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Engine Knock Diagnosis & Repair


You depend on your vehicle for just about everything when it comes to your daily life. Whether it’s getting you to work, your kids to school or any other errands that you may have to take care of, you need your car to stay reliable and dependable to keep your routine in motion.
One of the quickest ways to derail that routine is if you begin to hear an unusual noise while driving and when that sound is coming from the engine, it’s tough to imagine an inexpensive way to fix it. It’s important however, to listen closely as various sounds can indicate different issues in different locations under the hood. One sound to listen for that needs to be repaired as soon as possible is engine knock. The most common occurrence for this is when the engine is having an improper combustion process, either from carbon buildup in the combustion chamber or the spark plug firing too soon.

Common causes of engine knock

However, in addition to those, there are multiple reasons for engine knocking to occur and various ways to make sure it’s properly diagnosed. If you notice any unusual sounds coming from the engine, either knocking, a ping or even full on metal on metal grinding, be sure to have your vehicle checked by a professional to avoid further damages to your engine and car. Here are just a few of the most common causes of engine knock.

  • Lower Quality Fuel– If you drive a vehicle that requires a higher octane of fuel, it’s important to make sure you use only the fuel recommended for your vehicle. Using a lower grade fuel or a lower quality one, can lead to increases in the combustion chamber’s temperature along with even higher cylinder pressures which then leads to the knocking. The higher a fuel is rated, the better the fuel resists combustion so in higher pressure engines, the higher quality fuel is needed to properly function.
  • Using the Wrong Spark Plugs– This is a more common issue then you’d expect, oftentimes drivers misunderstand what the manufacturers recommend or use cheaper ones that they know are incorrect to try and save some money. Using the wrong plugs can lead to combustion chamber deposit buildup and incorrect running temperatures, which are two of the most usual causes of engine knock.
  • Engine Temperature is Too High– If your vehicle’s cooling system isn’t keeping the combustion chamber’s temperature regulated, then the air-to-fuel mixture in the chamber to spontaneously begin to explode. This occurrence is also often referred to as “pre-ignition” and can lead to engine ping or knock.

Ways to repair engine knock

So now that you know some of the most common causes for engine knock, it’s important to also know the various ways to repair it to make sure that your vehicle gets the proper work done. There are a few ways to repair it at home but if these don’t improve the sound, a trip to your trusted mechanic is the best bet.

Check Engine Light ON

  • Use Higher Level Gas– Somewhere in the manual or near the gas cap, there should be the recommended fuel octane level for your vehicle. Switching to a higher level fuel is usually only recommended if you’re attempting to repair engine knock as most cars in the United States are equipped to handle 87 octane fuel while higher-end sports and performance cars may require higher.
  • Octane Boost Additives/Detergents– If you think the knock may be caused by old or bad gasoline, there are a few different remedies you can try before visiting the mechanic. Fuel injector cleaner is meant to help clean dirty combustion chambers and the injectors themselves, while an octane boost additive will help the fuel perform better and help prevent improper combustions through at least a few fill-ups.
  • Check the Spark Plugs– As mentioned before, an improper spark plug can lead to a variety of combustion issues and added strain to your engine so if you have the tools needed to change them yourself, make sure that they’re the proper fit for your vehicle and if not, replace them with the correct ones to potentially repair the engine knock.

Ask professional help, if you’re uncomfortable

These are just a few ways to try and remedy the situation at home, but if you’re uncomfortable with any of those options or would like to seek a professional opinion, schedule an appointment with an auto mechanic immediately to get an accurate diagnosis the first time to make sure your engine is repaired properly right away.