What to do if there is a decrease or absence of compression in the engine cylinders?

Compression in an internal combustion engine (ICE) is an increase in air pressure in the cylinder during the compression stroke , that is, when the piston moves up to top dead center (TDC). If there is no compression in the cylinders or it is close to a critical value, many problems arise that make the operation of the power unit difficult, and sometimes make it impossible. Loss of power, excessive consumption of fuel and oil, difficult starting, misfiring - these are symptoms that directly indicate depressurization of one or more cylinders. In the article we will tell you how to increase the service life of the engine, when and how to carry out diagnostics.

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Signs of decreased or lack of compression in the cylinders

List of possible “symptoms” of lack of compression in one, two or all cylinders of the internal combustion engine (internal combustion engine) of a vehicle:

1. A malfunction of a diesel or gasoline engine, in which the power unit stops “pulling” - it does not start or starts with difficulty. The engine can be started by cranking the crankshaft for a long time using the starter mechanism. The inability to start is due to the fact that one of the cylinders (or all at once) has low pressure or it is zero.
2. Engine operation has become unstable. The revolutions of the power unit float when idling, and while driving at speed they will be unstable. Different compression leads to a loss of normal power or to the fact that this parameter is completely absent after overheating or when cold.
3. Increased fuel consumption.
4. Problems with the cylinders. If the compression is bad and continues to fall, when driving uphill, a knocking sound from the hydraulic compensators appears (the “clatter” of metal under the hood). This problem is especially obvious if you drive with an injector or carburetor at low speeds.
5. On diesel engines, the malfunction is accompanied by popping noises appearing in the internal combustion engine.
6. With low compression in 1, 4 or other cylinders (up to 3, 5, 6, 7, 8, 9 atm (atmospheres)), the pressure level in the cooling system lines may increase. This will cause the system to begin to squeeze out refrigerant from under the sealing components. If there is no coolant and the car has leaks, it is necessary to test the compression in the third, fourth and other cylinders.
7. The appearance of exhaust gases escaping in the engine compartment from the connection of the cylinder head (cylinder head) with the main module. This problem is usually due to damage or wear to the gasket.

Error code

It is important to know

P030X is an error code that appears when compression in one or more cylinders decreases on most modern cars.

This combination appears when there is a malfunction in the ignition system. Instead of the X symbol, the diagnostic equipment displays the number of the cylinder (for example, 10 or 16) in which the error was registered.

Video: what is the reason for the lack of compression

User Alexander Stepanov spoke about the “symptoms” and reasons why there is no compression in the engine cylinders

Does compression always indicate engine health?

Before we consider the signs and reasons why there is no compression in one or more cylinders, we will analyze whether this parameter affects the performance of the power unit. If the pressure in the lubrication system of a 406 or other engine is below normal, in practice this indicates wear of the internal combustion engine components. But it is not always the case. When mating the piston rings with the plane of the cylinders, it is the lubricating fluid that collects on the walls of the engine that plays an important role. Thanks to engine oil, the interface of the components is sealed.

When not all of the air-fuel mixture burns in the power unit, this leads to an increase in fuel consumption. If spark plugs fail, fuel will wash motor fluid from the walls of the engine, because gasoline is a good solvent. And if there is no lubricant in the system, there will be nothing to seal the combustion chamber with. Accordingly, because of this, air under pressure will begin to enter the crankcase of the power unit. This leads to the fact that in a 4-6- and 8-cylinder internal combustion engine, compression will drop sharply and disappear.

If its level is normal or higher than necessary, this will cause increased consumption of motor fluid. Due to increased compression, the rings wear out faster. And the gaps formed as a result of wear will begin to be sealed with lubricant, which is in abundance. This problem requires prompt repair. But in fact, compression does not show such a malfunction.

You will learn how to correctly perform the diagnostic procedure from the video published by the AssistanceTV channel.

Why did the compression disappear?

