The occurrence of piston rings: signs, causes and how to eliminate. Engine piston rings

07.08.2023

Oil scraper rings prevent oil from penetrating the crankcase into the combustion chamber by removing excess oil from the cylinder wall. They are installed below compression. They, unlike compression rings, have through slots or consist of two scraper-type rings. On the pistons of some engines, composite oil scraper rings are installed, made of two steel disks and two spring expanders - axial and radial. An axial expander located between the discs presses them tightly against the walls of the piston groove. The radial expander presses the discs tightly against the cylinder. The collection rings adhere well to the cylinder surface and ensure low crankcase oil consumption.

Main functions and types

The oil scraper rings are installed at a level lower than the compression rings. In contrast to the one-piece structure of compression, they are made with through slots (made of cast iron), or composite with expanding springs (made of steel). Composite rings are one thin upper ring, one lower and two expanders (axial and radial). Depending on the type of piston and engine, a pair of oil scraper rings can be installed. This type of rings is produced in three types:
- chrome-plated,
- non-chrome-plated,
- steel.

Sealing the expansion or combustion chamber; increase in compression, so that the engine can run and start. Reducing the overall consumption of engine oil of the machine (for all four-stroke and diesel two-stroke engines); this must ensure sufficient lubrication of all sliding elements. Keeping exhaust gases from getting into the crankcase. Removal of excess heat from the working piston, which prevents its overheating and normalizes heat transfer through the cylinder walls.

Ring design

Before considering malfunctions and finding out when replacement or decoking of oil scraper rings is required, you need to find out their design features. One-piece parts are no longer produced today, as they are already unpopular. Such parts have increased rigidity, which is why they do not fit well to the surface and do not remove oil well. Today, parts are produced that include two or three parts. Such parts are called "stacked oil scraper rings".

The first option consists of the oil scraper ring itself and the coil spring. The advantages of such a product: it is quite flexible, which is why it fits snugly against the walls of the cylinder. The spring is pressed against the ring so hard that the part looks solid. Three-piece rings consist of the following elements: a spacer spring and two steel plates. They are usually used in cars with gasoline engines. The advantage of this design is that it fits as tightly as possible to the cylinder.

Signs of wear rings and their diagnosis

You can find out when oil scraper rings need repair or replacement by some factors: oil consumption in the engine has become much higher; at the beginning of the movement or after a short stop - the appearance of blue smoke; leakage and evaporation of oil in caps, seals, etc.; the color of the leaking liquid also matters: if it is dark, then the seals must be replaced; the next step is to check the candles, if they are dirty, then you need to contact a car service or repair it yourself. If you find any signs of wear, first of all, you need to pay attention to the oil scraper rings. Checking the caps is pretty easy. It is necessary to remove the ventilation hose, if the pressure in the crankcase is high, then the caps are out of order.

What to do when the rings are worn?

In order to choose a way to solve the problem, you need to find out why it arose. The occurrence of the above symptoms may be caused by wear or breakage of compression and oil scraper rings, or if they are coked and stuck.

In the first case, it will be necessary to disassemble the engine and install new parts instead of damaged ones. In this case, all mating parts should be carefully inspected, since if the rings break, scoring may occur, which can only be eliminated by overhaul.

If there is an assumption that the piston and oil scraper rings are stuck, then a special additive can be added to the oil. But this method is used, as a rule, for preventive purposes.

Piston ring-related malfunctions occur quite often in practice. Therefore, in order to prevent the occurrence of serious consequences and, as a result, high repair costs, it is necessary to recognize their first symptoms in time and take appropriate measures.

FEATURES OF INSTALLATION OF OIL RINGS

I want to draw your attention to the installation of oil scraper rings. There should be no problems with compression if you follow simple rules, install with the inscriptions up (inscriptions, dot) and use a special tool.

When installing oil scrapers, difficulties may arise if there are no inscriptions, or the correct installation of the expander lock. Let's look into this in more detail. If there are no inscriptions, then it does not matter which side you put the ring on and which one will be on top and which one will be on the bottom (type-setting).

Often errors occur when installing a piston in a cylinder, even if a special clamp is used to tighten the rings on the piston. The feature is as follows. When assembling the oil scraper ring, you should pay attention to the expander lock and the correctness of its docking. For clarity, see the image below.

