Elimination of engine noise during cold start, and lubrication of timing rollers 21126 16V on Lada Granta

Possible causes of knocking in the engine

To accurately find the cause, a qualified inspection of the internal combustion engine is necessary using special diagnostic equipment. The main reasons that occur most often:

1. Defects received during the manufacture of a car (on a new car).
2. Poor quality repairs (for example, in a regular garage).
3. The engine crankcase is filled with the wrong brand of engine oil.
4. Using low-quality gasoline or diesel fuel.
5. Violation of vehicle operating rules (motor overload, aggressive driving, etc.).

A knocking sound appears in the engine for no apparent reason; this occurs after a long run, as a result of gradual wear of working units and parts exceeding the maximum permissible values. If unusual sounds occur, the technician must make sure that it is not the gearbox or other transmission mechanism that produces them, but the engine. Based on the nature of the sound, an experienced mechanic determines the location and degree of complexity of the breakdown. This applies to internal combustion engines of any type: carburetor, injection, diesel.

Valves knock “cold” and/or “hot”

As mentioned above, the causes of valve knocking, first of all, include violation of thermal clearances. This gap may be too large or too small. A common situation is when valves knock on a cold engine, but as the engine warms up, the extra sounds disappear. Auto mechanics with extensive experience explain this phenomenon simply.

In a car engine with high mileage, the parts are already worn out, resulting in increased gaps between them. At the same time, the gaps remain within normal limits, that is, such an increase does not affect the proper operation of the systems and the engine itself. The only nuance can be considered an increase in valve noise on a cold engine. After the engine heats up, the metal expands, conditionally “selecting” excess gaps, and the engine begins to operate normally.

Another common situation is that the valve mechanism on a new or recently repaired engine is knocking. In such a situation, you need to check the quality of the adjustments. As already mentioned, the valves may become stuck and require readjustment. Another reason for knocking when cold is wear of the pusher. The formation of dirt and deposits in the pusher area, engine oil leakage and other deviations cause a decrease in the efficiency of lubricant supply. As a result, after starting a cold engine and until a certain warm-up, a ringing metallic sound is clearly heard. In this case, the valves “clatter” a lot.

For a more accurate determination, you can use a simple and accessible method. It is necessary to prepare an empty metal can or mug, which is applied to the surface of the hood and a knock is heard through it. The sound is heard more clearly, which allows you to more accurately determine the malfunction. Let us add that some car enthusiasts confuse the knocking of valves on a cold engine with the knocking of the timing chain. In this case, you need to carefully diagnose the malfunction, that is, check the condition and degree of tension of the chain.

Let's move on to diagnosing and finding out the causes of valve knocking, which cannot be eliminated by standard adjustments.

Primary diagnosis of engine knocking

To make sure that unusual sounds are coming from the motor, you need to:

• install the vehicle above an inspection hole or on an overpass;
• depress the clutch pedal;
• disconnect the engine from the gearbox and transmission;
• check the condition of parts and components that are the most likely culprits for the appearance of extraneous knocking noises (engine mounts, water pump, generator, etc.);
• dismantle parts that cause suspicion;
• If the unusual sounds do not stop, this means that the main problem is in the motor itself.

Types of engine knocks

Experienced auto mechanics can distinguish non-standard extraneous sounds that appear during operation of an internal combustion engine by hearing based on a number of signs:

1. The strength of the blows.
2. Increasing intensity of sounds.
3. Harmonic frequency.
4. Cyclicality.

Depending on the strength of the sounds coming from the operating unit, it is recommended to perform the following actions:

• if the impacts are very strong and cannot be damped by any available means, it is best to turn off the engine and deliver the vehicle using a tow to the nearest service station;
• with medium impacts, which are not audible when you turn on music in the car interior, it is allowed to slowly move independently to the repair shop;
• It is possible to diagnose the cause of the impacts not immediately if the noises coming from the internal combustion engine with the hood open in conditions of complete silence are barely audible.

What actions should be taken when valves knock?

To deal with this problem there is one simple way: you need to take your favorite iron horse to the nearest service station so that a specialist can correct the problem that has arisen. There are times when there is no financial opportunity to do this, or you simply want to repair the car yourself, gaining skills. If you look at it, this case with valves will seem to some like an extraordinary puzzle in terms of repair. Which is a very erroneous opinion. After all, making one wrong move will only increase the sound. For this reason alone, a driver without skills should not try to do this. If you decide to start repairs, be sure to read the repair instructions for your vehicle.

What does impact intensity mean?

If a clear knocking sound in an internal combustion engine appears unexpectedly and does not disappear over time, this means that the working parts are rapidly deteriorating due to the operation of the machine under high load conditions. The result of destruction is exceeding the cyclic fatigue limit of the metal.

If the knocking began with barely noticeable manifestations and, over time, began to gradually intensify to an impossible rumble, this indicates gradual abrasion and wear of metal surfaces.