An increased or decreased compression ratio in two, three or one cylinder can be associated with mechanical or non-mechanical faults.

Non-mechanical damage

Such problems include mistakes made during a poorly carried out “overhaul” (overhaul of the motor). It is possible that the valve timing was adjusted incorrectly and the valve elements are not closing at the right time. During the compression stroke, due to clamped valves, the piston group does not work correctly, as a result of which compression is lost. As a result, some of the air leaves the system.

The cause of the malfunction may be due to coking and sticking of the piston rings. Such a malfunction leads to the fact that the valves, which are clamped while the engine is running, can allow gases to pass through the sealing elements. The valve stem seals work without failure, but the lubricating fluid cannot properly fill all the cracks formed in the system. As a result, the consumable material is lubricated from the walls of the motor with the remains of the combustible mixture.

Mechanical damage, wear

List of mechanical reasons why compression in the engine cylinders could critically drop or fail:

1. Broken or worn exhaust valve. Cracks form on the inlet valve, and the device itself may not adhere sufficiently to the working surface. The problem may appear suddenly; before this, incorrect pressure in the compressor does not affect the operation of the car in any way.
2. If compression drops sharply, this may be due to valve seat failure.
3. Malfunction of the camshaft associated with its assembly or overhaul. Incorrect actions during overhaul will lead to rapid wear of the unit.
4. Damage or wear to the cylinder head gasket. This problem is often a consequence of natural shock absorption or dirt getting on the surface of the sealing component.
5. Gasoline hydraulic shock.
6. Seizure of cylindrical elements associated with overheating of the power unit.
7. Worn timing belt or chain. This product belongs to the category of consumables, so it must be changed periodically. The timing chain may cause damage to the engine valves.
8. Intake valve malfunction. A
9. Clogged injectors. The problem manifests itself in the same way both hot and cold. Due to the injectors, a complete stop of the power unit is possible.
10. Failure or natural wear of the elements of the cylinder-piston group.
11. The appearance of cracks and other defects on the pistons or cylinders of the engine.
12. Wear or breakage of the inter-ring bridges of the pistons.

Let's sum it up

Taking into account the above, it becomes clear that if the compression in the cylinders has dropped not due to a burnt-out valve or problems with the gasket, then more serious engine repairs cannot be avoided.

Finally, we note that in order to avoid problems with compression on relatively “fresh” engines, it is necessary to pay attention to the quality of fuel and oil, driving style and operating conditions of the vehicle, as well as monitor the condition and performance of the power system. In other words, it is necessary to avoid active carbon formation in the cylinders, since coke and deposits often cause sticking of rings and coking of valves.

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Source

How to check the level?

To find out about small or weak compression on spark plugs in the first, second or other cylinder of the engine, you must adhere to the following rules:

• the power unit must be spun up by the starter to extremely high speeds, for this it is necessary to reduce the likelihood of energy loss;
• the procedure should not be carried out on a cold engine in order to ensure maximum coupling at temperatures closest to operating temperatures;
• You must first turn off and unscrew the spark plugs from the cylinders to prevent the formation of resistance to rotation;
• you need to turn off the fuel supply so that the engine fluid is not washed off the cylinder walls;
• It is necessary to charge the battery as much as possible to effectively spin the crankshaft.

Using a compression gauge

To check the compression level using a compression meter:

1. You need to warm up the car to operating temperature
2. Relieve the pressure level in the fuel rail. Afterwards, you need to start the power unit again.
3. The next stage of diagnosis, which will allow us to understand the cause of the drop in compression, will be the removal of the tips located on the spark plugs.
4. At the next stage, you need to check whether the compression has dropped in all four cylinders of the engine.

Table: measurement results

Oil check

The oil test is carried out using 15-20 grams of lubricant, which is poured into an incorrectly operating cylinder.

Then you need to check:

• thermal clearances of valves on each cylinder;
• motor;
• lubricant.

Then the engine is assembled and started, and the cooling system expansion tank is diagnosed.

