Why does the Volkswagen engine still make noise after turning off?
1 Answers
Volkswagen cars may still produce engine noises after turning off due to the following reasons: 1. Cool-down noise from the catalytic converter: The normal operating temperature of a catalytic converter ranges between 400-800°C. After turning off the engine, its operation gradually stops, and the temperature begins to drop, causing the internal metal components to expand and contract due to heat, resulting in abnormal noises. 2. Turbocharger cooling noise: Under normal circumstances, exhaust gases can reach temperatures of 600-700°C, accelerating the friction-induced heat from the rapidly spinning turbine. After turning off the engine, the heat expansion and contraction become quite noticeable, leading to abnormal noises. 3. Uneven engine cooling: After driving for a period, the engine temperature becomes very high. When turned off, the cooling and contraction rates of various components differ, inevitably causing friction between internal metal parts due to cooling contraction, which produces abnormal noises.