Important: The intensity of the increase in the sound of impacts depends on the modes in which the vehicle operates: the load on the power unit, the crankshaft speed. When the permissible loads on an internal combustion engine are exceeded, the wear of parts of the cylinder-piston group and the crank mechanism increases. The main sign of defects that have appeared in these groups of elements is an increase in the intensity of extraneous sounds, turning into real noise, with increasing loads.

The intensity of non-standard engine sounds also depends on the quality of lubrication of friction units. List of working pairs in which parts interact closely:

• pistons with piston pins;
• camshaft with cylinder head;
• valve bushings;
• cylinders with pistons, etc.

Characteristics of engine knocks

The sounds coming from an internal combustion engine vary in harmonics. They are voiced and deaf.

A characteristic metallic knock is heard in the engine if:

1. There is contact between parts rotating at high speed.
2. The material of their manufacture is carbide steel.
3. If there is no high-quality lubricant when mating them.

A dull knock in the engine is heard under the following conditions:

1. Interacting parts are made of steels of varying hardness.
2. Small amplitude of movement of associated elements.
3. At the points of their interaction there is a damping (shock softening) layer of lubricant.

Important: A loud knocking sound in the engine coming from the top of the power unit indicates beating of the valves. Sounds that resemble rustling are caused by problems with the timing belt (gas distribution mechanism). Pistons and cylinders make medium or low-pitched knocking noises.

Sharp growling sounds in the crankshaft area

The need for engine overhaul may be indicated by sharp growling sounds coming from the crankshaft area. As a rule, they occur when pressing the gas pedal. In cars with a manual transmission, there are often cases of sharp knocking when pressing the clutch pedal. This indicates depreciation of the clutch basket, crankshaft thrust rings, or failure of the engine thrust mounts.

About the cyclical nature of engine knocks

The frequency of shocks coming from a running internal combustion engine may coincide with the crankshaft speed or be random. If the frequencies coincide, a conclusion arises about defects in parts and assemblies operating in accordance with the cyclicity of the motor. This applies to elements of the following systems and mechanisms:

• gas distribution system;
• crank mechanism.

Accidental impacts are usually caused by the penetration of foreign objects, fragments of worn parts and components into the cavity of the power unit.

"Quading" tapping

Usually, “fading” knocking sounds coming from under the hood are not so critical. They can appear and disappear over tens of thousands of kilometers without any particular reason or change.

Because when the source of noise is the unit itself, this often indicates a malfunction, defects or natural depreciation of moving parts. For example, about problems in the gas distribution mechanism or in the connecting rod and piston groups. Usually these are very sharp knocks, the intensity of which is directly related to the increase in crankshaft speed. That is, the tapping increases in frequency while pressing the accelerator pedal.

Technical causes of knocking in the engine

During the long-term operation of a vehicle, a large number of defects and malfunctions arise, which often cause noise effects and unusual sounds that cause justified anxiety among drivers. Among the numerous signs and causes, the most likely factors include:

1. Engine detonation, accompanied by a characteristic metallic knock.
2. Failure of motor elements due to wear.

Detonation explosions occur due to failures in the distribution of air-fuel mixtures in the cavity of the working cylinders. Instead of uniform combustion, the fuel explodes, causing the cylinder walls to become deformed and the pistons to fail.

The main causes of engine detonation:

• a large accumulation of a thick carbon layer in the lower part of the piston and on the cylinder walls, which leads to an increase in the compression ratio of the fuel mixture;
• failure to regulate the moment of fuel ignition;
• fuel of inappropriate quality is used;
• malfunctions, failure of spark plugs;
• failure to comply with the operating conditions of the vehicle, which leads to additional loads on the internal combustion engine;
• overheating of the elements of the cylinder-piston group;
• malfunctions of components and parts of the exhaust system.

Tip: To minimize the incidence of engine knocking, it is not recommended to use the acceleration mode when overcoming steep inclines.

If knocking in an internal combustion engine is caused by wear, the reasons should be sought in the following:

1. Failure of valve springs.
2. Increased wear of the camshaft cam mechanisms.
3. Faulty bearings - main bearings, connecting rod bearings, which support the crankshaft, increasing clearances.
4. When the pistons wear, the gaps between the rings and cylinder walls increase.
5. Wear of the distribution system parts leads to an increase in the gaps between the cams and the drive, and the timing belt begins to sag.

If no obvious wear of engine components is detected, but knocking is still present, this means that:

• the parts are located with some distortion and work with jamming;
• nodes are deformed;
• the viscosity of the motor lubricant does not correspond to the declared characteristics; a protective oil film does not form on the metal surfaces of the rubbing parts.

Main reasons

There are several reasons why valves in a car may start knocking. Even a novice motorist must know what affects the incorrect operation of these elements and how to prevent knocking from occurring.

