Burnout metal cylinder head gasket. Blog ›How to understand what struck the cylinder head gasket? Signs and reasons for the breakdown of the cylinder block gasket

Burning out the head gasket can lead to leakage and / or mixing of engine fluids and gases, as it seals the connections of the channels and combustion chambers. For example, engine oil with coolant (coolant), coolant with gases from the combustion chambers. As a result, the normal operation of the car engine is violated in almost all modes, as one of the cylinders fails.

Symptoms

If oil mixes with coolant

Part of the gasket burned between the oil channel and the coolant channel.

- At the same time, a light coating (water-in-oil emulsion) appears on the dipstick and on the oil filler plug. The amount of this emulsion may be more or less, depending on the degree of burnout of the gasket. The oil level in the pan rises. In the expansion tank of the cooling system, oil stains are possible on the surface of the coolant.

- The coolant level in the expansion tank drops without visible leakage.

- There is white smoke from the muffler with a sweet smell of antifreeze, which does not disappear after heating.

- The engine "troit", loses power and throttle response, increases fuel consumption.

- The candle in the inoperative cylinder is wet.

The malfunction is eliminated only by replacing the gasket, checking the head of the block (it may have “led” it from overheating) and polishing it, changing the oil and coolant with flushing the systems.

If coolant mixes with gases from combustion chambers

Part of the gasket burned between the coolant channel and the combustion chamber of one of the cylinders.

Depending on the degree of burning of the gasket, the symptoms may be as follows.

- Drilling of coolant from the exhaust gases and a strong, constant increase in the level in the expansion tank of the cooling system.

- Coolant leak through the cap in the expansion tank, in especially advanced cases, knocking out this cap or inflating the tank (since bursting gases create excessive pressure in the cooling system). For the same reason, the radiator, pipes, coolant pump, etc. begin to flow. The nozzles become hard; it is difficult to squeeze them by hand.

- Constant airing of the cooling system leads to the stove ceasing to work (because it is the highest point of CO and gases accumulate in it), the thermostat for no apparent reason starts to open inopportune, which causes the engine to overheat. The temperature during warming up and running jumps higher or lower.

- The engine cylinder in which such a burn-out occurred starts to work worse or fails completely, which leads to engine “triple”, a drop in power and throttle response, and an increase in fuel consumption.

You can verify the presence of gases in the coolant by putting a thin rubber glove or balloon on the neck of the expansion tank (the neck cover is removed) and starting the engine - the gases exiting the neck will inflate the glove.

The problem is treated by installing a new gasket under the block head and grinding the block head, if necessary.

Oil or coolant leakage, gas breakthrough on the sides of the engine from under the head gasket

Coolant or oil leakage can be observed by visually inspecting the engine from all sides in the area where the cylinder head is adjacent to the cylinder block. Sounds from gases escaping to the outside can be heard by listening to the engine idling. In this case, depending on the degree of burnout, a drop in the coolant level in the expansion tank and the oil level in the pan will be observed.

Reasons for the malfunction

- Engine overheating due to improperly set ignition timing (late ignition), or a malfunction in the cooling system or its fan.

- Weak or uneven tightening of the block head bolts after repair.

- Installation of the head gasket in an awkward manner during repair.

- The use of low-quality fuel.

- Low quality manufacturing repair gaskets under the head of the block.

Notes and Additions

- In addition to burnout, gaskets of the head of the “triple” block can cause engine malfunctions such as: burn-out of the valve, violation of gaps in the valve mechanism, wear of pistons and cylinders, shift of the valve timing (the timing belt jumped to a tooth or two), cracks in the head of the block or block cylinders. Cm. .

- Measurement of compression will help to identify a leaky cylinder if the gasket is damaged in the vicinity of the combustion chambers.

Faulty cylinder head gasket - A thing quite unpleasant for any driver: the consequences of such a malfunction can be the most unpredictable. Therefore, so that you do not have to do a major overhaul of the engine, you need to eliminate this trouble at an early stage. That is, you need to carefully monitor how the engine works, and the condition of this small and seemingly unimportant detail of the cylinder head. But no matter how diligently and carefully we follow the motor of the car, no matter what perfect materials the seals are made of, it can still happen that burned cylinder head gasket.

Main symptoms

In most cases, we can determine the malfunction if we noticetraces of oil leakage from under the head of the block. One cause of the malfunction may beburnout valve   though improperly tightened bolts   can also be the cause of this phenomenon. But if no traces of oil leakage are visible, then it can be difficult to figure out what the condition of the gasket is. To understand that a defect has appeared in the seal, we need to know the main symptoms of this malfunction.

