is also an indirect sign of a cylinder head gasket burnout or a crack in the cylinder block. First of all, you need to conduct computer diagnostics of the internal combustion engine. The presence of errors will indicate the direction and possible additional breakdowns. usually, these errors are associated with problems in the ignition system.

Antifreeze in cylinder

Let's also dwell on mixing antifreeze and oil. As mentioned above, as a result of mixing them, an emulsion of a yellowish (most often) color is formed. If it appeared, then one replacement of the cylinder head gasket will not do the repair. Be sure to flush the system from this composition. Including sump and oil channels. And this can cost you additional costs, sometimes comparable to a major overhaul of an internal combustion engine.

We figured out the symptoms that occur when a cylinder head gasket is broken. then let's move on to considering the reasons why it can burn out.

Why does it pierce the cylinder head gasket

In most cases, the reason why there are problems with the cylinder head gasket is a commonplace overheat. Because of it, the cover of the block can “lead”, and the plane along which the gasket is adjacent to two contacting surfaces will be violated. As a result, there is a depressurization of the internal cavity with all the ensuing consequences. Change their geometry, mainly aluminum heads. Cast iron is not subject to such malfunctions, they are more likely to crack than bend, and even then in the most extreme cases.

Scheme of drawing cylinder head bolts on VAZs "classic"

also, due to overheating, the gasket can heat up to such temperatures at which it changes its geometry. Naturally, in this case, depressurization will also occur. This is especially true for iron-asbestos gaskets.

also one reason bolt torque failure. Both a very large and a small value of the moment have a detrimental effect. In the first case, the gasket may collapse, especially if it is made of low-quality materials. And in the second - to let the exhaust gases out without interfering with them. In this case, gases, together with atmospheric air, will adversely affect the material of the gasket, gradually disabling it. Ideally, the bolts should be tightened using a dynamometer showing the torque value, in addition, the sequence of their tightening should be observed. Reference information on this can be found in the manual.

usually, the tightening sequence is that the central bolts are first tightened, and then the rest diagonally. In this case, the twisting occurs in stages. namely, in VAZ cars of “classic” models the moment step is 3 kgf. That is, all the bolts in the specified sequence are tightened by 3 kgf, after which they are tightened to 6 kgf, and up to 9 ... 10 kgf.

According to statistics, in about 80% of cases when the gasket failed, the reason for this was incorrect tightening torques or non-observance of its sequence (scheme).

And the most obvious reason low quality materialfrom which the gasket is made. Everything is simple here. Try to buy products in trusted stores. When choosing, you need to be guided by the rule of the “golden mean”. Gasket, of course, is inexpensive, so you should not overpay, as well as buy frankly cheap garbage. The main thing is for you to be confident in the store where you make a purchase.

it is also possible that the head gasket just burned out from exporting the material, because everything has its own service lines.

Examples of cylinder head gasket breakdown points

also, sometimes the reasons for the operation of the gasket are problems with a violation of the combustion process of the fuel (detonation, glow ignition). Due to overheating, the cylinder head suffers greatly. Cracks may appear in it, which will also lead to depressurization of the described systems. The head is usually made of aluminium. And when heated, it expands faster than steel bolts. Therefore, the head begins to significantly put pressure on the gasket, and it experiences overload. This leads to hardening of the gasket materials, which in turn causes depressurization.

Often when a gasket fails, it burns along the edge or between the cylinders. In this case, erosion of the surface of the cylinder block and the edging itself often appears near the damage. A change in the color of the gasket material near the edging may also indicate a high temperature in the combustion chamber. To eliminate the breakdown, it is often enough to set the correct ignition angle.

It is important for the driver to understand the difference between the concepts of “breakdown” and “burnout” of the gasket. Breakdown in this case implies significant damage to the surface of the gasket or its individual elements. In the same case (and most often it happens), the driver is faced with a burnout. That is, they appear minor damage, which are sometimes even hard to find on the gasket. However, they are the cause of the above unpleasant situations.

How to find out if the cylinder head gasket is blown

To understand if the cylinder head gasket is broken, you can use one of several methods. In this case, the diagnosis is simple, and anyone, even a novice and inexperienced driver, can handle it.

To check the integrity of the gasket, do one of the following:

• With the engine running, visually inspect is there smoke coming out of the gap between the cylinder head and the BC. also listen to see if there are loud ringing sounds coming from there, which were not there before.
• Inspect the surfaces of the radiator caps and expansion tank cooling systems, as well as necks for filling oil in the internal combustion engine. To do this, you just need to unscrew them and visually inspect. If antifreeze gets into the internal combustion engine, then there will be a reddish emulsion on the oil filler cap. If the oil gets into the antifreeze, then there will be oily deposits on the radiator or expansion tank caps.

  White smoke from the exhaust pipe

• Make sure there is no white smoke coming out of the exhaust pipe. (Actually, it's steam.) If it is, it means that there is a high probability of burnout of the gasket. Especially if the exhaust smoke has a sweet smell (in case you use antifreeze as a coolant, and not ordinary water). In parallel with this, the coolant level in the radiator usually drops. This is an indirect sign of the said breakdown.
• Check if exhaust gases are entering the cooling system. This can be done in two ways - visually and with the help of improvised means. In the first case, it is enough to unscrew the cap of the radiator or expansion tank and see if there is intense seething there. However, even if there are no intense “geysers” there, you need to use improvised means. Most often, a banal condom is used for this.