During the compression of the rings on the piston, the oil ring expander lock may come off the correct position and lie in an overlap gathering in a spiral, so the plates fall through the expander and this will lead to scuffing of the cylinder walls and piston grooves. To avoid this, the tightening collar should be positioned in such a way as shown in the image.

Differences between oil scraper rings and caps

Inexperienced car owners often confuse oil scraper rings with valve stem seals. In fact, these two elements perform the same most important job in the engine - they protect the combustion chamber from excess oil. The valve stem seals themselves, or as they are also called valve seals, are located in the cylinder head and mounted on the valve bushings. Their task is to remove oil from the valve stems from the top of the block head. Oil scraper caps Oil scraper rings are a part of piston rings and are established on the pistons which are in the block of cylinders of the engine. Malfunctions When both oil scraper rings and valve seals are worn, increased engine oil burnout begins, the temperature rises and there are interruptions in the operation of the power plant. This is expressed in such malfunctions as: unstable starting of the motor; interruptions in the operation of the cylinders; increase in engine temperature; decrease in dynamics and power; increase in fuel consumption.

What to do if oil scraper rings lie?

The occurrence of piston rings leads to a loss of their mobility. This happens due to the accumulation of soot from burnt oil, which greatly clogs the grooves in the piston, which leads to sticking of the rings inside the “nests”. In this case, the seals between the piston and the cylinder are bound to deteriorate. The engine loses compression without developing the required power, since there is not a sufficient degree of compression of the working mixture. By the way, it is for the same reason that the engine will not adequately start in cold weather, since the rings are clogged with coke.

What follows next? The first thing that will indicate problems with the engine is increased oil consumption. Oil scraper rings suffer from soot, as they work like a scraper. Often, piston ring sticking occurs during short trips within the city, when the engine does not have time to warm up.

Another reason for the occurrence of rings is low-grade (fake) oil. The quality of the oil is a very important aspect, since there will be soot or not - it depends on the quality of the product. So, for example, if you use questionable butter, it will burn like margarine in a pan. Therefore, buy the oil that is recommended specifically for your car by the manufacturer.

The cost of replacing rings and caps

The work of replacing piston rings costs differently at bus stations and averages from 8,000 to 10,000 rubles or more, depending on the design of the engine and the complexity of the work, as well as the make of the car.

To replace the caps, the cost of work starts on average from 3,000 rubles.

A good car can cover hundreds of thousands of kilometers without any complaints, if you follow it, regularly change consumables and repair parts that are close to failure in time. The engine does not have a specific service life, but after 150,000 kilometers, most engines have various serious problems. One of these problems is the occurrence of piston rings. If it is noticed and eliminated in time, you can save the engine from the need for major repairs.

Table of contents:

Why piston rings are needed

Pistons are key elements in internal combustion engines. They must be kept lubricated so that they can operate normally without overheating or chafing. In this case, the oil should not enter the combustion chamber, otherwise carbon deposits will occur, which will lead to a deterioration in engine performance.

Piston rings are open. They are put on the piston and come in two types - compression and oil scraper. On modern pistons, most often the distribution of rings is as follows: 2 compression and 1 oil scraper.

The purpose of the compression rings is to pressurize the combustion chamber. There is a small gap between the pistons and cylinders, due to which it is not possible to create the necessary pressure in the combustion chamber. If there were no rings, gases from the combustion chamber would go into the crankcase through the gap. The rings are made open so that they can be compressed and unclenched within the limits predetermined by the designers, maintaining the required pressure.

At the same time, the very presence of compression rings does not completely eliminate the problem with the penetration of exhaust gases into the crankcase. To avoid this, designers use a number of other tricks, at a minimum, breaks in open compression rings are positioned so that they are 180 degrees relative to each other.

Why piston rings stick

The main reason for the occurrence of piston rings is the formation of a large amount of carbon deposits on the engine elements. There are 4 main reasons for this:

To avoid the occurrence of piston rings, it is necessary to exclude the formation of carbon deposits on the engine elements as much as possible.

Signs of the occurrence of piston rings

Symptoms of the occurrence of compression and oil scraper rings are as follows:

From the exhaust pipe of the car comes out;
Decreased;
The car began to pick up speed more slowly due to a deterioration in the quality of the engine;
The motor starts worse in the cold season.

In especially neglected situations, it can smell burning in the cabin when the engine is running.