The following reasons for the appearance of knocking can be identified:

• Reducing or increasing the clearances (space) between the valve and the pusher. The gap has a certain value provided by the manufacturer. If it changes, a knocking noise may occur;
• Systematic use of low-quality fuel. Extraneous sound occurs as a result of engine detonation;
• If a knocking noise occurs during acceleration or when driving at high speed, there is likely a lack of pressure in the oil system;
• Stretched timing belt;
• Incorrectly installed timing belt;
• Trivial wear and tear of parts.

But this is general information regarding the occurrence of knocking noises. Since we are talking specifically about a hot engine, we need to focus on slightly different reasons.

There are several factors that cause knocking to occur precisely when the engine is warmed up to operating temperature. It can appear when it is cold and persist when warming up, or it can occur directly when the internal combustion engine reaches a certain temperature.

To what extent does engine knock depend on its temperature?

The operating temperature of the internal combustion engine plays an important role in determining the causes of foreign sounds.

A slight knocking sound in the engine when starting from cold often gradually disappears after warming up. This is caused by slight natural wear and tear. According to the laws of physics, the geometric dimensions of components and parts undergo changes when heated, and the existing gaps are safely filled. The engine does not suffer from such knocks when starting, but before starting to move, it needs high-quality warming up.

An unpleasant knocking sound in a hot engine often occurs after it has warmed up. The reason for this phenomenon is frozen motor oil, which did not have time to fill the gaps between worn, deformed components and parts of the power unit. As the internal combustion engine gains speed, the lubricant dilutes. At the same time, the damping qualities of the hot oil are restored: viscosity, fluidity, ability to form a protective film, etc. As a result, knocking in the engine when revving up is noticeably reduced or completely stopped.

Valves knocking on a cold engine

The absence of increased noise and extraneous sounds during the operation of any engine indicates the good condition and normal operation of all components and mechanisms of the power unit. The appearance of a knocking sound in the engine always indicates certain failures, breakdowns or other malfunctions of the internal combustion engine.

One of the most common problems that car enthusiasts often encounter is valve knocking. Next, we will look at why valves knock on a cold engine, talk about valve knocking on a hot engine, and also answer the question of how to determine the cause of such engine knocking.

Engine knocking at idle

If it is noticed that the knocking sound of the internal combustion engine occurs when idling, and when the accelerator pedal is pressed, the sound becomes stronger, it is necessary to urgently diagnose and repair the power unit. Most often this is caused by a failure of valve adjustments. Among motorists there is an expression “valve knocking”. This means that the gap between the camshaft cams and the control arms of the drive mechanism has not been adjusted.

In order to prevent the appearance of characteristic metallic knocks, it is recommended to regularly adjust the valve clearances. Recommended timing is after each run of 10 - 15,000 kilometers.

Valves knocking on Lada Grant during acceleration

There are modifications: 8 valve and 16 valve Lada Grants Sedan / Liftback. One pair of valves provides the intake of the combustible mixture, the other - the release of the exhaust gas flow.

When the motor reaches operating temperature, the metal parts expand. Incorrectly adjusted cold clearances contribute to the formation of knocking, rapid wear of parts, and a decrease in engine efficiency.

To level out the knocking of valves in the design of the Lada Granta Sedan / Liftback, hydraulic compensators (pushers) are used. They try to maintain permissible valve clearances as accurately as possible.

Summary

If the internal combustion engine suddenly knocks while driving, the driver will not always be able to cope with the problem that has arisen. First of all, it is recommended to check the volume of engine oil using a special dipstick. It often happens that after replenishing the missing amount of lubricant, it is possible to get rid of the rumble and knocking in the engine.

If this does not happen, and adding oil does not help, you will have to take the vehicle to a service center. Depending on the nature of the noise, the driver makes a decision on choosing a means of delivering the car: by towing, under its own power, or using the services of a special tow truck.

An attentive and experienced driver always listens to the sounds of his car. If an unfamiliar knock, noise, or clanging appears in the engine, he will immediately try to determine the cause and nature of this phenomenon. If there is something knocking under the hood, this is a signal of one or another malfunction of the car, which can come out - in the literal sense of the word.

Is knocking dangerous?

What can a knock in the transmission or power unit of a car indicate? That somewhere the fastening of a part, assembly or unit has become loose. It is possible that the gap in the mating of moving parts has increased. Or it may be that when the brake pads in the car are extremely worn, a grinding and whistling sound appears when braking. Or that when the battery is discharged or the alternator belt is weak and there is a heavy load in the car’s electrical network, a sharp whistle appears in the alternator bearings. Let's summarize briefly: extraneous sounds, noises, rattles are the result of wear and tear on parts, components and assemblies of cars. Nothing like this can happen to a new, high-quality car.

