One of the most unpleasant situations in which every driver risks finding himself is an unexpected knocking sound in the car engine.
Reliably determining the causes of its occurrence is not an easy task. The only thought that immediately comes to mind is that the engine is faulty and requires immediate diagnosis and expensive repairs.
In general, if the engine knocks, it is the result of metal parts hitting each other. It is accompanied by a sharp increase in load at the points of contact of interacting parts. As a result, parts are destroyed, and the faster the stronger the impact.
Engine knocking may occur due to:
- manufacturing defects (on a new car);
- unprofessional repairs;
- using motor oil whose characteristics do not comply with the recommendations of the vehicle manufacturer;
- refueling with low-quality fuel;
- improper operation (vehicle overload, aggressive driving style, etc.)
The engine knocks for no reason only in the case of natural wear of parts to the limit values.
In order to quickly assess the situation and make the right decision, you must first make sure that it is the engine that is knocking, and then try to classify the knock.
Typical causes of ringing “fingers” during normal operation of the internal combustion engine
If the “fingers” knock during acceleration in the Kalina, the mass air flow sensor may have failed. If it is not working correctly, then the ECU will receive incorrect information and issue incorrect commands. Another reason is an incorrectly set ignition timing. For this reason, the point at which the fuel will burn maximum is approaching TDC. This leads to increased pressure in the combustion chamber. If the “fingers” knock when accelerating on a Ford Focus, then the knock damping sensor may have failed. It's definitely worth checking this item. If it stops working, it should be replaced.
Poor quality fuel is the cause of all the troubles that happen to cars. This has already been described in detail above. It should be noted that knocking fingers is not always a problem that has formed during the use of the car. There are situations when a car comes from the factory with incorrectly connected sensors. This ultimately leads to detonations and knocking. This problem is especially dangerous because the engine is being run-in and detonation is especially harmful for it. It should be excluded.
Exact localization of the problem
Some knocks can be characterized unambiguously, since they are not similar to each other. For example, pistons that have already exhausted their service life sound dull and can be compared to light blows on clay products. Sometimes there are clicks. The gap of 0.3 mm is compensated by the expansion of the metal, so this problem does not appear on a warm engine. The sounds are more distinct when the car has cooled down to street temperature or the driver suddenly takes his foot off the gas pedal.
Problems with piston pins are also easy to identify. The engine produces a distinct metallic sound, which is better heard when accelerating or releasing the gas. Often the problem arises due to low-quality fuel, which ignites early, which creates a characteristic sound. And if this sound is distinct, then the crankshaft liners are more difficult to hear.
If the “knee” liners have exhausted their service life, the car owner will hear a slightly muffled sound that will come from the engine crankcase. But this situation does not appear without a reason, since the element is simple and reliable in operation. And the first thing we pay attention to is what “consumables” were purchased for the last service station. The problem may arise as a result of using low-quality oil, so first you need to change it and flush it, and not do a major overhaul of the engine.
The problem with the connecting rod bearings can definitely be localized. The sound increases gradually as the car accelerates. With such a problem, it is useless to change the oil or fuel, since all you can do is turn on the emergency lights and wait for the tow truck. If you decide to travel independently, the internal combustion engine will jam, which will lead to large material losses.
Driver actions when knocking occurs
We will have to repeat this truism for the umpteenth time, but if a knocking noise occurs while driving the car, it is recommended to check the current oil level. To do this, you will have to stop and use the probe to perform this simple procedure.
If the knocking appeared on a cold engine, but then disappeared, there is nothing to worry about. You can calmly, without overloading the engine, drive to a garage or car service center, carry out diagnostics and find the cause.
When a knocking noise appears when the engine is hot and gradually increases, in such a situation it is better to stop the vehicle, turn off the engine and call a tow truck. Trying to get to the service center on your own is potentially dangerous, since with every kilometer the cost of repairs will increase in proportion to the destruction of engine components.
Regardless of the causes and provoking factors, any knocking in the engine becomes a reason to carry out diagnostics and carry out some repair work. Depending on how correctly you can determine the causes of knocking, you will be able to minimize the financial and time costs of repairs. Some faults require surface dismantling and simple manipulations. Others involve complete disassembly of the engine, which requires a lot of time, effort and certain skills. It is not always worth taking on such work yourself.
What to do if the engine knocks while driving
If the power unit starts knocking, you need to find the cause and eliminate it. You can do this yourself or contact specialists.
Attention!
In some cases, the driver decides that the problem lies in the engine, so he sends his car for overhaul. But it may turn out that this is not the reason.
When an extraneous sound is detected on the road, you should not continue driving, since there is a high probability of a sad outcome. It is better to go to the nearest service station and contact specialists. But if the noise does not increase and can be heard in the hydraulic compensator, timing belt or injection pump, you can continue on your way.
The engine can knock for various reasons, which are not difficult to eliminate, the main thing is to correctly identify them. If you can’t do this yourself, you should turn to professionals.
How is detonation formed?
If the engine runs stably and without interruptions, the combustion process of the air-fuel mixture maintains its consistency. The motor operates quietly, there is no extraneous noise. The process begins with a spark from the spark plug, after which the entire combustion chamber is filled. This happens equidistantly.
In the case of detonation or detonation combustion, the process looks different. The entire amount of the mixture of fuel and air injected into the chamber ignites simultaneously. This leads to a sharp and strong increase in the temperature of the cylinders and the pressure inside them. During detonation, the mixture does not burn completely. In areas where the largest volume of unburned fuel remains, active chemical compounds gradually appear.
