How to Correctly Diagnose Engine Abnormal Noises?
2 Answers
Engine abnormal noises are common faults mainly in the crankshaft connecting rod mechanism and the valve train. There are two methods for diagnosing engine abnormal noises, namely the manual experience auscultation method and the instrument-assisted diagnosis method. The manual auscultation method involves technicians reproducing the abnormal noise by changing engine operating conditions and other measures, identifying the characteristics and patterns of the abnormal noise, and understanding the engine's operating conditions and fault symptoms when the noise occurs, thereby determining the location of the abnormal noise. This is currently the most common and primary method used. The instrument-assisted diagnosis method is employed because the accuracy of the manual experience auscultation method is relatively low. Therefore, some instruments and equipment are often used to assist in auscultation and analysis. Commonly used instruments mainly include stethoscopes, noise meters, vibration analyzers, etc.
Last time my car's engine made a strange noise, which gave me a scare, but I handled it calmly. I remember the sound was like drumming at idle, and upon checking, I found some wear on the piston connecting rod. The diagnostic steps are: first, find a quiet place to start the engine, don't drive, and carefully listen to where the noise is coming from. Knocking sounds are mostly in the upper part of the engine; squeaking could mean the belt system is loose or there's a water pump issue. I often use a long screwdriver as a "stethoscope," placing it at different points to amplify the sound and pinpoint the source. Also, check the oil level; if it's low, top it up immediately to avoid increased internal friction. Strange noises shouldn't be delayed, or else piston damage could lead to sky-high repair costs. Regular maintenance like frequent oil changes and checking belt tension can prevent small issues from becoming big problems. Engine health directly affects lifespan, so we car owners should develop the habit of listening for noises during cold starts every week—prevention is key.
