Engine knocking on cold start
A technically sound engine runs almost silently. However, at some point extraneous sounds become audible, as a rule, it is a knock. The knock can be heard especially clearly when starting the engine on a cold one, when increasing the speed and when shifting gears. By the intensity and strength of the sound, an experienced car owner can easily determine the cause and take the necessary measures. We note right away that extraneous sounds in the engine are evidence of malfunctions, so measures must be taken immediately, otherwise a major overhaul is guaranteed in the near future.
How to determine the cause of the breakdown by knocking in the engine?
The power plant of the car consists of metal parts that interact with each other during operation. This interaction can be described as friction. There shouldn't be any knocks at all. When any settings are violated, natural wear occurs, a lot of combustion products of engine oil and fuel accumulate in the engine, and then various knocks begin to appear.
Sounds can be described as follows:
- muffled and barely audible - there are no serious breakdowns, but diagnostics must be carried out;
- medium volume, clearly distinguishable at the time of cold start and when the vehicle is moving, indicate more serious problems;
- loud knocking, pops, detonation and vibration - the car must be stopped immediately and searched for the cause.
Also pay attention to the duration and frequency of knocking:
- The motor knocks constantly;
- Periodic tapping with different frequency;
- episodic strikes.
There are certain recommendations from the vodi.su portal that help to more or less accurately determine the essence of the problem. But if you do not have too much experience in car maintenance, it is better to entrust the diagnosis to professionals.
The intensity and tone of the knock: looking for a breakdown
Most often, sounds come from the valve mechanism due to a violation of the thermal gaps between the valves and guides, as well as due to the wear of the hydraulic lifters, which we have already talked about on our website vodi.su. If the gas distribution mechanism really needs repair, this will be indicated by a ringing knock with increasing amplitude. To eliminate it, it is necessary to adjust the thermal clearances of the valve mechanism. If this is not done, then after some time you will have to completely change the intake and exhaust valves.
Malfunctions of hydraulic lifters will be indicated by a sound similar to the impact of a light metal ball on the valve cover. Other characteristic types of knocking in the engine when starting on a cold:
- deaf in the lower part - wear of the crankshaft main liners;
- ringing rhythmic beats - wear of connecting rod bearings;
- thumps during cold start, disappearing as the speed increases - wear of pistons, piston rings;
- sharp blows turning into solid shot - wear of the timing camshaft drive gear.
When starting on a cold knock, it can also come from the clutch, which indicates the need to replace the feredo disks or the release bearing. Experienced drivers often use the phrase "knock fingers." Knocking of the fingers occurs because they begin to beat against the connecting rod bushings. Another reason is too early ignition.
Early detonations - they cannot be confused with anything. It is necessary to adjust the ignition, as the engine experiences strong overloads during operation. Detonation can occur due to improperly selected candles, due to the appearance of carbon deposits on the candles and wear of the electrodes, due to a significant decrease in the volume of the combustion chambers due to the deposition of slag on the cylinder walls.
Resounding shocks and vibrations also occur due to the misalignment of the motor. This indicates the need to replace the engine mounts. If the pillow bursts during movement, an immediate stop is required. Rustling, whistling sounds and rattle - you need to check the level of tension of the alternator belt.
What to do if the engine knocks?
If the knock is heard only during a cold start, and disappears as the speed increases, then your car has a high mileage, you may need a major overhaul soon. If the sounds do not disappear, but rather become more distinct, the reason is much more serious. We do not recommend operating the machine with the following types of extraneous sound:
- knocking main and connecting rod bearings;
- connecting rod bushings;
- piston pins;
- camshaft;
- detonation.
If the car's mileage is above 100 thousand kilometers, then the most obvious reason is the wear of the power unit. If you recently purchased a car, you may have filled in low-quality or unsuitable oil and fuel. In this case, it is necessary to perform a complete flushing of the entire system with the replacement of the appropriate filters and diagnostics. Also, a knock appears when the motor is overheated. In this case, you need to stop and let it cool down.
Based on the information received, the driver independently decides what to do next. It may be advisable to call a tow truck and go for diagnostics. Well, so that in the future there will be no tapping, adhere to the elementary rules for operating the vehicle: passing regular technical inspections with an oil change and timely elimination of minor problems.
Loading…
