Q: Car makes knocking sound

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My car runs but makes a horrible knocking sound like the piston wants to come through the block. I was told that I blew a valve or had a valve-related issue. And when it runs too long, it overheats but maintains oil levels.

A valve train issue usually sounds more like a tapping sound similar to a pencil tapping quickly on a desk. Depending on the engine, a vehicle with a 4 cylinder engine can have as many as 16 valves. If several of those have problems, it sounds like a bunch of pencils hitting the desk. When it is something in the "bottom end" of an engine, meaning piston, crankshaft, rod or mains, the knock is like a carpenter hitting the side of the engine with a hammer. This sounds more like what you are describing. A lower engine knock is very serious. It requires at the minimum opening up the engine to replace bearings if no other damage has been done. Depending on mileage, it might be best to rebuild the engine altogether. Seek help from a qualified mechanic that can go and inspect the vehicle’s knocking sound, such as one from YourMechanic. They will be able to better determine what direction you should go.

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