Before any trip, check the oil level.  If on the probe we find a white emulsion, then the gasket is broken. Coolant entering the oil system turns into an emulsion. If we begin to notice that it is not clear where the antifreeze disappears, then we urgently need to repair the engine. Most often, replacing the gasket is sufficient. But coolant can also leak when cracks appear in the cylinder block.

Reasons for burnout gaskets

White smoke from the exhaust pipe and plaque on spark plugs is also a sign of a defect in the cylinder head. Coolant through a damaged gasket enters the cylinder and exits as a vapor from the muffler. Do not forget that a similar effect may occur if the humidity is high. Repair should be started if the steam appears even in dry weather.

About what happened burnout gaskets, evidence of oil stains on the surface of the liquid for cooling.If oil has got into the cooling system, you should immediately contact a specialist to prevent the engine from jamming.Bubbles in a radiator or expansion tank are another symptom of burnout of a car gasket, as a result of which the exhaust gases are mixed with coolant. If bubbles appear all the time, and not just during the replacement of antifreeze, then the seal must be replaced. The burning of a car gasket is evidenced by the smell of exhaust gases from the expansion tank and the unstable idling of the engine will also make us think about the condition of the oil seal and help determine the symptoms of malfunctions.

Replacement procedure

We can detect burnout of car laying during visual inspection. If the defect can be detected on time, then you can limit yourself to replacing the gasket. In general, replacing the gasket is not difficult. The main thing is to carefully unscrew the bolts securing the cylinder head. We clean the bolts from burning, remove traces of oil and dirt. Then we unscrew them half a turn each, in a certain order. It is not possible to dismantle the cylinder head with attached attachments. Therefore, we disconnect all devices, filters and belts. At the same time, we take pictures or record everything (so that there are no unnecessary details). Remove the head and replace the gasket. We install the new part in place and focus on the bushings that enter the holes in the corners. So we can’tmake a mistake and put the gasket correctly, without distortions.

Now it remains to put the cylinder head in place,  connect all attachments and tighten the bolts as described in the operating instructions. We will check the tightening torque with a torque wrench. If something does not work out, we can turn to specialists who will do everything quickly in one day.Such a service is inexpensive.

We all know that the engine is one of the most important parts of a car. Engine malfunctions cannot be compared with running gear malfunctions or electrical equipment malfunctions, although, of course, each system and part individually plays an important role. Simply, if with a faulty ball or racks you can somehow move at your own peril and risk, then with a faulty engine this is not always possible.

Today we’ll talk about such an unpleasant phenomenon as a breakdown of the cylinder head gasket. About why this happens, how to understand what has broken the cylinder head gasket, and also how to check the cylinder head gasket for breakdown.

To begin with, what is the cylinder head? A cylinder head is a cylinder head, in other words, a cover that hermetically covers combustion chambers (cylinders). The cylinder head fits snugly against the cylinder block (BC), which actually houses the cylinders in which the pistons move. Between the cylinder head and the BC is the cylinder head gasket, which serves as a sealant. In case of damage (breakdown) of this gasket in the engine, various processes begin to occur that worsen its operation and lead to its destruction.

What is the cylinder head gasket?

For each car manufacturer, this gasket can differ significantly both visually and the material from which it is made. Paranit and even thin sheet metal can serve as material for the manufacture of cylinder head gaskets. Due to the fact that the gasket walls are rather thin, breakdowns, damage and burning of the cylinder head gasket often occur, after which problems with the engine are guaranteed. Often the cause of breakdown or burnout is errors made during the installation of the cylinder head.

Signs of a broken cylinder head gasket:

Lumbago out. When exhaust comes from under the head. It is difficult not to notice, and the sound will be such that it will not be impossible to hear.

If the cylinder head gasket has broken between the cylinders, then it is rather difficult to detect such a breakdown, but it is still possible. For example, you can measure compression, which will accurately detect problems with the cylinder head gasket. In addition, the motor will work unevenly (it can troit).

Exhaust fumes in coolant. Very often, just such an anomaly may indicate a breakdown of the head gasket. However, it is impossible to say unequivocally that the reason is in the gasket, since gases in the coolant can also appear through a crack in the cylinders or the cooling jacket. In such cases, the engine will “eat up” the coolant, and the exhaust will have a strange look and smell. As a rule, in such cases, the exhaust becomes like steam, white. Also in the expansion tank there may be bubbles that smell like exhaust fumes.