Video: checking compression without using a compression gauge

The Secret GARAGE channel presented a video showing a way to check the pressure in the engine cylinders without using compression equipment.

Signs and causes of disappearance

There are actually quite a few signs and reasons why there is no compression in one, two or all cylinders at once. Therefore, for users of our resource, materials have been collected that can help determine a decrease in the pressure level in the system.

Signs

If a gasket burns out in the cylinder head, the tightness of the cylinder itself is immediately compromised. This can be seen if exhaust gases begin to escape through the resulting gap. At this moment, the rings become stuck, which entails increased consumption of motor fluid and gasoline. In addition, in some cases, the engine power may increase, and smoky exhaust will come out of the exhaust pipe.

Cylinder operation diagram

If your car has lost compression in all cylinders at the same time or in just one of them, then the signs may be as follows:

• the engine became much more difficult to start;
• the engine is unstable, both at idle and while driving in gear, at all speeds;
• you noticed that your “iron horse” began to consume much more fuel;
• problems also began with the cylinders;
• if your car is equipped with a diesel internal combustion engine, then while the engine is running you will hear frequent popping noises;
• The pressure in the cooling system pipes increases.

Causes

What could be the reasons? There are a lot of them, but we will look at them all:

• cracks have appeared in the exhaust valve device, as a rule, this is caused by wear of the motor;
• the exhaust valve fits very poorly, which entails leakage through the place where the valve comes into contact with the “seat”;
• the valve “seat” itself is completely destroyed or has mechanical damage;
• The cylinder head gasket has burnt out. This could happen due to wear and tear. In addition, the cause of gasket wear may be contamination on the contact surfaces of the gasket. It can also burn out as a result of engine overheating, which will subsequently lead to cracks on the block or deformation of the cylinder head or the block itself;
• due to engine overheating, cylinder scuffing may occur;
• the cylinder-piston group in your engine is worn out;
• the inter-ring bridges of the piston have failed, that is, they have collapsed;
• in addition, the reason why there is no compression in one or two cylinders may be a failure of the intake valve;
• a crack has formed in one or more cylinders or on the pistons themselves;
• carbon deposits have appeared on the oil seals and piston rings, which reduces the pressure in the system;
• there are malfunctions or malfunctions in the operation of the gas distribution system;
• broken chain or timing belt. If the timing belt or chain breaks while driving a car, this may well be the reason why the valves are bent;
• the valve has stopped closing or there is a large gap when closing it. If the gap is too large, then the valve most likely does not open enough, which may be caused by incorrect adjustment or wear of the elements. Additionally, if there is not enough air flowing to one or more of the cylinders, you will hear a knocking sound under the valve covers.

How to increase compression in cylinders yourself?

If the compression is below the normalized value, then it can be increased in several ways:

1. If the valves are incorrectly adjusted in 2 or other cylinders, then adjusting them will solve the problem of low compression. If the thermal clearances are not set to normal and the motor does not work, you will have to change the valves and grind them in.
2. A damaged cylinder head gasket must be replaced.
3. If the problem is the appearance of defects on the block head as a result of overheating, then the easiest way to increase compression is by trimming the surface of the unit. Serious defects in the body of the device can only be eliminated by replacing it.

What will you need?

To carry out decoking you will need:

• alcohol;
• kerosene;
• gloves;
• spark plug key.

Algorithm of actions

Guide to increasing compression level:

1. At the first stage, pure alcohol and kerosene are mixed in a 1:1 ratio. 50 grams of the resulting composition is poured into each engine cylinder.
2. The engine is started, the motor must warm up to operating temperature.
3. Then the high-voltage wires are disconnected and the spark plugs are unscrewed using a special wrench. A mixture of alcohol and kerosene is poured into each cylinder.
4. After adding the composition, the car must sit for at least ten hours.
5. Then approximately 20 grams of oil is poured into each cylinder and the engine is started. The engine must run for at least 20 minutes. If the deposit on the walls was not critical, then most of it will be removed.

