Engine knocking can be devastating to your car when the fuel air charge is ignited by the spark plug, the spark plug releases to early, and an air pocket explodes outside of the normal combustion front. When this happens, the car will make a metallic pinging sound. This causes the cylinder pressure to increase dramatically and will cause damage to parts of your engine. The pollution caused by engine knocking can release poisonous gases called nitrogen oxide and unburned hydrocarbons into the air causing breathing and asthma problems.
This is not a sound or a smell that anyone wants to experience. The engine knocking usually occurs after a person applies pressure to their gas pedal. The sound of an engine knocking can be described as a sound of spray paint being shaken while accelerating the gas.
Replacing the whole engine of a car is not recommended because the knocking may not be actually coming from the engine itself. You will save yourself a lot of time and money by inspecting the engine first to find the culprit for the knocking.
The Most Common Reasons For Engine Knocking
1) An irregular combustion process- Early combustion can happen when the spark plug fires too early after carbons build up inside of the combustion chamber causing a lean air-to-fuel mixture. When the air and fuel mixture ignites before the spark plug has a chance to fire, the two flame fronts collide, and causes a knocking noise.
2) Engine is to hot- If an engine is too hot, this can also cause the engine to knock. In this scenario, the air to fuel mixture will ignite by itself, which will then cause it to spontaneously explode causing a pre-ignition problem.
3) Insufficient gasoline Octane- Having insufficient gasoline Octane levels can cause an improper exhaust gas recirculation. The exhaust gas recirculation system is normally supposed to add a small amount of exhaust gas to the air-to-fuel mixture that limits the combustion chamber temperature.
4) Interior mechanical problems- A rod knock can cause the pistons to change directions if there is an excessive amount of clearance inside the bearings. The rod knock will create a metal hitting metal scenario.
5) Loose timing belt- If the timing belt is loose or faulty in a car, this will also cause the engine to knock when the belt slaps against it.
Ways to Prevent Engine Knocking
1) Correct levels of Octane fuel- Having the right type of Octane fuel can keep an engine from knocking. If the octane is too low, it can cause inadequate compression of the engine.
2) Let car engine warm up- A car engine should be warmed up properly before driving it. Pushing an engine to hard when it is still cold can ruin the pistons.
3) Do not use Turbochargers- Most engines are not designed for turbochargers.
4) Back off of throttle- If a car engine starts to knock, back off of the throttle until you can get it to a mechanic to check it out.
5) Clean engine- An engine can have a build up of carbon deposits that can cause it to start knocking. Having the engine cleaned with a power boost spray can keep the carbons from building up on the engine.
Resources to Help You Understand Engine Knocking
1) Preventing pre-ignition problems
2) Repairing an engine from engine knocking-
3) What does an engine knocking sound like: shown below
- What Causes Engine Knock?
- What is Engine Pinging?
- What is a Four Stroke Engine?
- What is a 4 Stroke Engine?
- What is Engine Misfire?