How to get rid of the occurrence of piston rings

We recommend reading:

To eliminate the occurrence of piston rings, it is necessary to perform decoking of the engine. This procedure can help if the problem is not running, and the resulting carbon deposits have not caused damage to the piston or combustion chamber. In fact, the decarbonization procedure allows you to remove carbon deposits from engine elements, including piston rings.

Engine decoking is performed as follows:

Decoking will remove the resulting carbon deposits and eliminate the occurrence of piston rings. For decoking, you can use both specialized tools and "folk" options, such as kerosene and a mixture of kerosene and acetone.

Oil scraper rings are one of the most important elements of the engine. What are these details, where they are installed and how to replace them - every car owner must know in order to help his iron friend at any time.

What are these details

Oil scraper rings are part of the piston rings and play an important role in the operation of the car. This part consists of an upper compression, compression and oil scraper and a lower oil scraper ring. It is on their work that the following parameters depend: the amount of accelerating power, how toxic the exhaust gases are, starting the engine and the amount of fuel and oil consumption. That is why it is so important to keep track of their technical condition.

Functions of oil scraper rings

The main function of such rings is to remove heat from the piston. Otherwise, it threatens the piston with various defects - for example, burnouts or scuffs, which leads to a malfunction of the spare part and the entire mechanism as a whole. As a result, the part will jam in the cylinder. Also, it is the oil scraper rings that are responsible for how tight the combustion chamber is, which means that they minimize the ingress of gases from the crankcase into the cylinder and back. In addition, there is an adjustment of how the mating elements are lubricated. It is important to remember here that both too little oil and too much oil can damage the engine.

Ring design

Today, parts are produced that include two or three parts. Such parts are called "oil scraper rings".

Operation of the compression ring

The compression ring has the most load, therefore, special alloyed materials are used in its manufacture. Its surface is covered with a wear-resistant substance so that the ring can withstand the pressure of gases and high temperatures. As the ring approaches top dead center, there is less lubrication, and the increasing pressure in the cylinder ensures that the ring seals more tightly against the cylinder. In this case, there is also a decrease in the speed of movement, and at a complete stop, an oily film may break. In this case, the compression ring undergoes dry friction during operation, and hence its rapid wear.

The work of the middle and most oil scraper ring

On the middle ring, the load is much less. In its production, alloyed cast iron is used. On forced engines, the compression-oil scraper ring is covered with a wear-resistant material. This is because the pressure remains high at the lock. By the name of this ring, you can guess that it performs both compression work and is involved in lubrication. To prevent oil from entering the combustion chamber, the cone angle of the outer surface is no more than 80 g. The main task of the compression oil scraper rings is to remove oil from the cylinder and prevent it from entering the combustion chamber.

The oil scraper rings themselves perform only one function: they remove oil and divert it to the crankcase. For the highest quality performance of this task, the design provides for two belts, and each of them is engaged in removing oil residues. As a result, the collection of liquid occurs between the belts and at the bottom of the part. To eliminate it, there are special caps with oblong slots through which liquid is removed. Then it flows into the sump or remains on the outside of the piston.

Checking the condition of oil scraper rings

It is not easy for piston caps and oil scraper rings to work, so no one cancels natural wear. Typically, this kit runs about 150 thousand kilometers, and in some cases twice as much. But to achieve such indicators is possible only when the correct operation of the vehicle is carried out. In most cases, the engine will have to be repaired earlier. Frequent replacement of oil scraper rings may be due to the following factors: low-quality or unsuitable oil, its untimely replacement. It is also important to keep an eye on the air filter, especially if dusty areas are a frequent route. In addition, the fuel filter must be in good condition.

Overheating or heavy load of the engine itself is also undesirable. In this case, carbon deposits form in the piston grooves. If the oil scraper rings are stuck, the piston will not fit snug enough against the cylinder. This significantly reduces the power of the car engine. In order for the oil scraper rings to last as long as possible, some rules must be followed. Short trips in winter are dangerous for the engine, as it does not warm up to the optimum temperature. Also, in winter, you should not overload it, due to insufficient lubrication, overheating may occur. As a result of this, jamming and the formation of defects on the walls of the cylinder and piston occur. In this case, there is a complete wear of the caps and partitions between the grooves. Unfavorable for cars and constant city traffic jams.

