What Causes Abnormal Engine Noise When the Engine is Hot?
2 Answers
Abnormal engine noise when the engine is hot can be caused by excessive injector wear, excessive valve clearance, or piston slap. Below are the detailed explanations: Excessive Injector Wear: The injector has a needle that controls fuel injection. When the needle is excessively worn, the injector will produce abnormal noise. Excessive Valve Clearance: Excessive valve clearance in the engine can cause metal knocking noises and accelerate wear on the rocker arms and valve stems, making the noise persistent. Large valve clearance also reduces intake and exhaust volume, affecting engine power. Piston Slap Causing Abnormal Noise: Excessive clearance between the piston and cylinder; insufficient oil pressure leading to poor lubrication of the cylinder walls, causing cylinder wear and abnormal noise.
I've been driving this car for ten years and found that unusual noises from the engine when it's hot are usually due to insufficient or old engine oil. In hot weather, the lubricant becomes thinner, causing parts to rub and produce a buzzing sound. Like last time, after I changed the oil, the noise reduced. It's recommended to check the oil level during every maintenance and change the oil regularly. Another common issue is loose valve clearance or belts—thermal expansion can increase the gap, leading to a clattering sound. Don't ignore these minor issues. If the engine overheats while driving, it might damage the head gasket, leading to expensive repairs. I've experienced this myself and later installed a temperature gauge for monitoring. For safety, if you hear unusual noises, stop immediately to check the cooling system or visit a repair shop. In short, regular maintenance can prevent these problems.
