What Causes the Abnormal Noise During Cold Start?
3 Answers
The reason for the abnormal noise during cold start is: the internal gears of the starter lose lubrication, affecting the timely return of the gears. When starting the engine, the starter rotates to drive the flywheel, which in turn starts the engine. At this point, the engine's speed is driven by the starter, so the engine speed is lower than the starter speed. When the engine speed exceeds the starter speed after starting, the operator manually turns off the ignition switch to cut off the power, and the starter shuts down. Due to dirt inside the starter and ineffective lubrication, the flywheel forces the starter to rotate at the engine's speed. Since there is a speed difference between the two, this causes the starter to produce noise. This noise will only stop when the starter reaches the same temperature as the engine. However, in severe cases, the noise may occur every time the engine is started. To eliminate this noise, cleaning and maintaining the starter or replacing the starter is necessary.
Cold start instant abnormal noise, my car often has this issue, usually it's the clicking sound caused by poor contact between the starter motor gear and the flywheel. In cold weather, thicker engine oil leads to poor lubrication, making the noise more likely. Or it could be the belt aging and loosening, causing a screeching sound from friction. It's important to promptly check if the engine oil level is sufficient and if the viscosity is correct, otherwise the starter motor may wear out and replacing it is expensive. My experience is to have the mechanic check the belt tension during every maintenance service; if it's loose, it needs tightening or replacement. Another possible cause is insufficient oil in the hydraulic lifters, resulting in a tapping noise that stops after a while, but don't delay fixing it or the lifters may fail. Remember to let the engine idle for a minute after a cold start before driving to reduce wear. If you can't check it yourself, go to a professional shop—safety first. Ignoring it may turn a small issue into a major repair.
I'm quite familiar with cold start noises. As someone who loves tinkering with cars, the common issues I encounter are worn belt tensioners or timing chains stretching, causing squeaking or rattling sounds. Especially in winter when oil thickens and chain lubrication becomes insufficient. Try checking the belt tension yourself - if it's too loose, that might be the culprit. Don't underestimate timing chain issues; delaying repairs can lead to skipped teeth and engine damage. Some car designs have pulleys positioned in ways that are more susceptible to cold weather effects. In cold conditions, check your oil viscosity - 0W or 5W grades have better low-temperature flow. Replacing a tensioner doesn't cost much, and if you're handy, you can do it yourself to save time and money. If the noise disappears when the engine warms up, it confirms it's a cold-state issue, but don't take it lightly. Also, exhaust manifold leaks can cause noises - a simple weld inspection can identify this.