Oil or water smudges on the engine. In this situation, we can precisely conclude that the cylinder head gasket is broken or the head itself is installed incorrectly.
Unreasonable increase in engine temperature. The temperature rises due to the fact that the heat from the combustion of the fuel mixture enters the cooling system, as a result of which the antifreeze is heated.

Increase engine oil level. We all know that some motors "take oil", sometimes it is even provided for by the design of the engine and is not considered a malfunction. However, there are situations when the oil does not decrease, but rather increases ... And believe me, there is very little funny. In fact, an increase in level occurs as a result of coolant entering the oil. By the way, the consequences of such a dilution can be the saddest. The oil becomes less viscous, the motor is not lubricated enough, as a result of which the frictional force between the parts increases. The wear of these parts is also increasing and it’s rather difficult to say exactly how long an engine that works almost “dry” is enough. One thing is clear - the engine will receive serious damage, and its engine life will be seriously reduced. If coolant is to be poured into oil, or vice versa, then, most likely, in the expansion tank of the coolant you will see oily spots.

Why is this happening? The cylinder head gasket has broken - the reasons

Engine overheating. As a result of overheating, the cylinder head gasket burns out. How? That's how! Metal-asbestos gasket is not able to withstand the high temperatures that are formed when the motor overheats, therefore, as soon as the temperature becomes critical, burnout or bloating of the gasket occurs. As a result, in places of burning or swelling, the gasket becomes less durable and after several heating / cooling cycles, the problem area leaks.

The second reason for the breakdown of the cylinder head gasket is the deformation of the head, more precisely the plane with which it is adjacent to the block. As a rule, aluminum heads are subject to deformation, this does not happen with cast-iron, they are more likely to have cracks. Deformation is treated by grinding on a special high-precision machine.
Bolts of fastening of a head of the block of cylinders. Incorrect tightening when one bolt is tightened and the other is weaker leads to the fact that in some places the clamping force is lost. It is in such places that gasket breakdowns occur. Tighten the cylinder head bolts with a torque wrench, observing all the rules of this procedure.

Poor quality of the cylinder head gasket itself. Everything is simple here, it happens that the owners saving, and performing engine repairs, do not put the original gaskets. As a result, after several thousand km. a breakdown of the cylinder head gasket or its burnout is quite possible.

In a car engine, the cylinder head (cylinder head) is one of the most loaded elements of the power unit, subject to a fairly strong temperature effect. And one of the important parts of the cylinder head is the gasket, which ensures tightness between the head and the cylinder block, as well as in the combustion chambers and channels of the cooling system.

What threatens the burnout of the cylinder head gasket

A breakdown of this product is a rather unpleasant and dangerous phenomenon: even a small hole or crack can lead to sad consequences; namely, engine overhaul. This will happen due to the loss of oil lubricating qualities, because it will be diluted with coolant. And this will quickly lead to premature wear of the cylinder-piston group.

What is the cylinder head gasket made of

If other components of the machine use gaskets made of special cardboard or rubber, then the head is made of a product made of special materials and having a complex shape. The material must be sufficiently strong and heat resistant. Today, all gaskets can be divided into a couple of large groups.

1. Non-metallic. There are two types: asbestos and asbestos-free. In the first case, the gasket is made of sheet material. Moreover, all openings (for cylinders and fasteners) along the edge of the cutout are reinforced with metal rings. Gaskets made of pressed rubber with the addition of graphite powder and asbestos fibers are also produced. You can do without the latter: in this case, synthetics and rubber are pressed, pressed at high temperature. Such gaskets are slightly more expensive than those discussed above, but they have increased wear resistance.
2. Metal. They are considered the most common. The material for their manufacture is sheet copper (an expensive option), or thin sheet steel. To achieve better sealing, areas in contact with the planes of the cylinder head and cylinder block are coated with a composition of special rubber. Metal gaskets have a longer service life compared to asbestos. However, defects can appear in both types of products.

Causes of gasket damage

Most often, this is the continuous operation of the power unit at the limit of its capabilities, which causes the motor to overheat and deform (sometimes break) the gasket. There are other reasons, among which it is worth noting:

• inappropriate fuel quality;
• excessive compression of the mixture;
• incorrect adjustment of the ignition system (candles have the wrong glow number);
• loose tightening of fixing bolts.

Symptoms of burnout cylinder head gaskets

What are the main signs of breakdown?

Foam

It appears on the dipstick, which serves to control the oil level in the crankcase, as well as on the filler neck. It also happens that during the examination it turns out that the gasket is intact: it means that the reason is the appearance of a crack in the cylinder block itself.

