What Causes Abnormal Engine Noise During Cold Start?
2 Answers
Abnormal engine noise during cold start can be caused by: 1. Engine oil not reaching operating temperature; 2. Worn valve rocker arms leading to excessive valve clearance; 3. Throttle valve contamination due to accumulated sludge and carbon deposits. Solutions: 1. Clean throttle valve carbon deposits; 2. Check for abnormal battery voltage. Causes of knocking sounds during cold start include: 1. Malfunctioning fuel tank vent valve; 2. Fluid impact inside the return pump; 3. Partial blockage in the fuel filter. An engine is a machine that converts other forms of energy into mechanical energy, including internal combustion engines, external combustion engines, jet engines, electric motors, etc.
I've driven quite a few cars and encountered abnormal noises during cold starts. The most common issue is with the timing chain—either the chain has stretched or the tensioner has failed. In winter, when starting cold, the loose chain can make a loud clattering sound. Another frequent cause is low oil pump efficiency or oil that's too viscous, leading to insufficient lubrication and abnormal metal friction noises. It could also be due to excessive valve clearance or bearing wear, where the contraction of cold components in the morning makes the vibrations more noticeable, producing a creaking sound. I remember once hearing this kind of noise in a friend's car and immediately suggested he check the oil pressure and chain tension. It turned out replacing the tensioner fixed the issue, saving him from a major engine overhaul. Regular maintenance and using the correct oil grade are crucial to prevent the noise from worsening and affecting the engine's lifespan. Those with good DIY skills can refer to the manual for diagnosis, but complex problems are best handled by professionals. While it might seem like a minor issue, delaying repairs can lead to serious trouble if the chain skips a tooth.