The main sources of extraneous sounds in the engine

You must understand that not every extraneous sound is a signal of engine malfunction. This primarily concerns knocking noises in the outer parts of the engine. But everyone has a reason that must be found. For example, the flagellum that holds together the bundle of electrical wires has broken. The wires fell apart and when the engine was running, some of them began to muffledly hit some surface. Will this lead to serious consequences? At first, no. If measures are not taken, then after a long time the insulation on the wire will wear out and a short circuit may occur, which, through the combustion of a fuse, will de-energize some part of the on-board network. Parts that have loose fastening bolts often knock. This is also an unpleasant, but not critical situation. It is enough to take the keys and tighten the loose threaded connections yourself.

Types of extraneous noise in the power unit

Here are the most common extraneous sounds in the engine that should alert the car owner:

Air leak into carburetor

Hissing . This specific sound under the hood of the car while the engine is running may indicate air leaks in depressurized vacuum systems or in the cooling system. The consequences can be severe. In the first case, the brake system may fail, in the second, the engine may overheat due to an antifreeze leak. Therefore, you urgently need to go to a car service center to diagnose and eliminate the cause of the hissing sound.

A squealing or sharp whistling sound most likely indicates a weakened drive belt of some component: timing belt, generator, water pump, air conditioning compressor. The belt begins to slip in the drive pulleys and at the same time emit a characteristic squeal. If timely measures are not taken, the belt may break with unpleasant consequences.

Engine Listening Zones

Knocks of different tones inside the engine in the area of ​​the crankshaft, pistons, and valves give rise to diagnosing the operation of the engine as a whole to identify the cause of extraneous sounds. Unusual knocking inside the engine is a cause for the most serious concern. Their appearance may signal the possible high costs of eliminating them. If the liner rattles, you will need to disassemble the engine with grooving or even replacing the crankshaft. A knocking sound appeared in the middle of the block - the connecting rod and piston group was worn out. You will need to completely disassemble the engine, bore the cylinder block, change pistons, rings, pins. If the sound is clearly audible in the upper part, then perhaps the valves need to be adjusted, or perhaps the piston reaches the cylinder head due to a large gap in the connecting rod bearings.

Reasons for the appearance of extraneous sounds in the engine

The reasons and circumstances under which knocking appeared are different. Extraneous noise can be clearly heard both outside the engine and inside it. Internal ones are more dangerous than external ones. The cylinder block contains the crankshaft, pistons, connecting rods, and parts of the gas distribution mechanism. If the knocking comes from this group of mechanisms, then this is always associated with partial or complete disassembly of the engine to eliminate the malfunction. Often the sounds are sharp in nature, which intensifies when the throttle is opened smoothly. If the sounds are loud, with a “light tinkling” of iron and appear with a rapid increase in the speed of rotation of the flywheel, then this indicates detonation - a violation of the fuel ignition regime.

Video: Mercedes 126, found the cause of the knocking in the engine

Knocks from detonation

If the knocking is strong with a ringing “metallic” tint and occurs when the gas pedal is sharply pressed, or under load, then this is the result of detonation - explosive combustion of fuel in the cylinders. Moreover, detonation occurs differently in different types of engines. Gasoline engines have the expression “knocking fingers.” This is not entirely correct. In fact, during abnormal fuel combustion, the piston skirt knocks when it passes top dead center. Gasoline detonation is the result of refueling with poor fuel with a low octane rating, incorrect valve timing adjustment, and prolonged engine operation in an overheated state. To eliminate detonation, it is enough to cool the engine, adjust the fuel injection and ignition systems, and fill the tank with gasoline in accordance with the technical regulations of the car.

Diesels also have fuel detonation, but their reason for its formation is different. This is an early injection of diesel fuel or a lean fuel mixture, which arises from improper operation of the pressure valve in the high-pressure fuel pump (HPF). Moreover, the sound will be loud, ringing, similar to the blows of a piston on the surface of the cylinder head. In such cases, they say that the diesel engine operates “hard”. This impression arises because the compression ratio of diesel engines is much higher than that of gasoline engines, so in normal operating condition the distance between the piston and the block head is microscopic. You can get rid of detonation by restoring the operation of the pressure valve on a special stand in a service station.

Even in diesel engines, at idle speed, the knocking of the plungers is clearly audible. This is a design feature of almost all engines of this type. These sounds do not pose any threat. Diesel engines have been used with them for more than one year. In engines with gasoline injection, an experienced ear hears the “clicks” of fuel injectors, which are also inherent in most engines of this type. They do not pose any serious threat to the engine, and in no way affect its performance characteristics.

Valve mechanism knocks

If the valve bushings and hydraulic compensators are worn out, the gaps between the ends of the valves and pushers have increased - ringing, clear sounds will be clearly audible in the area of ​​the cylinder head. It's not difficult to get rid of this. It is necessary to change worn parts and dirty engine oil. Rinse and clean all channels and valve mechanism parts from dirty deposits and adjust the thermal clearances in the valves. This work is specific, requiring special equipment, cleaning agents, and tools. Therefore, it is performed at technical inspection stations. First of all, this applies to cars of domestic and foreign production that are under warranty.

