What Causes Engine Noise During Cold Start?
2 Answers
Engine noise during cold start may be caused by issues such as a faulty carbon canister purge valve, secondary injection system malfunction, or electric vacuum pump failure. Engine noise could also result from excessive engine load intensity. The reasons for engine noise are as follows: 1. Noise occurring within half a minute after cold start that disappears afterward is mostly due to thermal expansion sounds from the catalytic converter. 2. Significant noise during cold start is often caused by wear, elongation, or loosening of the timing belt/chain, or loss of tensioner functionality in chain-driven systems. 3. Air conditioning belt friction noise - if the sound only occurs when the AC is on, it may be caused by friction in the AC belt.
The engine noise when starting a cold car is likely due to insufficient oil warming. Engine oil thickens at low temperatures, reducing lubrication efficiency, which increases friction in components like pistons and valves, causing creaking sounds. This is common in older vehicles or during cold winter mornings. Check if the belt system, such as the alternator belt, is too loose or worn—excessive looseness can produce screeching noises. Also, inspect the valve mechanism; hydraulic lifters may make noise if they lack oil. I've encountered this issue before, and replacing the belt with a higher viscosity oil solved it. Regular oil maintenance is crucial to prevent accelerated engine wear and increased fuel consumption. Warming up the car for a few minutes before long trips can help, but for a permanent fix, a professional inspection of the wiring and wear conditions is necessary. Ignoring it long-term can turn minor issues into costly major repairs.
