Why is the noise loud during cold start of a car?
3 Answers
It is normal for a car to produce loud noise during cold start because after parking, the engine oil inside the engine will automatically flow back to the oil pan. During the next cold start, the oil will slowly return from the oil pan to the vicinity of the cylinder head. Different grades of engine oil have different characteristics, and their low-temperature startability and high-temperature anti-wear and adhesion properties also vary. The viscosity of engine oil is inversely proportional to temperature. When the engine is cold, the oil viscosity is higher. If the selected oil is too thick, it will impose additional losses on the starter motor, battery, etc. The hazards of an excessively cold engine include: 1. The temperature of the air-fuel mixture entering the cylinder is too low, degrading the quality of the combustible mixture, making ignition difficult or combustion delayed, leading to a decrease in engine power; 2. Unvaporized fuel washes away and dilutes the oil film on the surface of parts, exacerbating wear and tear.
Hey, I just figured out why my car makes such loud noises during cold starts—it's like a rock concert! The root cause is that the oil thickens at low temperatures, leading to inadequate lubrication, which causes engine parts to squeak or clatter. Additionally, worn or loose belts might produce a piercing screech, especially common in older cars. I've noticed it's worse in winter—never force acceleration before the engine warms up to avoid excessive wear. Actually, regular synthetic oil changes can help, and belts should be checked annually—replacing them is a permanent fix. Don't let small issues escalate; just get it checked at a repair shop, and you'll surely enjoy a quiet ride again.
Having repaired countless cars in the workshop, the most common issue causing loud cold-start noises is high oil viscosity in cold weather, leading to increased friction sounds from metal components. Next is severely worn belts slipping and squealing nonstop, or potential failures in the fan or water pump. Don't overlook exhaust system leaks—those sounds are even harsher. I recommend owners first inspect belt conditions themselves—if cracked, replace immediately. Don't delay; minor noises may signal major risks. A professional shop's diagnostic tools can pinpoint the issue. Proper maintenance ensures smoother engine starts.
