3.13.1. Knocks in the engine

If it seemed to you that during the operation of the engine there were sounds which were not earlier, be immediately convinced, whether all as it should be with the engine. Most often knocks in the engine are connected with serious malfunctions for which diagnosing and elimination it is necessary to disassemble the engine in the conditions of service or a garage. However it is possible to try to define independently the reason of knocks to solve, go to car service under the own steam or on the tow.

Prevention
If you have slightest doubts in results of independent diagnostics, get a towing cable. Serious repair of the damaged engine will be more expensive, than services of a tower.

The knock of radical bearings — is very dangerous; immediately stop the motor, it is necessary to go to car service or a garage on the tow. Knock of low tone. It is listened in the lower part of a case, considerably amplifies under loading and at increase in frequency of rotation. Often its emergence is followed by oil pressure drop (the lamp of emergency pressure drop of oil burns almost constantly).
The knock of conrod bearings — is very dangerous; immediately stop the motor, it is necessary to go to car service or a garage on the tow. The sound is rhythmical, ringing, metal, average tone. Considerably increases at increase in loading and completely vanishes at shutdown of a spark plug.
The knock of piston fingers — is dangerous; without loading the engine, it is possible to reach to car service or a garage independently. Rhythmical, high-pitch tone with a sharp metal shade, it is heard on all power setting and amplifies at increase in load of the engine. Completely vanishes at shutdown of a spark plug.
The knock of worn-out pistons and cylinders — is harmless; without loading strongly the engine, it is possible to reach to car service or a garage independently. The sound reminding knock of pottery. It is especially well heard on not heated-up engine, in process of warming up decreases or disappears.
The knock of valves — is harmless; it is possible to reach to car service or a garage independently. Metal knock against the background of the general deaf noise. It is well listened at a small and average frequency of rotation of a bent shaft from a head of the block of cylinders over the locations of valves.
Detonation knocks — are dangerous; however, avoiding strong loading of the engine, it is possible to reach to car service or a garage independently. The ringing metal knocks arising, as a rule, at dispersal of the car. The reason — malfunction of the sensor of a detonation, use of low-octane fuel, an engine overload at too early inclusion of an overgear, a considerable nagaroobrazovaniye in combustion chambers. It is necessary to choose correctly transfer depending on traffic conditions, to refuel gasoline with octane number which is recommended the manufacturer of the car, to check the detonation sensor, to apply special additive to fuel to removal of a deposit on valves and in combustion chambers.