Lada Granta (2019). Extraneous knocks and noises in the engine

Why does the engine knock at idle?

The engine, like any other mechanism, wears out over time, which leads to breakdowns. The sound of a knock in the engine makes it clear that something is wrong with the “heart” of the car. If you are not eager to figure out what’s going on, or are simply afraid to finally finish off your “iron horse,” contact the service station. If you are firmly confident that you can find out the cause of this or that knock yourself, be patient and read the article to the end. A sign that it is the engine that is knocking is the sound that comes from the hood. Also, there is a slight drop in oil pressure. This can be determined by the control light, which will light up even when the engine is warm and idling. Important! On a cold engine, the light should not light up, even if the engine knocks loudly. It happens that the engine does not knock, but the oil pressure has dropped. You need to press the gas pedal and listen to the sound. If you hear something similar to a hammer hitting cast iron, then you are at the initial stage of knocking. If the engine knocks at idle, and when you press the gas pedal the sound only intensifies, then you should immediately start repairing your engine.

Valve knock

Valve knocking is the sound most often encountered by motorists. Almost any used car has valve knocking. Of course, this sound is not always critical. However, if a loud knocking noise appears when the engine is running at any speed, it is worth doing repairs.

Causes of valve sound: wear of the camshaft housings; valve rocker wear (it will click loudly); The holes in the camshaft through which oil is supplied to the rocker are clogged.

The main cause of knocking is the gap between the levers and the camshaft cams. If the gap between the parts increases, the cam will knock on the rocker. The result is a metallic knock. Don’t think that this sound is not a fact that you have a breakdown. The larger the gap, the greater the damage will be, which will ultimately put the engine out of working condition. Therefore, you should not wait for the moment when your engine simply breaks down and you will have to shell out a large sum for its repair. The ideal option is to adjust the valves every 10-15 thousand km. Also, knocking in valves can be caused by detonation of the power unit. Signs of detonation: black smoke from the exhaust, increased vibration, overheating of the power unit and decreased power. A metallic clatter may also occur as a result of detonation. And yet, guesses are good, but you need to find out exactly what the breakdown is, especially if you yourself will be replacing parts.

Reasons for valve knocking in cars:

Check the engine exhaust valve. Check the oil and its pressure. If the pusher wears out, you will hear a knocking sound in the engine even when it’s cold. Poor oil supply to the valves due to dirt and dust in the pusher. The same applies to leaks (in this case, during overheating, a characteristic sound can be heard). If everything is in order with the pressure, then it is worth checking the valve clearances (they may need to be adjusted). Now let's move on to another scenario: the valves knock during acceleration. This may be due to a lack of oil. When you add oil to the required level, the knocking should stop. If it doesn’t help, and the knocking noise increases with increasing load, then most likely your crankshaft bearings are damaged. Continuing further movement with such a defect is very dangerous, since the engine will soon fail. Important! Knocking in the power unit can also occur due to low-quality fuel!

Camshaft knock

Let's move on to possible camshaft problems that you will have to face one way or another if you own a car. How to distinguish camshaft knock from valve knock? The knock of the camshaft is more “dull” and it appears during a “cold” start of the engine. If the sound becomes louder as you gain speed, this is definitely a problem in the camshaft. Important! The knock of the camshaft will only be heard during a “cold” start of the engine, since during idle time the lubricant leaves the parts that rub. If the camshaft begins to knock, this can lead to considerable waste, since the knocking can be caused by a faulty hydraulic compensator. Following this, if there is a knock in the camshaft, then it is worth sending the car for diagnostics. Since if you delay with this procedure, then in the future you will have to shell out money not only for replacing the hydraulic compensator and bearings, but also for repairing the shaft itself. If your car is not equipped with a hydraulic compensator, then you can drive about 50 thousand km with a knock in the camshaft. Only then you will have to completely change the engine (or carry out major repairs). The following are the causes of knocking noises in the camshaft. Wear of the camshaft bed. (self-repair is impossible!) Malfunction of the lubrication system (in this case, even a small deviation can lead to knocking) Change in the shape of the camshaft or its damage (burst supports, broken journals). Fuel supply is interrupted. The cams are worn out (in the event that the engine knocks “on hot”). Interesting fact! The first attempts to make front-wheel drive were carried out using conventional universal joints. However, if the wheel moved in a vertical plane and, at the same time, was rotary, the outer hinge of the axle shaft had to work in extremely difficult conditions - with angles of 30-35°. And if the angles were more than 10-12°, then the power loss in the cardan transmission sharply increased, moreover, the rotation was transmitted unevenly, the wear of the joint increased, the tires wore out at a faster rate, and the gears and transmission shafts began to work with greater overloads. Therefore, a special hinge was required - a constant velocity joint - devoid of such disadvantages, transmitting rotation evenly, without depending on the angle between the connected shafts.

