Engine knock Polo sedan: causes, possible solutions

Volkswagen Polo engine knock

During the operation of the Volkswagen Polo car, the car owner may encounter such an unpleasant phenomenon as engine knock. The reasons for the origin of the sound can be different, but in any case, it is not recommended to ignore the extraneous noise.

The appearance of a knock in the power plant indicates that in the area of mating parts there has been an increase in the gap above the critical.


Knocking caused by engine mounts

During operation the supports of the power unit are subjected to wear and tear. Also their mechanical destruction is possible. Knock from the engine side in this case will be heard during intensive acceleration or braking.


To diagnose problems with engine mounts you should visually inspect each pillar. Presence of mechanical damage, deformation or other signs of wear suggests the necessity of their replacement.

Engine knocking due to oil problems

As a result of low oil level there may be a knock in the power unit. To diagnose the malfunction, remove the oil dipstick and use it to determine the level of engine lubrication. If the oil volume is close to the minimum value or below the “MIN” mark, it is necessary to add oil to the “MAX” level.

Also engine knocking can be caused by poor oil quality or oil change intervals. To eliminate the knocking sounds, change the lubricant to the products recommended by VAG. At the same time it is required to fully comply with the change intervals.

Oil that does not match the viscosity level recommended by the manufacturer can also cause engine noise. To eliminate the noise of the power plant you must buy the oil that fully meets the SAE standards 5W-40, 5W-30, 0W-30.


Octane mismatch leads to detonations in the powertrain. This in turn causes engine knocking. Most often strange noises occur during intensive acceleration or at idling revolutions.

Table – Impact of octane number on the engine knocking

Octane rating Description
АИ-92 Knocking occurs frequently during acceleration
АI-95 Knocking occurs mostly at low rpm or during intensive acceleration
АI-98 The engine is running more quietly. The knocks are not noticeable.

To eliminate the knocking it is necessary to fill the car with gasoline of octane number 95 or 98. If the car is equipped with HFO, then for diagnostics of the knock reasons it is possible to compare the work of the power unit on different types of fuel.

What to do if the engine speed swings when warming up?

Knocking of power unit because of hydrocompensators

The design of the engine of the Volkswagen Polo sedan is such that the knock of the hydro-compensator is heard on the unheated motor. At the same time, car owners note that in the cold engine can knock from a few seconds to five minutes. On reaching the temperature of more than 60 degrees, the extraneous sounds disappear.

To diagnose a malfunction, you need to open the hood and listen to the operation of the power unit immediately after the startup. You will hear a ringing sound at the top of the engine. An increase in rpm will cause the tone to change.

Many car owners note that the knocking of hydro-compensators is not a critical failure. Operation of the car is possible for a long time without damage to the main elements of the engine. However, if the car owner has decided to eliminate the extraneous sound, it is necessary to identify the knocking hydraulic tappet. For this purpose, it is necessary to change the hydro-compensators one by one, listening to the sound of the running motor.

Very often the sound, knocking hydraulic tappets, goes away when the engine oil is changed. Therefore, before looking for a failed hydrocompensator it is necessary to change the engine lubricant in the engine.

Knocking in the piston group

The design of the Volkswagen Polo sedan powertrain is such that most car owners clash with piston knock. This is due to miscalculations in the creation of the engineers of the engine. In most cases, the knocking is not dangerous to the powertrain. In spite of this, if you hear a humming sound from the middle of the cylinder block, it is necessary to contact a service station or a good mechanic.

One of the main causes of knocking pistons is excessive wear of piston rings. In this case the extraneous sounds are more evident when the engine is cold. After the engine warms up, the knocking decreases or disappears completely. Further operation of the power plant is dangerous because of possible scuffing on the cylinder mirror. This in turn will lead to a costly overhaul. In case of excessive wear of piston rings, it is necessary to disassemble the engine and replace them.

Also knocking in the piston group is possible due to excessive wear of the piston pins. This malfunction can be diagnosed by characteristic signs:

  • the engine knocks most intensively during acceleration;
  • the engine generates characteristic sounds when braking the power unit;
  • unscrewing the spark plug from the cylinders results in complete disappearance of the engine knocking.
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To eliminate the malfunction it is necessary to disassemble the cylinder-piston group and make defect inspection of the piston pins. Excessively worn elements should be replaced.


A muffled metallic sound may indicate wear of the main bearings. The appearance of gaps between the crankshaft and the liner indicates that further operation of the engine without repair may lead to scuffing and the need for overhaul.

Why the engine of Polo sedan knocks

Perfect mechanisms exist, perhaps, only in the futuristic worlds described by science fiction writers. In their imagination, the assemblies of machines never wear out and are not affected by corrosion and various substances. There is only the basic essence conveyed by the main parts of the device.

In reality, however, it’s not all that simple. Every part of the car requires timely maintenance. Manufacturers establish certain limits of passing of maintenance, replacement of consumables and diagnostics of serviceability of the main units of the car. The man has not yet invented perpetuum mobile: it is necessary to compensate the defects by constant service of the car.

Perpetual engine

It is not for nothing that we spoke about the eternal engine. Though it is not in the car, it performs the same functions as its human analogue. The “heart” not only drives the car, but also emphasizes the individual character of its owner, lives the same life with it and “grows old” at the same time.

Volkswagen Polo in the sedan body is a unique car created by the popular German automobile concern. With its high ground clearance and fashionable electronic “features” adapted for the Russian winter, it conveys the harsh temperament of our climatic and road conditions.