White smoke

It appears from the muffler when the engine is operating in any modes (with a whole laying during the warming up of the car in winter, there will also be a bright exhaust, but this is normal). A similar phenomenon indicates that coolant has penetrated into the cylinders of the power unit. You can verify this if you check its level in the tank: the amount of antifreeze will be less than what is prescribed by the instructions.

They can be seen on the surface of the antifreeze in the radiator or tank. It is clear that fuel and lubricants should not be in the cooling system. Also pay attention to the possible appearance of air bubbles in the same tank or radiator. Their presence indicates the penetration of exhaust gases into the coolant. But here it is necessary to remember: a small number of bubbles can form during the usual replacement of antifreeze, but if it constantly “bubbles”, then there is reason to think about the integrity of the cylinder head gasket.

Exhaust gas breakthrough

You can also note another reason for the lack of tightness between the block and the head. This is an incorrect tightening of the fasteners. It must be carried out in the strict manner described in the instructions for the car. It is possible to determine that the sealing element is damaged due to the penetration of gases into the coolant after removing the gasket - through the destroyed jumpers located between the holes for the cylinders.

How to replace the cylinder head gasket

The work algorithm is basically the same on all cars. The difference is only in the order of tightening the bolts and the value of the tightening torque (for this you will need a torque wrench). These parameters are usually indicated in the vehicle's operating instructions. First remove all optional equipment secured to the cylinder head. Next, remove the valve cover and camshaft.

Having gained access to the bolts securing the head, carefully wipe their threads - otherwise, due to dirt, the nut will go tight, which can lead to a breakdown of the key (the edges of the hardware will be damaged) or damage to the thread. Unscrew the fasteners, starting from the middle. In this case, at the initial stage, evenly loosen all fasteners by 0.5-1 turns.

When the fasteners are removed, dismantle the cylinder head and install a new gasket: it is centered by means of special bushings mounted on the block. Assemble in the reverse order. Tighten the fasteners in the order and with such effort as prescribed by the manufacturer.

ALEXANDER KHRULEV, "ABS"

The requirements for gasket materials and their production technologies are very high and increase along with an increase in engine power.

The essence of all gasket defects encountered in practice is in the very scheme of sealing the junction of the block with the cylinder head. Indeed, the gasket must simultaneously provide gas seal (cylinder cavity), water seal (channels of the cooling system) and oil (channels of the oil system). The close arrangement of these channels and cavities to each other, obviously, can lead to internal leakage. But external leakage is also not a gift.

The cylinder head gasket can lose its tightness for many reasons. But the main ones still remain violations of the rules of operation, technology of maintenance and repair of the car. It is equally important to note that the external manifestations of cylinder head gasket malfunctions are also very diverse. You can even say that one individual symptom rarely appears independently of the other. But, taken together, they allow you to diagnose and accurately determine the cause of the malfunction.

Of course, for the correct diagnosis, the experience and knowledge of the engine, including the design and working processes occurring inside it, are necessary. And then the truth will be established on the traces of oil or coolant, discoloration of liquids or parts, deposits of carbon deposits, traces of compression, burning or erosion on the surface of the parts.

Gasket defects after long-term operation of the car are most often associated with not noticed and not resolved malfunctions of the cooling system in time, less often - with violations of the combustion process (detonation, ignition ignition). On the contrary, after engine repair, according to statistics, in more than 80% of cases, the gasket is damaged due to improper bolt tightening (including due to non-observance of the torque and tightening order).

Overheating is one of the main causes of damage to gaskets. And not only them: during overheating, the plane of the head, and sometimes the cylinder block, is often deformed.

But first of all, of course, the block head suffers. In addition to local overheating of individual sections of the combustion chambers, causing cracks, the general heating of the head leads to an increase in the compression force of the gasket, since the aluminum alloy of the head expands more than steel bolts. After cooling, the compressed gasket may no longer provide tightness where the specific pressure (force related to surface area) is too low. In fact, when overheating, a kind of "hardening" of the surface layers of the gasket occurs, as a result of which it loses its elasticity and can no longer provide a seal for the connection of the head with the cylinder block over the entire plane.

Detect the cause, i.e. to establish that the gasket "leaked" due to overheating of the engine, it is possible during its inspection. Usually in such cases, the surface of the gasket becomes hard, and in some places near the combustion chambers it becomes carbonized.

