What Causes Abnormal Noise When the Engine Just Starts?

[OOscar]

It is caused by a fault in the carbon brushes inside the starter motor. Below is an introduction to the reasons for abnormal noise when the engine just starts: Reasons for abnormal noise: Over time, the engine belt may age and slip, producing a squeaking sound; loose engine mount bolts can cause improper engine support installation. If the engine mount bolts are loose, you can locate and tighten the specific screws yourself. If the belt is loose or aged, causing a buzzing sound, you can replace it with a new one. If there is a fault in the carbon brushes inside the starter motor, you should seek professional help at a 4S shop and avoid disassembling the engine yourself. Maintenance awareness: With high mileage and prolonged use, the engine valves and hydraulic components will experience a certain degree of wear. When the wear becomes excessive, abnormal noises may occur. To resolve this issue, the cylinder head needs to be disassembled to replace these components. A way to mitigate this problem is to change the oil regularly. Avoid overusing engine oil, as excessive use can degrade its lubrication effect, thereby accelerating the wear of valves and hydraulic components. During cold starts, due to the viscosity and poor fluidity of the oil, operational noise may occur in the short term, and slight noise may be heard when moving parts come into contact.

[JaxsonMarie]

My car makes strange noises right after starting, and after checking, I found out it might be due to a loose timing chain or worn tensioner. The chain makes abnormal sounds when the oil pressure is insufficient. The problem is more noticeable during cold starts in winter because low temperatures cause increased component gaps and more metal friction. I recommend checking the oil quality and change intervals, and it's best to check the dipstick monthly. Additionally, a loose belt might also cause squeaking sounds. If the noise is only slight, there might be no rush to repair it, but if the sound gets louder, head to a professional shop immediately to avoid costly repairs, such as damaging the engine block, which would be a big hassle. Long-term neglect could also affect fuel efficiency and safety, so early troubleshooting is more worry-free. Remember not to drive on wet roads to prevent accidents.

[GiselleRose]

Once when I started the car, I heard a rattling sound from the engine, which startled me. The mechanic said it was an issue with the valve lifters or hydraulic components—insufficient oil pressure during cold starts causing metal-to-metal contact and abnormal noise without proper lubrication. After changing the engine oil and maintaining regular servicing, the situation improved significantly. Such noises are common in older vehicles; if it occurs in a new car, it might indicate improper factory assembly, requiring adjustment of the crankshaft position sensor. I ignored it twice, which led to a noticeable increase in fuel consumption and nearly left me stranded on the road. I recommend recording the sound with your phone to show the mechanic and paying attention to engine temperature regularly. Pre-warming the engine for 10 seconds before starting can reduce the noise. Avoid cutting corners by taking it to small repair shops, as the problem may recur.

[McAlaina]

Engine noise upon startup is most commonly caused by wear on the starter motor gear or belt friction sounds, which are louder when the engine is cold. I've tried checking it myself by opening the hood to locate the sound: if it's coming from the front, it might be due to belt aging; if from the rear, check if the oil pump is functioning properly. New drivers shouldn't panic—buy some high-quality engine oil, replace it, and try starting the engine a few times to see if there's any change. Also, a loose timing chain can produce a rattling sound; if not repaired promptly, it can lead to chain skipping, and in severe cases, require an engine overhaul. Remember to avoid overloading or rapid acceleration to extend component lifespan. The safest approach is to regularly visit a maintenance shop to check belt tension.