What is Engine Knocking?

engine knocking

Engine knocking is a term generally used to describe an abnormal sound produced by a vehicle engine when there’s a problem with the controlling of fuel/air mixture within the engine cylinders. Generally, this irregular sound is heard when the automobile is idling & it can be either strong or weak. A strong knock normally indicates an issue that should be resolved to avoid irreversible damage to the vehicle engine.

Reasons for Engine Knocking

Engine knocking is caused by a small explosion which takes place outside of your engines normal timed rotation. There are several abnormalities which can cause the timing to be off, causing the engine to ping or knock. Below are some of the potential causes for an engine knocking:


  • Improperly mixed fuel
  • Irregular cylinder pressure
  • Timing off
  • Low coolant level
  • Sharp edges on valves or pistons
  • Overheating
  • Overheating exhaust valve
  • Inappropriate spark plugs
  • Cooling system problems
  • Slipping fan clutch
  • Improper Gasoline Octane

How to Fix Engine Knocking

Below are three less expensive methods to fix engine knocking.
Octane Rating – The octane rating of gasoline is often referred to as the AKI (anti-knock index). If you use gas, which has an AKI that is too low, you can utilize an octane enhancer to bring it back to levels which will enable normal function. If you utilize the correct rating & your engine still has problems, consider using a different brand of gasoline. Using gasoline with a higher anti-knock index than the manufacturer suggests shouldn’t have any negative effect.

Use a Detergent – Your vehicle cylinder walls can easily collect carbon deposits. When deposits form, compression can increase and cause knocking. While most fuels consist of a small amount of detergent to avoid these buildups, putting additional detergent to keep the engine cylinders clean cannot hurt. Consult with your mechanic to see what detergent is most effective for your vehicle engine.

Check Spark Plugs – If your car does not have the appropriate spark plugs installed, knocking can take place. Make an effort to change your spark plugs if changing your fuel does not work. Check out your owner’s manual to find out what your manufacturer suggests.
These three methods are effective and less expensive to fix engine knock. If your vehicle is still experiencing a knock, try & take it to a reliable Idaho falls auto repair shop.

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