Piston group knock

Before moving on to analyzing possible problems with the piston group, I would like to look at another reason for metallic knocking in the engine. And this reason is the gearbox. You can hear engine knocking at idle if you have problems with the gearbox.

You can determine whether the gearbox is knocking or something else in the following way: with the engine running, depress the clutch pedal. If the knocking stops, the problem is in the box. This problem can occur in front-wheel drive cars when there is a lack of oil. If the oil is normal, the problem is in the bearings (they are worn out). A knock at the bottom of the engine can also be associated with the piston group. This is the case when, due to the missing millimeter of the groove, your cylinders will knock like “hail on slate”. Now let's move on to the reasons for the knocking of the piston group: Piston misalignment due to too large a gap: the cylinder diameter is too large or wear. Impact of the piston in the direction of the pin (lateral impact of the piston on the cylinder wall). Impact of the piston pin on the piston pin stoppers. Possible damage due to impacts in the swing direction: Installation gap too large. Failure to comply with the direction of assembly of a piston with a displaced axis. Heavy duty pin support. Such a number of different reasons for knocking in a piston is due to the fact that the piston is not an ideal cylinder, which means that everything in it is not in an ideal shape. The first problem with knocking is the gap between the “skirt” and the cylinder wall. To avoid knocking, you need to measure the size of the “skirt” down to millimeters. Important! If you do not have the necessary tools or have no experience with such a breakdown, we strongly recommend that you contact the service. The next reason for knocking in the piston is an incorrectly installed cylinder. It will manifest itself as a strong knock at all speeds. Another reason is that the piston head reaches the block gasket. In this case, the copper edging will be jammed. If this is a problem, you need to make sure the gasket is the correct size. We calculate the size of the gasket as follows: the maximum height of the protruding piston above the block + half a millimeter (this is how much the piston should have in reserve) + 0.3 mm for shrinkage of the gasket. Flatten it down to get the thickness of the new gasket.

Crankshaft knock

Wear of the crankshaft bearings and the appearance of a gap in them is the main reason why the crankshaft knocking appears in the engine. It appears on both gasoline and diesel engines. But this doesn't always happen just like that. Wear can also accelerate due to low-quality engine oil, foreign particles in it, engine overheating and insufficient oil level. This knocking noise occurs when the engine starts. After all, the oil is still cold and has not reached the crankshaft bearings, which is why, most often, you hear a dull knock in the engine. This is the first alarm bell. Afterwards the knocking noise subsides, but it can also be heard at idle speed. At low speeds the sound is dull, but as the speed increases, it becomes louder. Its frequency is equal to the frequency of the internal combustion engine, as in the case of detonation. It is almost impossible to determine that the sound comes from the knee shaft on your own. Possible knocking noises in the engine are a sign of urgent repairs to your car.

Knock of crankshaft journals

Signs of this breakdown appear in low pressure in the lubrication system and a dull knock appears, which occurs at any speed. If you change the oil, you can finally verify this breakdown. If you used to fill in semi-synthetic oil, then try to fill in with mineral oil and soon you will notice that the sound has become quieter. If you fill the oil the other way around, the knocking will noticeably intensify. But the best thing is to go to a service center and have the engine repaired before it completely breaks down. A dull knock of the crankshaft is heard from the bottom of the engine; in the cabin it will appear on the left side when the car is warmed up. Why is this happening? A dull knock of the crankshaft occurs due to gaps in the main or connecting rod bearings, which were formed as a result of wear of the shaft journals or bearings. A gap of 0.07 mm already indicates the need for urgent repairs.

There are several reasons for the increase in clearance: Mechanical impurities have entered the bearing with oil. Oil filters cope well with their load, but if the filter has not been changed for a long time, it becomes clogged. Insufficient lubricant supplied to the bearing. When such breakdowns occur, a light comes on, indicating insufficient pressure in the bearings. This occurs due to a clogged oil filter or a faulty oil pump. Scratches on the shaft journals after repair or improper storage. Unacceptable ovality of the shaft journals. Having measured all the shaft journals for ovality, you should focus on 0.005 mm and below. If you take up to 0.010, then the bearings will last you 5000-15000 kilometers. Engine operation without oil. Presence of water in oil.

A knock in the engine can cause a huge number of malfunctions (from minor to critical). Following this, you should not shelve such a problem as engine knocking at idle, if it is not related to the weather and temperature “overboard”. The best solution, if an incomprehensible knocking noise occurs, is to contact a service center.

There is a knocking sound in the engine, causes and repair options

Knock in the engine - causes of malfunction and repair methods Knock in the engine, causes and repair options When starting the car, some drivers are faced with the fact that they hear an incomprehensible noise and feel vibrations in the engine. This is a fairly common problem if your car is more than 10 years old, or its mileage has already exceeded one hundred thousand kilometers.

