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What Does It Mean When an Engine "Knocks"?

engine knock

There's nothing quite like the sound of a finely-tuned engine. When you hear a strange sound coming from under the hood, you may panic. A knocking sound can be worrisome – here's what it might mean and what you should do to fix it.

Knocking in your engine, also described as pinging, can be related to one of several problems. Some may be easily fixed while others may indicate major damage. The knocking sound often occurs when the fuel and air mixture is incorrect, which causes the fuel to burn in uneven pockets rather than uniform bursts. Left untreated, it can cause damage to the piston and cylinder wall.

Low octane rating

If you put in fuel with an octane rating too low for your vehicle, it can create a knock. To prevent this, use gasoline with an octane rating at or above what the manufacturer recommends. An octane booster, which can be bought at an auto parts store, can help restore the correct octane rating and stop the knocking.

Carbon deposits

Fuels for vehicles are required to have a carbon cleaning detergent, but they may not prevent carbon deposits from forming. This reduces the amount of volume inside the cylinder and increases the amount of compression. Using a fuel additive can usually cure this problem.

Incorrect spark plugs

If any spark plugs other than those recommended by the manufacturer are used, they can cause the knocking sound you hear. The spark plug has a certain heat range, which means it withdraws heat from the combustion chamber. Using the wrong part can prevent it from working correctly.

Deep knocking

If the sound is a deep, loud knock, it indicates that your rod bearings are worn out. Pretty soon, the bearings will fail, which means your car will likely break down and leave you stranded. If you hear such a noise, contact a certified mobile mechanic from YourMechanic for a diagnosis.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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