Signs of wear rings and their diagnosis

You can find out when oil scraper rings need repair or replacement by some factors:

the oil consumption in the engine has become much higher;
at the beginning of the movement or after a short stop - the appearance of blue smoke;
leakage and evaporation of oil in caps, seals, etc.;
the color of the leaking liquid also matters: if it is dark, then the seals must be replaced;
the next step is to check the candles, if they are dirty, then you need to contact a car service or repair it yourself.

If you find any signs of wear, first of all, you need to pay attention to the oil scraper rings. Checking the caps is pretty easy. It is necessary to remove the ventilation hose, if the pressure in the crankcase is high, then the caps are out of order.

Decoking of oil scraper rings

Not all parts need to be completely replaced. If there is soot or rings are buried, then decarbonization will help. There is the following recipe to restore these elements without disassembling the engine. It is necessary to prepare a mixture, which includes acetone and kerosene in equal proportions. After that, the spark plugs are unscrewed, and the prepared mixture is poured into the cylinder through the holes. You have to wait 9 hours. After this time, we screw the candles into place, start the engine and drive at high speeds. After that, it is recommended to change the engine oil and filter.

A special decarbonizer can also be bought at the store. In principle, it turns out the same thing, but you need to read the instructions. The decarbonizer is also poured into the candle holes, only it takes less time to deoxidize the carbon deposits - as a rule, 15 minutes, but this needs to be clarified in the instructions.

Replacement Parts

Decarbonizing can only help with soot, but if the parts are worn out, then they only need to be changed. Replacing rings and valve stem seals can be done with your own hands. It is produced using a special puller, a mandrel for pressing, a metal rod, you will also need tweezers and a cracker. When buying new caps and rings, it is best to give preference to original parts, because fakes will not last long. Moreover, the coating material of the upper rings should ideally match the material of the engine.

First you need to remove all components and mechanisms in order to get to the details. The air filter is removed first, then the fuel pump and ignition distributor. To dismantle the drive housing of the auxiliary elements, we disconnect the bolted connection. Then comes the removal of the negative terminal and the toothed pulley. To release the block head cover, remove the mass drive. Now we unscrew the nuts of the front and rear camshaft bearing housings.

Remove the camshaft key and take out the seal. We set the piston to TDC, take out the candle, insert the rod into the hole so that the valve does not fall out, after that you need to compress the springs and remove two crackers, press out the rings.

Installing new parts in place occurs in exactly the reverse order. Oil scraper rings of VAZ models change in the same sequence.

For novice motorists, this is just some kind of set of words: piston compression rings. To make it clearer, let's first understand what this mechanism is.

The purpose of the compression ring in the piston assembly of a car

This uncomplicated product is an open circle, which has a small gap (in size it can reach several hundredths of a millimeter). The ring is planted in a piston engine, be it internal combustion or steam. Regardless of where it is used, it performs three main functions. Firstly, it perfectly seals the combustion chambers. Secondly, it is a heat transmitter through the cylinder walls - it filters heat from the piston and prevents overheating. Thirdly, it would seem that such a simple element, but it also perfectly reduces the consumption of engine oil, if, of course, one is used.

As you can see, the functions are important, so at this point in time it is impossible to imagine an engine without a piston ring. Let's analyze the device of our element in more detail. Regardless of the type, everyone has a lock, it is a joint between the end of our ring, which is compressed to a few hundredths of a millimeter when the piston enters the cylinder. Compression rings serve to seal the chamber in order to create the desired. Most often, their cross section has a rectangular shape, and at the very edge it has a cylindrical profile. During operation, it can slightly twist, thereby fitting the running-in.

Compression and oil scraper rings - what's the difference?

Piston rings are divided into compression and oil scraper. Oil scraper rings are not used everywhere. For example, in gasoline two-stroke engines, this part does not make sense, since the oil burns out along with the fuel. After all, the main function of the oil scraper ring is to remove excess. These small parts are available in two different types: cast iron (cast with a slot) and steel (compound using expander springs).

The compression ring must prevent the passage of excess liquid and air into the combustion chamber.

We smoothly move on to the principle of operation of compression types of rings. To create a reliable piston that will be of high quality and efficient operation, it is necessary to use narrow piston rings. It is worth noting that in the free state the ring has a larger diameter and goes at an angle from the lock outwards. It is this design that allows, after the ring is installed, to press more tightly against the walls. This increases the efficiency of our part.

