What Causes Engine Noise After the Car Is Turned Off?
2 Answers
Engine noise after the car is turned off can be caused by the following reasons: 1. Loose screws at the three-way catalytic converter interface: Thermal expansion and contraction after turning off the engine can make the noise more noticeable. Solution: Tighten the screws. 2. Damaged charcoal canister solenoid valve: This can easily cause the fuel tank to deform and produce noise. Solution: Replace the charcoal canister solenoid valve. 3. Poor operation of the starter's solenoid: The solenoid is used to engage the starter gear with the engine flywheel. After turning off the engine, the solenoid needs to disengage. If it operates poorly, it can easily cause noise. Solution: Replace the solenoid. 4. Uneven engine cooling causing noise: After driving for a while, the engine temperature becomes very high. When the engine is turned off, the temperature of various components decreases, and thermal expansion and contraction cannot occur uniformly. This inevitably leads to gaps between internal metal parts of the engine, causing friction and noise due to cooling contraction.
Every time I drive long distances or drive aggressively, I hear a ticking sound from the engine area right after turning off the car. It's actually quite common, so there's no need to worry too much. This mainly happens because the engine components expand due to high temperatures during operation and then contract rapidly as they cool down after shutdown, creating thermal expansion and contraction noises. Particularly around the catalytic converter, thin metal sheets may slightly deform and make sounds as they cool—I looked it up, and this is considered normal. However, pay attention if the noise is unusually loud, lasts too long, or is accompanied by other issues like smoke or strange odors, as it could indicate a cracked exhaust pipe, a turbo fan not stopping completely, or bearing wear. I once had a weird noise from a loose exhaust in my old car, and it only went away after repairs. For safety, it's best to have a technician inspect the exhaust system and engine components during your next maintenance check to ensure everything is fine. Warming up the engine for a few minutes before driving and maintaining smooth driving habits can also help reduce such noises.