Separate attention should be paid to the engines installed in the new Polo sedans from 2015. Both units run on gasoline and their dynamics are ideal for driving on our roads.

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    The 1.6-liter CFNA with 4 cylinders and 16 valves develops 105 horsepower and accelerates to a “hundred” in 10.5 seconds.

VW engine

If used properly, the “engines” from Wolfsburg can serve a careful driver for a long time. But the precise German technology can also fail. High overloading of the engine affects the efficiency of its components.

Widespread problems and ways to solve them

Many owners of the Polo sedan face extraneous noises arising in the engine. To hear an unexpected knock in the driving organ of the car – it is very unpleasant. He clearly does not bode well. In such a situation, the main thing is to remain calm and try to independently determine the source of the noise. The saddest outcome, which can happen in this case – rotation of the crankshaft liner. For any car this is the end: call a tow truck and take your “favorite” to the service.

How to predict a knock on the Polo sedan? Why do difficulties arise?

The most important criterion is the level of oil pressure in the engine. If the indicator is below the 2 millibar mark, you may soon enjoy the glorious “tap” beat off the engine liner.

Oil level icon

The quality and type of the filled engine oil affects the wear. If low-grade “synthetic” or mineral grease is filled in the engine, then there is no doubt – the aggregate will not endure and will start banging. Therefore, it is important to use only high-quality oils and try not to save on them.

The work of the engine of the Polo sedan can be influenced by the type of fuel. The oil viscosity and performance of the spark plugs depends on it.

To increase the life of the engine liner, experts use special “cushions” that soften the friction of the parts. They do not cost that much, and you can find them at any auto store. If a “cushion” is already installed in the engine, you should check the condition of the auxiliary element before disassembling the “engine”. It is possible that it is it, and not the liner, that knocks.

Engine cushion

What to do, if annoying knocking starts to bother you? To diagnose the problem you can go to a car service and pay a considerable sum of money for the service. Another option, which “beginners” are afraid of, is to check everything independently.

Armrest for VW Polo Sedan

There is nothing to be frightened of. You just need to know what units you should examine.

The weakest place in the Polo sedan is the valves. These elements are more often exposed to physical influence. In general, the problem of valves in the engine is typical for both domestic cars, as well as for top foreign cars.

Disassembled engine

You can determine the functionality of the valves by their sound. An extraneous knock appears at idle or medium engine speeds. It is a tinkling metallic clang, which is strongly noticeable against the background of the power plant operation. Tappets have a similar sound. But their tone is slightly higher. In addition, it can change during the operation of the engine.

The knocking of tappets is a standard phenomenon for most foreign cars and is not as dangerous as the noise in the valves. To get rid of the annoying sound completely, you will have to spend a lot of time and money.

Second place on the pedestal of problems are the pistons of the Polo sedan. The difficulty is related to the wear of the rings, which need to be changed urgently. There is nothing super complicated in diagnosing the pistons. The sound is humming, as if the vessels of clay are beating. Most often the complication is detected when starting the power plant in cold weather. It’s minus temperatures outside and the engine is still icy. The problem recedes after a few minutes of warming up the “engine”. The knocks either stop or reduce their tonality, becoming less noticeable.


When the pistons are knocking, you should drive carefully so as not to overload the engine. You should not delay with the replacement of components – a small hitch can result in an expensive repair.

If there is a high rhythm with a characteristic metallic clang, it means that the piston pins are knocking. Loudness of a sound increases with revolutions and increase of engine load. You can get rid of the unpleasant “chord” by removing the high-voltage wire from the ignition system. With such a problem it is necessary to immediately seek qualified help.

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Similar signs have crank bearings. A rhythmic “rattle” and a medium tone are the main symptoms of malfunction. The rattle also disappears when the high voltage cable is removed from the ignition.

A decrease in the volume of the sound occurring at the bottom of the crankcase indicates a failure in the main bearings. Again, as the RPM increases and the load on the “engine” builds up, the tone begins to rise. Simultaneously with the appearance of the “whine”, as a rule, oil pressure decreases. In this case, the best way out is to stop the car completely and call a car tow truck (or faithful friends who will help tow the sedan to the garage).

Use of low-quality fuel with low octane number can cause detonation knocking. They are not difficult to distinguish – they have a strong metallic sound. You can not hear the knocking at medium revs. They become noticeable when speeding up. To get rid of this “trouble”, it is enough to fill the tank with more reliable benign gasoline, tune the ignition system and reduce the load on high gears. Otherwise it will be necessary to clean combustion compartments and engine valves.

Finally, a couple of words should be said about hydro-compensators. They also have a tendency to knock. The sound can be caused by air ingress in the cavities, located above the plunger, contamination of gaps of the devices or their trivial wear. A gradual decrease in sound volume indicates that dirt is getting into the assembly. If the engine continues to knock evenly, it means that air got into the system. Usually in the service centers they change the whole piston system with both hydro-compensators to eliminate the problem for sure.

Hydraulic compensators

A good assistant for independent diagnostics of the sound of Polo sedan engine is an ordinary phonendoscope, used in medicine.

In a cold cold knock may appear at any moment. It usually occurs at 15-30 thousand kilometers. There are rare samples of Polo sedan, on which the problem with pistons or other elements of the power plant occurs at the very beginning of the mileage.

A few tips to combat engine knocking

The main methods of combating the knock in the engine, which are offered by masters of maintenance and experienced motorists:

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