How Long Does It Take for an Engine to Cool Down After the Car Is Turned Off?
4 Answers
After the car is turned off, the engine generally takes 3-5 minutes to cool down. Below is an introduction to the working principles and cooling technologies of engine cooling: Working Principles: Liquid cooling involves circulating fluid through pipes and passages in the engine. When the fluid flows past the high-temperature engine, it absorbs heat, thereby lowering the engine's temperature. After passing through the engine, the fluid then flows to a heat exchanger (or radiator), where the heat in the fluid is dissipated into the air. Cooling Technologies: Commonly used cooling technologies include convective cooling, film cooling, transpiration cooling, ablative cooling, radiative cooling, and thermal insulation.
I've been driving for over a decade, and engine cooling is quite a tricky thing. Last time after driving on the highway, I got home and turned off the engine, but the hood was too hot to touch. You need to wait at least ten minutes, and for turbocharged cars, you should wait at least twenty minutes before daring to open the hood. If it's a car that's been baking in the summer sun, the cooling fan won't stop running for at least half an hour. I remember once being in a hurry and adding coolant to the radiator before it had cooled enough, and the antifreeze sprayed out and warped the bumper. Now I've learned my lesson—as soon as I turn off the ignition, I open the windows for ventilation and take some time to organize the trunk to pass the time.
That day, while picking up my daughter from school, the coolant temperature warning suddenly came on, so I quickly pulled over and turned off the engine. Watching the digital temperature gauge drop from 100°C to 80°C took about seven or eight minutes, but it took over forty minutes for the engine to cool down completely. Aluminum engine blocks dissipate heat faster than cast iron ones, and turbocharged cars take even longer to cool down. Once, when driving my friend’s old Jeep Cherokee, the heat in the engine bay didn’t dissipate even after half an hour of shutting it off. Now, during hot weather, I make sure to turn on the air conditioning first when taking my pet out to cool down the car, so my dog’s paws don’t touch the scorching exhaust pipe.
I've studied cooling systems when playing with car modifications. The intercooler gets so hot to the touch that it takes about 15 minutes to cool down. For a regular 2.0L naturally aspirated engine, it takes approximately 25 minutes to drop from operating temperature of 90°C to 60°C, and at least an hour to cool completely. Aluminum alloy engines dissipate heat faster. Once after a track day, a mechanic directly poured cold water on the engine block - the sizzling sound was just like grilling meat. After the cooling fan stops, it's best to wait another two songs' worth of time before opening the hood.
