Our car maintenance tips and tricks
Nov 01


When driving, have you noticed any rattling or, maybe more accurately, hollow banging noises? If so, “engine knocking” is the term for this. You do not want to hear the sound of an engine knocking. It is the metallic sound the engine makes when the gas pedal is depressed. It is also known as spark knocking, detonation, or pinging.

Engine banging happens when an air/fuel combination ignites in a different pocket after the air/fuel mixture in the combustion chamber has already been lit by the spark. Unburned hydrocarbons (HCs) and nitrogen oxide (NOx) are released into the atmosphere when an engine knocks or pings. These are hazardous gases that have a yellow-brown appearance and may be seen in a polluted sky. They negatively impact respiratory conditions including emphysema and asthma.


Putting too little octane-rated fuel in your car- Did you know that the anti-knock index, is another name for the octane rating of gasoline? Manufacturers suggest certain octane ratings for their cars to retain peak performance. Pinging can happen when there is insufficient exhaust gas recirculation or when you employ an excessively lean air-to-fuel combination (EGR). By introducing a little quantity of exhaust gas to the air-to-fuel combination entering the combustion process, the EGR system eliminates engine knocking. 

The maximum combustion chamber temperature is therefore constrained. You may buy an octane booster to raise fuel that has a low octane rating to levels that allow for appropriate operation if you have been using such fuel. Try using a new brand of gasoline if you discover that you are having issues even with the recommended octane level. Consult your owner’s handbook to find out what octane grade is best for your particular car.

Early combustion- A “spark knock” is a common term for premature combustion. Lean air/fuel mixtures, carbon build-up in the combustion chamber, and premature spark plug firing all contribute to early combustion.

If the cylinder is firing properly, the spark plug will ignite the fuel/air combination, and a flame front will begin on one side of the piston and burn across the top to the other side, creating a rapidly and uniformly expanding gas that presses down on the top of the piston. The two flame fronts will clash and produce the knocking noise if the air/fuel combination ignites before the spark plug burns.

Warm engine- The engine might ping if it gets too hot. Another early combustion scenario would be this. It happens when the air to fuel combination spontaneously “lights off.” The air-to-fuel combination will burst on its own if the cooling mechanism is unable to manage the temperature in the combustion chamber. The term “pre-ignition” has been used to describe this.

Engine knocking can also result from the following issues:

  • Cylinder walls covered in carbon deposits
  • Wrong spark plugs for the car
  • Worn water pump bearing
  • Timing belt tensioner failure or slack (knocks when the timing belt slaps against it)
  • Main crankshaft bearings that are broken
  • A flywheel or flex plate that connects the engine to the transmission that is chipped or damaged
  • Air conditioning compressors may knock when they ice up or fail
  • When the pistons fire an alternator with worn rotor bearings can knock

Finding the reason of engine banging can be challenging; thus, it must be carefully and thoroughly evaluated. If your engine is knocking, do not hesitate to contact Smart Mechanics with any queries, suggestions, or issues you may have. Your car will keep being safe and durable if you swiftly fix problems like engine banging and carry out normal maintenance. Do not trust just anybody to service or repair your car; trust the professionals at Smart Mechanics in Bishop Stortford.

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