How to check the cylinder head gasket with a condom

One of the effective and popular methods of testing is the method using a balloon or a condom. It is put on the neck of the expansion tank, after unscrewing the cap. The main thing is that the condom should sit tightly on the neck and ensure tightness (instead of a condom, you can use a bag or a balloon, but the diameter of the condom is usually ideal for the neck of the tank). After you put it on the tank, you need to start the internal combustion engine and let it run for several minutes at a speed of 3 ... 5 thousand revolutions per minute. Depending on the level of depressurization, the condom will fill with gases quickly or slowly. It depends on the specific situation. Be that as it may, if it began to fill with exhaust gases, this means that the cylinder head gasket is broken.

Checking the cylinder head gasket with a condom

Condom check

Checking the gasket with a bottle

also one method of how to determine if the cylinder head gasket is blown, often used on trucks. To do this, it is enough to have a small bottle of water (for example, 0,5 liters). usually, expansion tanks have a breather (a tube that maintains the same pressure as atmospheric pressure in a closed container). The method is very simple. With the engine running, you need to place the end of the breather in a container of water. If the gasket is broken, then air bubbles will begin to come out of the tube. If they are not there, then everything is in order with the gasket. If at the same time coolant began to appear from the breather, this also means that everything is in order with the gasket.

Checking the cylinder head gasket on trucks

Checking with a bottle

The two methods described above are suitable for diagnosing a breakdown when exhaust gases break through into the cooling jacket. These methods are very effective and have been used by motorists for decades.

What to do if the cylinder head gasket is pierced

Many drivers are interested in the question, Can you drive with a blown head gasket?? The answer is simple - it is possible, but undesirable, and only for short distances, namely, to a garage or car service for repairs. Otherwise, the consequences of what pierced the cylinder head gasket can be the most deplorable.

If, as a result of the diagnostics, it turned out that the gasket was broken, then nothing can be done about it, except to replace it. it is also worth examining the adjacent surfaces, and most importantly, try to find out the true cause of the burnout ... The price of the gasket may be different and depends on the brand of the car and the manufacturer of the spare part itself. However, compared to other nodes, it is low. Repair work can cost you a little more than just buying a gasket. The point is to keep the following things in mind:

• If, during the dismantling of the cylinder head, it is found that the mounting bolts “led” and they do not meet the technical parameters, they will need to be replaced. And sometimes there are situations when, due to a change in the geometry of the cylinder head, the bolt cannot be unscrewed, and it simply has to be torn off. To carry out this unpleasant procedure, there is appropriate equipment. Often on modern ICEs, bolts are installed that operate at their yield limit. And this means that after removing the cylinder head (to replace the gasket or for other reasons), you need to buy and install similar new ones.
• If the plane of the cylinder head is broken, then it will need to be polished. For this, special machines are used, the work on which will also cost money. However, the working plane of the cylinder head “leads” not so often, but it’s still worth checking this parameter. If the surface has been polished, then a new gasket must be purchased, taking into account the thickness of the removed metal layer.

Before replacing the gasket yourself, you need to clean the head from soot, scale and pieces of the old gasket. Next, you need to revise its surface. To do this, use a special measuring tool, usually a ruler. It is carried out over the surface, revealing the presence of gaps. The size of the gaps should not be more than 0,5 ... 1 mm. Otherwise, the surface of the head must be ground or completely replaced with a new one. Instead of a ruler, you can use a thick sheet of glass (for example, 5 mm thick). It is placed on top of the surface of the head and looked for the presence of possible air spots. To do this, you can slightly grease the surface of the head with oil.

Cylinder head surface check

When replacing the gasket, it is recommended to lubricate its surface with graphite grease. So it will become softer and easier to find “its” place on the surface of the cylinder head. In addition, when dismantled, it will be easier to remove. The advantage of graphite grease in this case is that graphite is not squeezed out during operation, turning into ash.

After repair work, a car enthusiast must monitor the behavior of the motor. Do the breakdowns described above appear again (white smoke from the exhaust pipe, emulsion or greasy spots in the coolant, oil at the junction of the cylinder head and BC, there is no overheating of the internal combustion engine, and so on). And immediately after the replacement, you should not operate the internal combustion engine at maximum power. Better, in order for the gasket to “settle” and take its place.

What is the best gasket material

Gaskets from different materials

When replacing a gasket, many car owners have a reasonable question, which gasket is better - made of metal or paronite? Each of these materials has its own advantages and disadvantages. At the same time, you need to understand that if the manufacturer recommends the use of gaskets from a certain material, then these requirements must be followed.

typically, a metal gasket is stronger than its paronite counterpart. Therefore, it is advisable to put it on powerful turbocharged or forced engines. If you do not plan to tune the engine of your car, but simply operate it in a gentle mode, then the choice of material does not matter much to you. Accordingly, a paronite gasket is also quite suitable. Moreover, this material is more flexible, and is able to adhere more closely to work surfaces.

also, when choosing, it must be taken into account that the material from which the gasket is made does not have a primary impact on its service life. A much more important indicator is how the gasket was installed. The fact is that there are very thin walls between individual groups of holes. Therefore, if the gasket is not installed exactly on the seat, then there is a high probability of burnout even for the strongest material.

The most obvious sign that the gasket was installed incorrectly is its rapid failure. also, if you installed it incorrectly, the car may simply not start. In diesel engines, the sound of pistons can also be heard. This is due to the fact that the piston touches the edge of the gasket.

Hack and predictor Aviator

If you have a broken cylinder head gasket, then it is undesirable to drive a broken car. Therefore, we recommend that you replace the gasket immediately if it is found to be broken. In addition, it is important not only to discover the very fact that it is broken, but also the reason for this. namely, why the internal combustion engine overheats or other breakdowns appear.

During the replacement process, check the torque value on the mounting bolts. Timely replacement of the cylinder head gasket will save you from large financial expenses for the repair of more expensive components. The longer you drive a car with a blown cylinder head gasket, the more likely it is that other, more expensive and important internal combustion engine components will fail.