What Causes Abnormal Noise in Idle Engine?
2 Answers
The causes of abnormal noise in an idle engine are: 1. Excessive wear of the cam causing tappet jumping during operation; 2. Impact between the rocker arm head of overhead valves and the valve top; 3. Excessive carbon buildup in the valve guide; 4. Detachment of the valve spring seat; 5. Damage to hydraulic tappets or tappet cylinders; 6. Aging or loosening of engine mounts. The maintenance methods for car engines are: 1. Regularly change the oil and filter; 2. Use lubricating oil of appropriate quality grade; 3. Regularly clean the radiator; 4. Regularly replace the air filter, oil filter, and fuel filter; 5. Maintain good crankcase ventilation and clean it periodically; 6. Regularly clean the fuel system.
I drive an old car, and recently there's been abnormal noise from the engine at idle, with a particularly noticeable squeaking sound. I've checked some materials and consulted with my mechanic friend. This could be due to the aging and slackening of the drive belt, causing significant friction noise; or it might be the bearings of rotating components like the water pump or alternator wearing out, leading to uneven rotation and a buzzing sound. Another possibility is an issue with the oil pump, where insufficient lubrication pressure increases mechanical part friction, resulting in a clattering noise. Loose or leaking exhaust pipe joints can also produce abnormal noises—I once encountered a metallic hissing sound from a gap. Additionally, malfunctioning hydraulic valve adjustment can cause idle noise, so a thorough inspection is necessary. It's advisable to regularly change the oil and check the belt. If any noise is detected, promptly visit a professional repair shop for diagnosis to prevent minor issues from turning into major repairs. Safety first.