If you have not carried out routine diagnostics on your “iron horse” for the last couple of years, then there is a high probability of hearing a knocking sound in the engine of a new car that is only a couple of years old. What causes this unpleasant and potentially damaging engine noise?

There may be a little confusion among car owners regarding which engine mechanisms can produce noise in the engine. Often, in the appearance of any ticking noise, drivers tend to see disturbances in the operation of the engine pushers (cylinder cams). However, a car engine consists of hundreds of parts, and its operation depends on the smooth operation of all systems.

The most common causes of noise or knocking in the engine: There is a knocking in the engine, causes and repair options

1. Increasing valve clearance. 2. Crack in the valve spring. 3. Wear of the camshaft cams. 4. Malfunction of connecting rods (crankshaft connecting rod bearings). 5. Malfunction of the piston system. 6. Lack of optimal oil pressure. 7. Thermal detonation. 8. Increasing the gaps between the liners and valves. 9. And 118 more reasons for engine noise.

If the pusher malfunctions, a characteristic ticking sound appears, which can be distinguished among other noise. It is the ticking sound that gives auto mechanics the basis to diagnose a broken pusher, but the same characteristic engine noise appears during the following breakdowns:

1. Crack in the rocker arm. 2. Worn camshaft valves. 3. Poor quality lubrication or lack of pressure in the pump.

Operating principle of the pusher

There is a knocking sound in the engine, causes and repair options

The pusher is located at the end of the lever (rocker arm), its second end interacts with the crankshaft blades when the engine starts. When the cam profiles are rotated, the pusher initiates the movement of the valve to open and close it. The second common name for a pushrod is a lifter because its job is to raise the rocker to the desired length.

The pusher is connected to the rocker arm with a locking screw. By adjusting the screw, you can increase or decrease the level of valve lift in the engine cylinder.

Primary noise in the motor occurs when the cups wear out - the pushers are located in a special head (cup) which wears out and deforms over time. Noise during a cold start of the engine, which subsequently disappears, may occur due to a mismatch in the temperatures experienced by the parts of the assembly. The pusher cups are made of steel, and the head is made of aluminum.

Effect of motor oil

There is a knocking sound in the engine, causes and repair options

With use, when the engine oil becomes contaminated and its viscosity increases, the friction between the pushers and the camshaft increases. This leads to both nodes starting to wear out. The critical moment of wear of parts is characterized by the appearance of noise during valve operation.

If there is a lack of lubricant, the same effect is possible. If there is insufficient lubrication, in addition to the pushers, the cylinder valves, heads, and pistons begin to wear out quickly.

In addition to the fact that insufficient lubrication of engine elements leads to irritating engine noise, the car’s power indicators are significantly reduced, speed drops and acceleration time increases.

A worn pusher or camshaft will lead to the fact that sooner or later the valves will not open at the desired point, the supply of the fuel mixture will be limited, and the car will fall into the emergency zone.

If the oil has not been changed for more than 50,000 km, and its control has been ignored, then damage will affect all engine elements, with the camshaft being the most expensive part of the repair.

When diagnosing a car for engine noise, checking the quality of the oil should come first. The following parameters should be checked:

1. Proper oil level. 2. Optimal viscosity.

If the car used oil of high or low viscosity, which is not suitable for the technical parameters of a particular car, and the mileage on such lubricant exceeded 10,000 km, then all engine parts should be checked, since deformation of many components has clearly occurred. The appearance of noise in such cases is a characteristic sign of metal-to-metal friction.

If the driver ignores the technical requirements for changing the oil for a long enough time, then oil scale clogs all the filters, and when changing the fluid, do not forget about replacing all the filters, otherwise very soon the engine will knock again.

Correct pushrod adjustment

There is a knocking noise in the engine, causes and repair possibilities. Incorrect installation of this unit is another reason for the appearance of ticking noise in the engine. If, after adjusting the valves, the glasses begin to knock, this may indicate excessive tightening of the fasteners. When the corresponding screw is released, the knocking stops.

Often noise appears after significant wear of the pusher wells - in this case, you need to completely change the head; such noises cannot be eliminated by simply replacing or adding oil.

Valve adjustments should be made when the engine is cold, as the valve stem thermally expands after the engine warms up, and for optimal pushrod performance, sufficient clearance should be left without tightening the adjusting screw. On the other hand, when adjusting, you should not leave a large gap for the pusher so that the valve remains in the open position for the exact stroke time.

If valves overheat for a long time, cracks can form in them, and fine chips can form in the engine cylinders.

When adjusting the tappet, use a feeler gauge to check the proper distance between the rocker arm bracket and the valve stem. If the data sheet contains parameters for factory adjustments, you should rely on them when setting the gap in the pusher adjusting screw.

