Když motor začne klepat: Komplexní průvodce

When an engine starts knocking, it is a clear sign of a serious problem that can lead to engine failure if not addressed promptly. Knocking or pinging sounds from the engine are caused by the premature ignition of the air-fuel mixture in the combustion chamber, occurring before the piston reaches the top dead center. This can be attributed to various factors, including incorrect fuel octane level, improper ignition timing, carbon buildup on the intake valves, and engine overheating.

Příčiny klepání motoru

Incorrect Fuel Octane Level

One of the primary causes of engine knocking is the use of low-octane fuel in high-performance engines. High-performance engines are designed to operate with fuel that has a higher octane rating to prevent premature ignition of the air-fuel mixture. Using low-octane fuel in these engines can cause the air-fuel mixture to ignite prematurely, leading to a knocking or pinging sound.

The octane rating of a fuel is a measure of its resistance to premature ignition, also known as “knocking” or “pinging.” The higher the octane rating, the more resistant the fuel is to premature ignition. For example, regular gasoline typically has an octane rating of 87, while premium gasoline has an octane rating of 91 or higher.

When using low-octane fuel in a high-performance engine, the air-fuel mixture can ignite before the piston reaches the top dead center, causing the characteristic knocking or pinging sound. This premature ignition can lead to increased stress on the engine components, potentially causing damage over time.

Nesprávné časování zapalování

Another factor that can contribute to engine knocking is improper ignition timing. If the ignition timing is advanced too much, it can cause the air-fuel mixture to ignite too early, leading to knocking or pinging sounds. Conversely, if the ignition timing is retarded too much, it can cause the air-fuel mixture to ignite too late, leading to incomplete combustion and reduced engine performance.

The ignition timing is the point at which the spark plug fires, igniting the air-fuel mixture in the combustion chamber. Proper ignition timing is crucial for efficient engine operation and to prevent knocking or pinging.

Incorrect ignition timing can be caused by various factors, such as a malfunctioning ignition system, worn spark plugs, or a problem with the engine’s computer or sensors. Regular tune-ups and maintenance can help ensure that the ignition timing is properly adjusted and maintained.

Carbon Buildup on Intake Valves

Carbon buildup on the intake valves can also contribute to engine knocking. Over time, carbon deposits can accumulate on the intake valves, causing them to stick and preventing them from closing properly. This can lead to an improper fuel-air mixture and incomplete combustion, resulting in knocking or pinging sounds.

The presence of carbon deposits on the intake valves can disrupt the air-fuel mixture, leading to uneven combustion and the potential for premature ignition. This can be particularly problematic in direct-injection engines, where the fuel is injected directly into the combustion chamber, as the carbon deposits can interfere with the fuel spray pattern and the air-fuel mixture.

Regular engine cleaning, including intake valve cleaning or carbon deposit removal, can help mitigate the issue of carbon buildup and prevent engine knocking.

Přehřívání motoru

Engine overheating can also cause engine knocking. When an engine overheats, the air-fuel mixture can ignite prematurely, leading to a knocking or pinging sound. Overheating can be caused by several factors, including a malfunctioning cooling system, low coolant levels, or a faulty thermostat.

Overheating can increase the temperature and pressure inside the combustion chamber, making the air-fuel mixture more prone to premature ignition. This can result in the characteristic knocking or pinging sound, as well as increased stress on the engine components.

Maintaining a properly functioning cooling system, ensuring adequate coolant levels, and regularly replacing the thermostat can help prevent engine overheating and the associated knocking issues.

Prevence klepání motoru

when engine starts knocking

To prevent engine knocking, it is essential to address the underlying causes. Here are some key steps to take:

  1. Use the Correct Fuel Octane Level: Ensure that you are using the recommended fuel octane level for your engine, as specified by the manufacturer. Using a higher octane fuel can help prevent premature ignition and engine knocking.

  2. Udržujte správné časování zapalování: Regularly have your engine’s ignition timing checked and adjusted by a qualified mechanic to ensure it is within the manufacturer’s specifications.

  3. Udržujte motor čistý: Regularly clean the engine, including the intake valves, to prevent carbon buildup that can contribute to engine knocking.

  4. Ensure Proper Cooling System Function: Regularly maintain the cooling system, including checking coolant levels, flushing the system, and replacing the thermostat as needed to prevent engine overheating.

  5. Provádějte pravidelnou údržbu: Follow the manufacturer’s recommended maintenance schedule, including tune-ups, to keep your engine in optimal condition and prevent issues that can lead to knocking.

By addressing the underlying causes of engine knocking and following a regular maintenance routine, you can help prevent this serious issue and prolong the life of your engine.


  1. A Guide to Job Analysis – ERIC: https://files.eric.ed.gov/fulltext/ED273802.pdf
  2. Is there good coverage of how Intel became so uncompetitive? – Hacker News: https://news.ycombinator.com/item?id=25009017
  3. Olej v sání vzduchu u motorů s přímým vstřikováním? – Fóra MBWorld.org: https://mbworld.org/forums/c-class-w204/588708-oil-air-intake-direct-injection-engines.html