Causes of engine knock in a car
Content
If the car engine knocked, not everyone immediately understands what it means. It is important to understand the causes of such a malfunction, to assess the conditions in which it arose, the consequences to which it can lead if nothing is done. Therefore, the car owner must know what to do in the event of such a nuisance.
What is engine knocking
The often appeared bulge indicates that the gaps between the parts have increased significantly in the area of conjugation of specific elements. If the lubrication and cooling systems work without problems, noises and knocks appear at gaps that, on average, double or even exceed the allowable specifications. The impact force directly depends on the increase in the gap.
This means that the knock in the engine is the impact of the parts against each other, and the load at the point of contact increases greatly. In this case, the wear of spare parts will accelerate significantly.
Attention!
The wear rate will be affected by gap size, material of components and parts, loads, lubrication efficiency and many other factors. Therefore, some nodes can painlessly travel tens of thousands of kilometers in the presence of an impact, while others fail after a few kilometers.
In some cases, the power unit knocks even with normal clearances and if the parts are not badly worn.
Why the engine can knock: reasons
During the operation of the vehicle, the knock in the engine may increase unevenly, quickly or slowly. Causes of malfunction:
- detonation and heavy loads on the engine;
- distortion of the internal part of the motor;
- jamming of individual elements;
- loss of engine oil properties.
If the hard material timing elements are worn out, the engine can run for the same length of time without change. If soft parts wear out while working together with components made of harder material, extraneous noise will begin to increase noticeably.
Idle
If the engine knocks at idle, this sound is not dangerous, but its nature has yet to be determined. At rest, noise occurs due to:
- touching the generator or pump pulley;
- vibration of the timing box or engine protection;
- the presence of a gear;
- loose crankshaft pulley.
The situation is aggravated when a crack appears in the flywheel of a car with an automatic transmission. It is possible that the fastening of the camshaft sprockets is loosened, and at idle the noise appears due to the loosened crankshaft gear on the key.
Hot
The appearance of knocking when using an internal combustion engine is possible due to a critical reduction in the working spaces between the elements inside the engine. When cold, the oil is thick and the metal in the products does not expand. But as the engine temperature rises, the oil becomes liquid, and a knock appears due to the gap between the worn elements.
The engine overheats due to:
- Oil deficiency. In this case, the pairs rubbing against each other will work without lubrication, which causes their premature wear and knocking.
- Crankshaft and its shirts. The latter are made of a softer metal than the crankshaft, so they wear out due to a violation of the lubrication of surfaces or service life. However, they can turn around and call.
- Valve. The main reason is the wear of the valve rockers. Camshaft oil valve may be clogged.
- Hydraulic compensators. Knocking is often the result of a low oil level or insufficient oil pressure. Wear cannot be ruled out.
- Phase shifters. In an internal combustion engine with a belt or chain drive, the mileage of which exceeds 150-200 thousand km, internal parts wear out. Sometimes coking of oil channels is observed.
- Pistons and cylinder walls. The geometry of the pistons is broken as the power unit wears out. Damage to the piston rings and piston pin is also possible.
- Bearing and crankshaft. Wear and tear occurs naturally, but incorrect installation during repair is also possible.
- Detonations. Symptoms: deaf explosions in the cylinders of the internal combustion engine, arising from the sudden ignition of the fuel.
All these causes of irregularities can be eliminated.
To the cold
A situation may arise when a cold engine, after starting, began to work with a slight knock, which disappeared after warming up.
Attention!
There can be many reasons for this, but it's not scary. It is possible to drive with such a malfunction, but the internal combustion engine must always be preheated.
Why does the internal combustion engine make noise when cold, and after warming up, the noise disappears, a common question for car owners? This is due to the natural wear of parts. After heating, they expand and their gaps normalize.
Without oil
Another reason for knocking when starting an internal combustion engine is a failure in the lubrication system. Due to the poor performance of the oil pump, the lack of oil and the clogging of the channels with impurities, the oil does not have time to reach all friction surfaces in a timely manner, and therefore a strange sound is heard.
Due to difficulties with the lubrication system, oil does not enter the hydraulic lifters, and without it, their operation is accompanied by noise.
Adding oil will help correct the situation. If this does not help, it will need to be replaced with a preliminary flushing of the system.
After oil change
If, in the presence of a strange sound, the internal combustion engine starts to work harder and smoke, the reason may lie in the oil:
- his absence;
- low quality;
- pollution;
- antifreeze enters;
- wear or damage to the oil pump;
- high viscosity.
A high viscosity lubricant inhibits flow, especially in cold weather, resulting in loud noises and knocks in the overhead valve train. Oil filters can always do their job, but they need to be changed from time to time. If the filter becomes clogged, the valve opens, opening the oil passage for situations where the filter cannot pass oil.
What to do if the engine knocked on the go
If the power unit began to knock, you need to find the cause and eliminate it. You can do it yourself or turn to specialists.
Attention!
In some cases, the driver decides that the problem lies in the engine and takes his car to a service. But it may turn out that this is not the reason.
If you find a strange sound on the road, you should not move on, as there is a high probability of a sad outcome. It is better to drive to the nearest gas station and contact the specialists. But if the noise does not increase and is heard in the hydraulic compensator, razdatka or injection pump, you can continue on your way.
The engine can detonate for various reasons, which are easy to eliminate, the main thing is to identify them correctly. If you can’t do it yourself, you should turn to professionals.
