The appearance of foreign sounds in the power unit is always a warning signal for the owner of the vehicle, but it is the metal grinding in the engine that most often portends serious mechanical destruction. Unlike the thud or whistle of the belts, this sound indicates direct contact of metal parts that are normally separated by an oil film or process gaps. Ignoring such symptoms in the early stages can lead to a jamming of the engine and the need for its complete replacement, so the reaction should be instant and competent.
Diagnosing the sound source requires careful analysis of the nature of the noise, its frequency and dependence on the rotation of the crankshaft. Often drivers confuse the grinding of the engine itself with the noise of the attachments or transmission, which leads to incorrect diagnosis and unnecessary financial costs. Understanding the physics of the process of friction of metal against metal will help you quickly localize the problem and make the right decision about further operation of the car.
The main reasons for the occurrence of grinding on cold and hot
The nature of metallic grinding can be very different depending on the temperature of the power unit. On a cold engine, the sound is often due to thickening of the engine oil or thermal expansion of parts that have not yet reached the operating parameters. oil-pump may not cope with the pumping of thick liquid, creating short-term oil starvation in the upper points of the lubrication system.
But if the grinding doesn't go away after warming up, the situation becomes critical. Hot oil has less viscosity, and if the gaps between rubbing vapors are increased due to wear, the protective film breaks. root-liners Or the rod necks already have production, and the metal begins to rub against the metal with every second of work.
Also, seasonal factors and the condition of technical fluids should be considered. In winter, grinding can occur due to the freezing of condensate in the exhaust system or pump, but this is more of an exception. lubrication does not perform its function, and the parts of the GRM or crank-shaking mechanism work in extreme conditions.
⚠️ Warning: If you hear a sharp metal grinding as you start the engine, immediately turn off the engine. Continuing to even the nearest service can make simple repairs a necessity for a bulkhead.
It is important to distinguish between the nature of the sound: intermittent grinding often indicates problems with the gas distribution mechanism, while continuous hum with a metallic hue is characteristic of slip bearings. Experienced mechanics recommend not relying only on hearing, but using a stethoscope or long screwdriver to precisely localize the source of vibration.
Diagnostics of problems of gas distribution mechanism
One of the most common causes of metal noise is the chain or belt of the timing, and the associated elements. The tensioners of the chains often fail, no longer holding the necessary pressure, causing the chain to rattle against the wall of the casing. Visually, this is difficult to determine, but the sound usually has a clear rhythm, depending on the frequency of rotation of the crankshaft.
If you're using a belt drive, it's not the belt that makes the grinding, but the tension rollers or the pump, and when you break them, they start to make a sound that resembles rolling metal balls or dry grinding. gear-piece They are shattered, as their wear leads to disruption of the gas distribution phases.
How to check the tension of the chain indiscriminately?
To do this, you can remove the valve cover and carefully, without turning the shaft, try to move the chain away from the star, and if the suction exceeds 10 mm or the chain sags freely, its life is exhausted.
And the phase rotators, if they're designed by the engine, are also something that happens when the internal locking mechanisms fail, and often they get a start-up crack that drivers mistake for the grinding of the whole engine. VVT-i coupling Similar systems require precision and the use of special tools.
- 🔍 Check the tension of the chain manually (when the lid is removed) - the backlash should not exceed the norm.
- 🔍 Examine the stars for "licking" teeth or chips.
- 🔍 Listen to the zone of the cylinder head – there is most often localized noise of the GRM.
Replacing the HRM components in a timely manner is the best way to avoid costly repairs, and ignoring the slightest rustle in the system can lead to a collision of the valves with the pistons, which is guaranteed to bring the engine down.
Critical malfunctions of the crank-shaking mechanism
The worst dream of any motorist is a grin from the bottom of the engine, where the crankshaft is located. liner Or critical wear on the necks of the crankshaft, and the oil is either completely absent or has lost its properties, and the shaft begins to literally chew on its support surface.
The knock of rods is often described as the impact of a metal hammer on an anvil, but when it is worn hard, it turns into a continuous grinding, which is because the rod neck loses its geometry and the slip bearing stops working, and the oil pressure drops to zero, as evidenced by the tanning of the corresponding indicator on the dashboard.
| Type of malfunction | Nature of sound | Dependence on turnover | Oil pressure |
|---|---|---|---|
| Pivot of the liner | A deaf knock turning into a grinding | Increases with increasing turnover | Critically low. |
| Reciprocating wear | Metal ringing, tinkling. | Heard on singles, subsides under load | Normal. |
| Piston breakup | Chaotic, strong grinding and clanging | Constant, very loud. | Falling sharply |
| Bullies in cylinders | Dry crackling, grinding | Depends on the cylinder load. | Maybe I'm fine. |
If the diagnosis shows problems with CSM, the car is impossible to operate, even short-term operation of the engine with the twisted liner leads to heating and deformation of the crankshaft, making it unfit for grinding, in such cases, a complete defect is required and, most likely, a replacement of the unit or engine assembly.