Signs of a drop or loss of pressure

Let's look at the symptoms that can be used to determine weak and low compression in all, two or the first cylinder. If your blood pressure is low or absent, the signs are:

1. Difficulty starting the power unit. In order to start it, the driver needs to turn the starter longer. And as a result of a complete loss of pressure, the engine cannot be started at all.
2. The engine began to function less stable. Due to the drop in compression, its speed at idle and when driving in gear will be unstable.
3. Increased fuel consumption. At first glance, identifying this symptom is problematic, but if you monitor this parameter, you can calculate it.
4. Problems appear in the functioning of the cylinders. When going uphill, there is a knocking sound from the hydraulic compensators (“fingers”). This is especially obvious when driving at low speeds.
5. In a diesel engine, the problem manifests itself as popping noises.
6. The pressure in the cooling system lines may increase. As a result, antifreeze will begin to squeeze out from under the sealing elements.
7. If there is poor compression in one or more cylinders and this is due to damage to the cylinder head gasket, then the tightness of the system as a whole is compromised. By opening the hood, you can diagnose this problem by the presence of exhaust gases that exit through the gap that appears. Such a malfunction leads to stuck piston rings, which ultimately increases fuel and oil consumption. In some vehicles, this symptom is complemented by an increase in the power of the power unit and the appearance of abundant smoke from the muffler.

What could be the consequences of low or no compression?

If the pressure drop in one or more engine cylinders is critical, then the problem may be due to engine overheating. Long-term use of a machine with such a malfunction will lead to complete breakdown of the motor.

Is it possible to drive if there is no compression in one cylinder?

Operation of the vehicle if there is no compression in one or more cylinders is permitted. This problem can become critical over time, that is, the engine randomly stops during operation. Then using the machine will be, at a minimum, inconvenient.

Video: review of compression enhancement products

The video from the “Motoresurs” channel provides an overview of fluids designed to increase the level of compression in engine cylinders.

Compression is the highest level of pressure in the engine cylinders during the combustion process of the combustible mixture. If there is no compression in one cylinder or several at once, then this problem needs to be corrected urgently. What are the signs and causes of low compression? You will learn more about this here.

Compression with oil

If there is no pressure, then this is either a problem with the cylinder head, or a malfunction or natural wear of the CPG. To determine which of these two factors is the cause, you need to add oil to the combustion chambers.

If there is no compression in the 3rd cylinder or in any other, then before measuring with a compression meter, pour a little oil into the cylinder. 50 grams is enough. If compression increases after filling, then the problem is in the rings. If the pressure has not changed, then the problem is in the cylinder head. In both the first and second cases, you will need to disassemble the engine for repairs.

( 2 ratings, average 4.5 out of 5 )

Compression and compression ratio are the same thing: the first fairy tale

No not like this! Compression is the pressure in the cylinder, the compression ratio is a dimensionless parameter that describes the geometric parameters of the cylinder: it is the ratio of the total volume of the cylinder to the volume of the compression chamber (the compression chamber is the volume of space above the piston at its position at TDC (it is also called the volume of the end of compression - this is the same thing). Calling it a combustion chamber is incorrect, since fuel combustion occurs throughout the entire volume of the cylinder.) Compression depends on the compression ratio, but the compression ratio does not depend on compression! Compression also depends on a bunch of parameters: compression start pressure, valve timing adjustment, temperature at which the measurement is carried out, leaks from the combustion chamber. And leaks are determined by wear of the rings and cylinders.

“Compression” is the maximum pressure that we measure in the cylinder when the ignition is turned off.

No compression - straight to capital: the third tale

Typically, a mechanic who discovers low compression immediately declares: “The engine is worn out and needs some capital.” Is everything so clear?

