Do you hear an unnatural sound coming from your hood? It might spark knock or pinging. If you don’t know what spark knock is and why it happens, read the article.
What is a Spark knock? You might have heard the noise coming from your car auto parts. It’s a sound that comes from valve train clatter in a high-mileage engine when it gets exhausted. The sound is also known as pinging, detonation, pre-ignition, etc. If you ask me to describe the sound, it would be a loud clank as if a hammer slammed a metal. The noise can be heard from under the hood when the engine is taking a load, for example- towing, carrying heavy luggage, etc. Let’s discuss why this sound happens and what you can do to stop it from happening.
Before we continue to explore the noise we need to understand a few basic concepts. That includes understanding the detonation and pre-ignition.
Pre-ignition
When the air mixtures burn before the spark plug fires pre-ignition happens. This happens due to an overheated spark plug, advanced ignition timing, a lean fuel mixture, due to a glowing chunk of carbon that’s is off, etc.
Detonation
Detonation happens when the air mixture in a cylinder explodes instead of burning inside the combustion chamber. The flame moves and expands through the cylinder. This happens because of the formation of heat inside the combustion chamber. You may expect damages to the pistons, crowns, and rings if the case goes out of hands.
One reason for such detonation can be excessive compression. This is caused by the accumulation of carbon on the piston crown and valves. The carbon takes up space in the combustion chamber, increasing the compression ratio.
If you put a comparison with vintage to modern-day engines we’d see that the high compression engines consumed gas with lead. The anti-knock additives used to prevent spark knock. Engines these days which are turbocharged can also be prone to knock as a result of forced induction of air getting higher which also affects the compression ratio.
There are some factors as well. For example, the engine getting hotter than usual due to heavy load, a messed up ignition timing, a problem with EGR valve, etc. A defective knock can be another option for the sound.
Vacuum leakage at the sensors can cause spark knock as well. If you need to diagnose the leak, spray carburetor cleaner around the presumed leakage area. If you hear a slight change in idle then there is indeed a leak.
A jammed catalytic converter can raise combustion chamber temperature which can lead to spark knock.
Conclusion
Any type of unnatural sound coming from your vehicle is concerning. If you hear this pinging, clanking sound, you need to take your car or vehicle to the repairing shop. If its spark knock you’ll already observe the “check engine light” light flashing. If your mechanic identifies the problem you can buy auto parts either in shops or online. You can find them based on car parts names or lists.
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