☑️ Actions in the grinding of the CSM
Foreign objects and attachments
The metal sound source is not always inside the cylinder block. It's often the grinding elements of attachments that come into contact with the rotating parts when they break down. The generator, the GUR pump, the air conditioner compressor, all of these units have bearings that break down with the characteristic metallic screech.
The exhaust system is particularly important, because a burnt-out inside of a catalyst or a broken valve can move freely inside the silencer, creating sound that passes through the body like a grinding engine. heat-shieldwhich from vibration can fall and touch the exhaust manifold.
Sometimes a foreign object can enter the engine through the air intake, a nut, a bolt, or even a piece of rag that enters the intake manifold can cause trouble. Once in the cylinders, a solid causes a knock and scratches the walls of the cylinders, which requires immediate intervention.
- 🛠 Remove the belt of the hinged units and start the engine for a few seconds - if the sound is lost, the problem is in the hinged one.
- 🛠 Examine the space around the engine for fallen nuts or tools.
- 🛠 Check the mounting of the engine airbags, as the displacement of the unit can cause contact with the body elements.
⚠️ Note: When removing the belt of the attachments do not operate the engine for a long time, as the pump of the cooling system will cease to work, which will lead to overheating in 3-5 minutes.
A technical stethoscope is often used to accurately diagnose attachments, and if you apply it to the generator or pump, you can clearly hear where the bearing is breaking, and this allows you to replace only the defective assembly, not the entire set of belts and rollers at random.
Effects of oil quality and lubrication system
The quality of the engine oil and the state of the lubrication system are critical in preventing metal grinding. Using oil with inadequate viscosity or waste life leads to the fact that it can not create the necessary separating film between the parts. hydrocompensators and phase-turners.
A clogged oil filter or a mesh of an oil receiver creates an oil starvation, the pump starts pumping air or an emulsion, and the oil simply does not reach the top of the engine, and as a result, camshafts and rockers start to work "dry", emitting a piercing grind within seconds after launch.
Always change the oil filter every time you change the oil, even if you pour expensive synthetics. The old filter can be filled with wear products, which will block the oil from accessing the engine.
And you also need to look at the state of the oil pump, and the wear of its gears or the reduction valve causes the pressure to drop in the system, and the motor can work normally on idlers, but when you get up, the pressure drops, and you start to wear the friction pairs intensely.
Regular monitoring of oil levels and condition is a mandatory procedure for each owner, and the presence of metal shavings on the probe or in the oil being drained is a direct indication that the engine has already begun irreversible processes of destruction.
Remediation and prevention of breakdowns
Eliminating metallic grinding is directly dependent on the diagnosis made. If the problem is in attachments, replacing the bearing or the entire assembly will solve the problem quickly and relatively inexpensively. In case of problems with HRM, you will need to open the upper part of the engine and replace the chain, asterisks and tensioners.
The most difficult and expensive scenario is to repair the CSM, which involves removing the engine, disassembling it completely, defecting it, grinding the crankshaft or replacing the cylinder block, and often it is more cost-effective to replace the engine with a contract engine than to repair a badly damaged unit.
Prevention of such problems is to observe intervals of oil change, use quality consumables and be attentive to any changes in the operation of the engine. Do not wait until the grinding becomes unbearable - contact specialists at the first sign of malfunction.
Replacing the oil and filters in a timely manner prevents 80% of the problems associated with metal grinding in the engine.
Can I get to the service if the engine is grinding?
Absolutely not. Any metal grinding means that there is an active destruction of parts. Every minute of operation of such an engine brings the moment when repairs will become economically impractical.
Will replacing the oil with a more viscous one help?
Temporary noise reduction is possible if the gaps are slightly increased, but this is not a solution, but a delay. A viscous oil is thicker, but it will not restore the worn metal or remove the output on the parts.
Why does the squeak appear only in the cold?
The cold gaps between parts are maximum due to the lack of thermal expansion, and the oil is still thick. If there is wear, then in the first seconds before the oil arrives or until the parts are "drummed up", noise is possible. However, constant grinding at the cold is a sign of a serious malfunction of the tensioners or liners.