What Causes the Engine to Make a Thumping Sound?
4 Answers
Engine thumping sounds may be caused by cold start abnormal noise and carbon canister solenoid valve operation noise. Below are detailed explanations of the causes and corresponding solutions: Cold Start Abnormal Noise: Many people hear a "clicking" noise from the engine compartment during a cold start. This "clicking" noise occurs because the oil pump has not yet fully built up oil pressure during a cold start, causing insufficient lubrication of various components. Solution: Under normal circumstances, the clicking noise will disappear after the engine has been running for a while. Carbon Canister Solenoid Valve Operation Noise: The function of the carbon canister solenoid valve is to open the solenoid valve between the carbon canister and the intake manifold after the engine starts, allowing the gasoline vapor adsorbed in the carbon canister to enter the cylinder along with air for combustion. This not only reduces emissions but also lowers fuel consumption. This component may also produce a clicking sound during operation. Solution: This is a normal working phenomenon and does not require any action.
I've been driving an older car and have encountered engine knocking sounds quite a few times. Each time it happens, I need to carefully investigate the cause. Common issues include worn connecting rod bearings or loose water pumps causing mechanical collision sounds, especially noticeable during acceleration or uphill driving. Lack of or deteriorated engine oil can worsen this situation, potentially leading to more severe failures such as engine cylinder scoring. I recommend immediately checking the oil dipstick level and changing to fresh oil if necessary. If the sound persists, take it to a professional repair shop for diagnostic equipment testing—don't ignore it as repair costs could escalate significantly. Regular maintenance is crucial—using high-quality oil and filters can prevent many abnormal noises. Above all, safety first—if you hear strange noises, stop driving immediately rather than pushing through.
My new car has been driven for less than two years, and I heard a knocking sound after starting it the day before yesterday, which made me quite worried about driving safety. After researching online, I concluded that it might be knocking noise caused by a misfiring cylinder or a fuel pump issue. The sound is more noticeable on the right side of the engine, accompanied by slight vibrations. I tried checking the spark plugs for carbon buildup but didn’t dare to disassemble them randomly, as a beginner could easily make mistakes. Fuel consumption seems slightly higher, and performance has dropped significantly. I recommend going directly to a 4S shop for a comprehensive inspection—they can connect to the computer to read fault codes and handle the issue faster. For daily use, pay attention to fuel quality and avoid using low-grade fuel to prevent nozzle clogging. Addressing the noise promptly will give you peace of mind.
As a DIY car repair enthusiast, I often tinker in the garage to solve engine knocking noises. The most common causes are loose timing chains or clogged oil pumps causing metal impact sounds, located in the middle section under the hood. I usually start by using a stethoscope tool to locate the sound source and check the oil viscosity—if it's too thick, changing it might help. For chain issues, adjusting the tensioner can be tried. Fixing minor problems yourself saves money, but inaccuracies might damage more parts. The noise is prominent at idle and may affect overall operation smoothness. Major repairs like piston wear require experts to avoid mistakes, but it's quite fun to learn new skills while working. Keeping the chain clean and regularly lubricated reduces risks.