Of course not! For argument's sake, we can name twenty possible reasons for decreased compression. There are problems with the gas distribution mechanism, mechanical or thermal damage to engine parts, and coking of the piston rings. And only one of them will be associated with catastrophic wear of the engine. It is important to be able to distinguish between these causes, understand the degree of their danger and know methods to combat them. But this is a topic for a separate article.

Causes of compression loss

Now let's try to find out why the pressure in one or more cylinders is lost. The causes are divided into mechanical and non-mechanical. Let's look at them separately.

Non-mechanical damage

First, let's look at the non-mechanical reasons why compression in a car engine has disappeared. These include errors made during the repair of the power unit. If you yourself or at a service station set the valve timing incorrectly, the valves will be able to close, but not at the moment when required. During the compression stroke of the cylinder they will be slightly open. As a result, some air will begin to leave the system. And the displacement will not be enough for the valves to come into contact with the pistons, which will lead to their damage.

Sometimes the problem is associated with coking, as well as stuck piston rings. Such a malfunction will cause the valves to begin to stick into the grooves. Gases will pass through them easily due to the lack of a seal. With such a malfunction, the oil scraper rings function correctly, and the engine fluid cannot fill the gaps that appear in the system, since the lubricant will be washed off the walls by the remnants of the air-fuel mixture, which has not been burned.

Mechanical damage, wear

Damaged exhaust valve

If a 4- or 8-cylinder engine is running without compression, the reasons may be mechanical. Low pressure in the engine suddenly formed due to the fact that:

1. The exhaust valve has been damaged. Cracks appear on it due to natural wear and tear of the power unit. In addition, it may not fit well enough.
2. The valve seats themselves were destroyed. Weak compression is due to the presence of mechanical damage on them.
3. Worn or burned out cylinder head gasket. This usually occurs as a result of natural depreciation. Less commonly, the reason is that contamination gets on the plane of the sealing element. Gasket burnout can occur during long-term operation of a vehicle with an overheated engine. This, in turn, will lead to the formation of cracks in the cylinder head, and the head or block itself may become deformed.
4. Mechanical faults also include cylinder scuffing. This occurs as a result of overheating.
5. Wear or damage to the cylinder-piston group.
6. Breakage or complete destruction of the inter-ring bridges of the piston elements.
7. Intake valve failure.
8. Formation of cracks and other defects directly on the pistons or cylinders.
9. The appearance of carbon deposits on rings and seals, which contributes to a drop in compression.
10. Damage and further breakage of the timing belt or chain. The timing belt is a consumable item, so it must be replaced periodically. Due to a break, the valves of the power unit may bend.

Level up on your own

Now we’ll tell you what to do to increase blood pressure. In garage conditions, it can be increased due to the formation of soot and deposits on the cylinders. All other faults can be resolved by dismantling the cylinder head and replacing damaged components. When removing the cylinder head, it will need to be bored, so it is better to entrust this process to specialists. How to increase the compression level:

1. Prepare kerosene and alcohol. It is necessary to mix 25 g of each substance in a one to one ratio. One cylinder of the power unit will require 50 g of the resulting mixture. If you need to increase the pressure in several at once, then multiply 50 g by the number of elements.
2. Start the vehicle engine. Let it warm up to operating temperature.
3. Pour about 50 g of a mixture of kerosene and alcohol into the cylinders whose compression needs to be increased. The car should sit like this for about ten hours.
4. After the time has passed, add about 20-30 grams of motor fluid and start the power unit. He needs to work for 20 minutes. With minor deposits on the engine walls, carbon deposits will be removed.

How to troubleshoot

The first thing to do is check the compression in the engine cylinders using a compression gauge. This procedure usually lasts about 45 minutes, so you should have some free time. If you do not have a special device, you can purchase it or use the services of a car repair shop. If a decrease in compression is detected, it is necessary to check the condition of the pistons, cylinders, valves and gaskets. Damaged elements need to be replaced. However, be prepared for time-consuming and expensive repairs, as replacing faulty parts requires removing them from the engine.