Why does the car keep making noise after being turned off?

[MacRuth]

If the car keeps making noise after being turned off, it may be due to the cooling sounds of the catalytic converter, exhaust pipe, etc. Here is more relevant information: 1. Turbo cooling sound: Under normal circumstances, the exhaust gas temperature can reach 600-700°C, accelerating the friction-generated heat from the rapidly spinning turbo. After turning off the engine, the thermal expansion and contraction can be very noticeable, resulting in abnormal noises. 2. Abnormal noise caused by uneven engine cooling: After driving for a while, the engine temperature is very high. When turned off, the temperature of various components drops, and thermal expansion and contraction may not occur uniformly, inevitably leading to friction between internal metal parts due to cooling contraction, causing abnormal noises. 3. Poor operation of the starter solenoid: The solenoid is used to engage the starter gear with the engine flywheel. After turning off the engine, the solenoid should disengage. If it malfunctions, it can easily produce a "rattling" noise.

[Clara]

I've been driving for over a decade, and it's quite common for the car to make noise after turning off the engine. In most cases, it's the cooling fan working—the engine gets too hot and needs to cool down automatically for a while before stopping. Just wait a couple of minutes, and it'll quiet down. However, if the noise persists or sounds like a clicking noise, you should be alert. It could be a stuck relay or a short circuit. I once encountered a situation where the fan kept running, and the mechanic said the electrical components had aged and burned out. It cost a few hundred bucks to replace the part. Safety-wise, don’t ignore unusual noises. Delaying repairs could lead to battery damage or even a fire risk. My advice is to clearly identify the source of the noise after turning off the engine. If it doesn’t stop after a few minutes, take it to a professional shop for inspection.

[OLucille]

From experience, it's important to take the issue of noises after turning off the car seriously. If the fan runs for too long, it indicates poor engine cooling, possibly due to dust blockage or fan motor failure. I've seen cases where this burned out wiring, resulting in expensive repairs. The fuel system can also make noises—for example, a normal exhaust pressure relief hum is fine, but if the sound is sharp and persistent, you should check for relay or switch sticking. Don't delay on safety; immediately turn off electrical components and wait. If the noise doesn't stop, call a mechanic to avoid fire hazards. Regular maintenance, such as cleaning dust and inspecting wiring, can help prevent such issues.

[RobertLynn]

I don't think this is hard to deal with. First, listen to the type of sound when the car is turned off: fan noise is mostly normal cooling; beeping abnormal sounds may indicate a fault. Wait five minutes to see if it stops. If it doesn't, check if the fan is stuck, and blown fuses are also quite common. Last time, I replaced the fuse myself and solved the problem, spending little money to save big trouble. Loose battery terminals can also easily cause noise, and fixing them will help. If you can't handle it yourself, going to the shop for repairs is quick and reassuring, don't push yourself too hard.