There was a knock in the engine

If it seemed to you that during the operation of the engine there were sounds that were not there before, immediately check whether everything is in order with the engine. Most often, a knock in the engine is associated with serious malfunctions, for diagnosing and eliminating which you will have to disassemble the engine in a service or garage. However, you can try to independently determine the cause of the knock in order to decide whether to go to a car service on your own or in tow.

WARNING: If you have the slightest doubt about self-diagnosis, remove the towline. Serious repairs to a damaged engine will cost more than the services of a towing vehicle.

Knock of main bearings (audible at the very bottom of the cylinder block) - very dangerous; stop the engine immediately, you will have to go to a car service or garage in tow. A low-pitched knock that increases noticeably under load and with an increase in the crankshaft speed. Often its appearance is accompanied by a drop in oil pressure (The oil pressure warning light is almost permanently on).

Knocking rod bearings (audible in the middle of the cylinder block) - very dangerous; stop the engine immediately, a car service or garage will have to be towed. The sound is rhythmic, ringing, metallic, medium tone. Significantly increases with increasing load and completely disappears when the spark plug is turned off.

Knock of piston pins (bugged at the top of the cylinder block) - dangerous; without loading the engine, you can drive to a car service or garage on your own. Rhythmic, high tone with a sharp metallic tinge, audible in all engine operating modes, intensifies with increasing engine load. Completely disappears when the spark plug is turned off.


The sound of worn pistons and cylinders (audible in the same part of the engine as the sound of the piston pins) - is not dangerous; without heavily loading the engine, you can drive to a car service or garage on your own. A sound reminiscent of the clatter of pottery. It is especially well heard on a cold engine, as it warms up it decreases or disappears.

Valve knock (audible in the upper part of the engine in the area of \u200b\u200bthe head cover) - is not dangerous; you can drive to a car service or garage on your own. A metallic thump against the background of a general muffled noise. It is well audible at low and medium speeds of the crankshaft from the side of the cylinder head above the valve locations.

detonation knocks are dangerous, but are usually eliminated by replacing the knock sensor or refueling with quality fuel. Avoiding a strong engine load, you can drive to a car service or garage on your own. Voiced metallic knocks that occur, as a rule, during acceleration of the car. The reason is the failure of the knock sensor, the use of low-octane fuel, engine overload with too early upshift, significant carbon formation in the combustion chambers. It is necessary to apply a special fuel additive to remove carbon deposits on valves and combustion chambers.