Knocking (noise) in the engine. Cold or hot, as well as at idle. Main reasons

Fuel injectors

On many cars, it is not the power unit itself (or some parts in it) that knocks, but the attachments. In particular, these can be fuel injectors that are installed on the ramp. During operation, they inject fuel into the intake manifold, and this process is accompanied by a click.

Injectors

This sound can be confused with the chirping of, say, valves, but essentially there is nothing wrong with it. As I wrote above, this is just such a job.

Pushers and hydraulic valve compensators There are both normal operation and breakdowns. Old engines were usually equipped with valve pushers; now hydraulic compensators are being installed more and more (what they are and what is better - I wrote here). So here it is:

The old system takes into account the thermal gap (when cold) between the pusher and the camshaft cam. Therefore, after starting the engine, you can hear a characteristic knock, but it goes away after the metal heats up and this gap is removed. This is a completely normal operating mode designed by the engineers. True, due to long runs, the contact surfaces may wear out - a larger gap appears. And the noise may already appear when the engine is warm, then only adjusting the valves will help.

Pusher

A more modern system (based on hydraulic compensators) ideally does not knock at all! This is because here the thermal gap is adjusted automatically and it is always minimal. However, if the noise begins to appear specifically from the valves, it means that the hydraulic compensators are either: - out of order, - dirty. You need to take it apart and look. SEPARATELY, I would like to highlight the engine oil, if you fill this system with oil of the wrong viscosity, knocking will also appear.

Hydraulic compensator

In any case, if it is constantly noisy both cold and hot, then you need to either adjust it or disassemble and clean (change if necessary) the expansion joints.

Valve train chain

It is the chain and timing belt that usually does not knock. Due to high mileage, the chain mechanism can wear out and stretch (and now they come in different plate or roller types). Ideally, it should be tensioned by a special device - a “tensioner”. But if the mileage is large, then it extends to the full (limit) and can no longer press it. There are also special shoes (they also wear out), and play may appear in the sprocket itself.

Double row roller chain

You need to understand that the chain mechanism is quite complex and after a certain mileage (150 - 250,000 km) everything will need to be changed completely. Chain - “tensioner” - dampers - possibly the sprockets themselves (often there are phase shifters).

On turbocharged engines, the replacement interval can be much shorter, for example, on the 1.4 TSI (EA111 generation), the chain ran no more than 60 - 70,000 km.

Replacement is not cheap, all because you will need to disassemble the engine, and there are a lot of spare parts. BUT if you don’t do this, the chain mechanism can jump a tooth or two and make a mess. To the point that it can bend the valves. And this is completely different money.

Phase shifters

They can be installed on machines with chain and belt mechanisms. Inside the phase shifter there are two moving parts, one is attached to the camshaft, the other engages with a belt or chain. When oil is supplied, they can move against each other (I won’t go into detail now, but I already have an article about this).

Phase shifters on both shafts

There are special partitions between the chambers that control the oil pressure in the chambers. Over time, both these partitions and the walls of the phase shifter can wear out. And a knocking sound similar to a cracking sound may appear. It comes from the top of the engine

Pistons - cylinder walls

Next comes heavy artillery. There is no longer a simple knock, and they are all caused by complex breakdowns. Or rather, wear and tear.

Pistons - usually the piston skirt wears out (the lower part, if exaggerated, it calms it down) and it begins to move a little from side to side, creating a knocking sound. Moreover, oil consumption increases and engine power decreases

Piston skirt

The piston pin is the part that connects the connecting rod and the piston itself. If there is a gap in it (about 0.1 mm), then knocking noises appear

Piston pin

Cylinder block walls. Due to excessive wear, overheating, insufficient lubrication, or a damaged catalyst, they too can wear out. Scores may appear on the walls, play may form at the piston - and, of course, noise. There is no escape from this. Badasses

A major overhaul of the engine can fix all this; simple methods are not enough.

Crankshaft - liners Here, the knock mainly comes from the so-called liners - connecting rod or main liners, and it is also associated with engine wear. If the radicals - the sound is metallic, slightly muffled - is clearly audible in the lower part (crankcase) of the engine. It can be heard well at low speeds of a warmed-up power unit. Caused by a drop in oil pressure and the appearance of a gap (0.1-0.2 mm) between the crankshaft journal and the liner itself.

Main bearings

Knocks are also possible when an engine oil of the wrong composition and viscosity is used.

Connecting rod bearings - here the situation is similar, only wear appears at the “neck” and connecting rod bearing. Here the sound may be more distinct, it may increase with increasing speed.

Connecting rod bearings

Both knocks are dangerous, because the engine can jam (well, let’s say, a piece of the block can be torn out). And the liner can rotate due to excessive wear and clearance. It is advisable to eliminate such knocking quickly.

These are probably the most basic causes of knocking (various noise), I now don’t take our VAZs where the adsorber valve knocks, and all this is quite easily diagnosed and removed.

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