The ring is also actively pressed by the force of the working gas and liquid during engine operation. They penetrate into the piston grooves gradually with pressure, which in turn is many times greater than the force of the ring tension. They push it out of the groove and thereby, accordingly, minimize any kind of attempts by working gases to fill the crank chamber.

How can a piston compression ring fail?

For stable operation of the engine, one ring is enough. For example, on scooters or motorcycles with a weak engine, a piston with a single ring is installed. But if you do not take into account the scooter engine, then some devices have pistons with a loaded working part, where 5 rings or even more can be used on the piston.

Like any part of a car, piston rings can break or be damaged in some way during an accident or other physical impact on the car. Most often, pistons break from a large number of high loads during operation.

During the fracture test, you will be able to observe raster lines on the surface of the impact site, which can allow you to identify damage and give an assessment of the general condition of the piston. When the piston wears, thermal stress cracks can also be observed. As a rule, they are located at the bottom of the piston and, of course, it will be much more difficult to see them.

When choosing a used car, it is very important to make sure that it is in good condition. It is necessary to responsibly check the performance of all details in order to avoid trouble in the future. Particular attention is paid to the engine, as it is the most important component of the car. One of its main parts are oil scraper rings. Next, we will consider what they are for, and what to look for when buying a car.

Purpose of oil scraper piston rings

Piston rings consist of three elements:

top compression ring;
compression oil scraper ring;
bottom oil ring.

There are only two components: one ring and a spring.

These parts are installed on the top of the piston, and perform the following tasks:

prevent overheating of the piston, removing half of the heat to the cylinder wall. This helps to maintain the integrity of the piston itself, protecting it from the appearance of defects;
ensure the tightness of the cylinder so that gas does not enter the engine crankcase;
remove excess oil from the mirror in the cylinder, and prevent its penetration into the combustion chamber.

Signs of worn oil scraper rings

It is advisable for the owner of a car for sale to find out the mileage of the car and the last replacement of the piston rings, if any. The wear of these parts for natural reasons occurs after 150 thousand km. In modern cars, the service life of oil scraper rings reaches 300 thousand km. And in rare cases, operation is possible up to 500 thousand km. If the owner does not properly handle the car, parts wear out much faster. It is also possible for the rings to lie down, which means that they lose their springing property due to heavy deposits between the rings and the piston, as a result of which a tight adhesion to the cylinder wall is impossible.

It is very important to pay attention to the following points indicating significant wear of the rings:

too fast oil consumption (over 0.5 liters per 1000 km in a small car);
the exit of black smoke from the exhaust pipe and the smell of burning indicate the penetration of oil into the chamber;
there is gas ingress into the crankcase if black smoke also comes from the crankcase ventilation pipe;
a decrease in engine power indicates a loss of compression;
dirty spark plugs.

In order for the oil scraper rings to last as long as possible, and in order to avoid their occurrence, you must adhere to the following recommendations:

use high-quality oil, do not mix it, and also make timely replacement;
change the air filter in time, do not allow the operation of the car without an air filter;
use high-quality fuel, change the fuel filter in a timely manner;
warm up the engine before each trip, especially in winter;
avoid severe overheating of the engine, this can lead to the destruction of the piston rings and damage to the cylinders;
do not install new rings on a worn cylinder, they may break and overhaul the engine;
after replacing the piston rings, they need to be given time to run in, so the first 5000 km. do not exceed the number of revolutions of the engine more than 3000 per minute.

Decoking and replacement of oil scraper rings

There are two ways to troubleshoot. If carbon deposits have formed on the piston rings, it can be removed by decoking. To do this, you need to prepare a special mixture of kerosene and acetone, or purchase a decoking agent.

When the oil scraper rings are badly worn, they cannot be repaired, they must be replaced. If you saw such a need, then the price of quality parts will be added to the cost of the car. It is not recommended to purchase cheap rings, as they will only work a couple of thousand kilometers. It is very important that they are made of the same material as the engine.

When purchasing a used car with piston rings in poor condition, all necessary measures should be taken to correct them. Otherwise, there will be a decrease in the power of the car, toxicity will increase, and oil and fuel consumption will increase significantly. Also, worn rings will damage the cylinder bore, resulting in an expensive engine overhaul.