Repair in this case is rarely limited to just replacing the gasket. In addition to processing the plane of the head, it will not be out of place to find the cause of overheating in the cooling system - there may be a malfunction in the thermostat, fan, or simply leaking hoses.

But, let's say the engine was very overheated, and the gasket seemed to resist. In such situations, there are two ways out: either try your luck, waiting for a leak to appear (and it will most likely be so), or replace the gasket right away. The second solution will be more successful: after all, whatever one may say, the planned repair is better than an unexpected breakdown on the road.

If the gasket is not crimped as it should, then it will definitely “leak”. This usually happens when the head bolts are not tightened properly. But such errors today are more an exception than a rule: now the necessary information is available at any service station. Another thing is when everything is tightened correctly, and the gasket is not crimped. What's the matter?

The reasons usually lie in violations of basic repair technologies. For example, repair manuals write that the threaded part of the bolts must be lubricated with oil before tightening.

And if you do not lubricate? Then the tightening torque will be spent almost all on overcoming the friction forces in the thread, and not at all on pressing the head to the block.

Maybe this is one of the reasons that on some modern engines the threaded part of the bolts is coated? These bolts do not need to be lubricated. But seriously, the “solid” lubricant is much more efficient and significantly improves the operation of the bolts (recall that with ordinary bolts only 20-25% of the torque is directly converted to a tightening force).

Even worse, when the bolts are too plentifully doused with oil. In this case, the well-known rule “you won’t spoil the porridge with oil” will not work: the oil is incompressible, filling the threaded hole, it simply will not let the bolt go further. And it’s good if the block does not crack through the threaded holes.

Modern engines often use yield strength bolts. After a single use, they are supposed to be replaced with new ones, since they can be unacceptably stretched.

That the gasket has not been crimped properly is easy to detect when inspected. Often, there are practically no signs of compression on it, and the thickness remains the same as the new gasket. In such cases, a leak appears in the very first hours of engine operation, which indicates the true cause of the malfunction.

Prevention is simple: it is necessary to precisely follow all the manufacturers' recommendations on the torque, tightening order and bolt replacement, as well as their lubrication before assembly.

It is known that, depending on the material and construction, the gaskets can “weaken” under the influence of temperature and vibration. And if after some time the engine does not retighten the bolts, the specific pressure at the junction of the head with the block may unacceptably decrease, after which the gasket will “leak”.

Not all engines and not all gaskets require retightening. But when such recommendations are made by the engine manufacturer, they must be strictly observed. If this is not done, a leak will appear after several thousand kilometers of the car’s run, which will directly indicate the cause of such a malfunction.

To violations of the combustion process in the engine include detonation and ignition ignition. Without going into their nature (this is a topic for another discussion), we point out that these phenomena cause a significant increase in temperature in individual sections of the combustion chamber. Excessive pressure in the cylinder due to premature ignition of the fuel mixture dramatically increases the load on the head of the block, "stretching" the bolts and thereby reducing the compression force of the gasket. And the shock waves of detonation "knock" not only on the ears of the driver, but also on the edging of the cylinder head gasket.

The fact that it was a violation of the combustion process that caused damage to the gasket can often be established by its appearance. In such cases, it often burns out between the cylinders. Burnout along the edging is often accompanied by erosion of the surface of the block head and the edging itself near the damage. A change in the color of the gasket material near the edging can also indicate a high temperature in the combustion chamber.

It is not difficult to eliminate the causes of damage to the gasket. It is enough to set the correct ignition timing, put the spark plugs required for a given engine and pour gasoline with the appropriate octane rating into the tank. True, in some cases this may not be enough.

Mechanical problems. As you know, the cylinder head gasket is a very delicate part that is easily damaged by careless handling. If it has obvious defects, then putting it is either dangerous or simply pointless - it will "flow" sooner or later.

The same applies to attempts to reuse an old gasket. Its material is already crimped and will never provide a reliable seal. It may be enough for several thousand kilometers, but this can only be regarded as a temporary way out. Sometimes burnout gaskets occur due to the ingress of foreign materials between it and the sealing surface. This can happen if you do not clean the plane of the head and block from the remnants of the old gasket before installing a new one.

By the way, the same thing will happen if the planes turn out to be deformed - in places of "failures" the specific pressure will be unacceptably low, and in the end the seal will break. Therefore, before installing the gasket, checking the planes of the head and block is mandatory (see "ABS-Auto", N 4, 1998).

It is clear that the deformed plane must be processed, i.e. align. In some workshops, the heads are milled, in others they are ground, and in others they are ground on a plate with abrasive paste. And which way is better?