Why does the engine sound louder when it gets cold?
2 Answers
The reasons why the engine sound becomes louder in cold weather are as follows: 1. Thickened gear oil: Due to the cold weather, both the engine lubricating oil and the gearbox gear oil become thicker and more viscous, causing unstable idling. The idle speed must be increased, making the engine sound louder at idle. 2. Increased gaps: Similarly, due to the cold weather, apart from the thickening of lubricating oil, the gaps between the cylinder and piston also increase, leading to more compression leakage and worsened combustion. More fuel must be added to handle the previous load, resulting in a louder sound when driving. 3. Uneven mixing: In cold weather, the combustible mixture does not mix as uniformly as before, leading to incomplete combustion and reduced power. To achieve the original speed, drivers unconsciously press the accelerator harder, which naturally makes the sound louder. 4. Mechanical noise: Due to the low temperature, the gaps between the engine and chassis components increase, producing mechanical noise. As a result, the overall vehicle noise becomes noticeably louder than before.
Recently, my car has been the same way. When it's cold, the engine noise becomes noticeably louder. This is mainly because the engine oil thickens at low temperatures, reducing its fluidity during cold starts and increasing friction between engine components. Especially in northern regions where temperatures drop below minus ten degrees Celsius, the rumbling sound at startup is particularly obvious. Rubber belt components like the alternator belt and A/C belt harden in the cold, producing squeaking noises. The exhaust pipe also makes metallic contraction sounds due to temperature changes. If the car is over five years old, worn engine mounts can make vibrations more noticeable. Don't worry too much—after warming up for five minutes until the coolant temperature rises, things usually return to normal. However, if the noise gets louder after warming up and is accompanied by metallic knocking sounds, you should immediately check for issues with the piston rings or connecting rod bearings.
