Internal combustion engines utilize flammable fuel and operate at thousands of revolutions per minute, so it’s no surprise that the system can get hot. If you’re curious about the time it takes for the car to cool off, chances are you’re either changing the oil or engine parts, or you’ve ended up stranded with an overheated engine. We’re here to tell you how long to wait, depending on the situation and tasks you want to achieve.
Cool Down After Overheating
The engine operates in the same line as a human body, with mechanical organs made out of iron and steel, computer units being the brain, engine block as its heart, and rubber tubes as blood vessels. If any part starts malfunctioning, the entire system suffers the consequences.
Coolant is the most common cause of overheating. The radiator is located at the very front of the engine to absorb the air that the car has to go through as a result of drag. This rapidly cools the coolant fluid, that is pushed through the system by a pump.
Problems with the coolant can be as serious but are generally manageable without lasting consequences. The temperature gauge on the dashboard should stay in the middle, 90 degrees Celsius, or 200 Fahrenheit. It’s normal for it to start climbing slightly during a prolonged uphill drive, but in general, any deviation should be a cause for concern.
Should the pump malfunction, coolant leak, or fan fail to cool efficiently, the car will inevitably overheat. As the coolant reaches its boiling temperature it will begin to evaporate and build pressure inside the system, resulting in the pressurized radiator cap releasing it in the iconic cloud of white mist.
Despite reaching its highest potential temperature, the cooling process for an overheated engine is one of the shortest: around 30 minutes. The reason why it doesn’t take too long is that the goal is to get back to driving and not work on any of the parts. However, you might have to top up coolant if you suspect too much is lacking.
Exercise patience and do not unscrew the radiator cap until the engine’s heat cannot be felt anymore. If you unscrew the cap while the coolant is still hot, the built-up pressure will burst out and cause serious burns!
Adding room temperature coolant to a hot system can be harmful to the engine, as sudden temperature change can cause it to crack. Having driven a lot of old Skodas, overheating turned from a rare anomaly to a common occurrence for me. My method involves raising the hood to let the engine cool off more quickly, and if need be, prepare the coolant by placing the bottle at a safe spot where it can absorb some of the heat.
Getting it even slightly warmer reduces the temperature difference with the engine, and makes it that much safer and quicker to top up and get back on the road.
Cool Down for an Oil Change
Oil is the most important of engine fluids. Coolant problems will gradually increase the temperature until the safety systems force you to stop before any lasting damage. If you’re not paying attention to oil levels and change cycles, a problem can pop up suddenly, and destroy the engine in a matter of a minute.
If the engine warning light comes on, stop as soon as you can, wherever you can safely do it. This is not a problem that can wait for the next rest stop – every revolution of the engine can be it’s last.
Cooling down the engine for an oil change is interesting in that you cannot do it if the engine is hot, but you also cannot do it when it’s completely cold. Oil changes viscosity with temperature. The hotter it is, the easier it flows. There are two ways to get to an optimal temperature:
- If you have driven the car to its running temperature, let it cool for 30 minutes.
- If the engine is completely cool, start it up for a couple of minutes.
In the first case, you’re letting the engine cool enough to let you get to the oil filter without burning yourself, while in the second you’re getting the oil up to temperature so it can flow more easily. The times are just estimates and can be affected by the ambient temperature, so work within your conditions and don’t worry too much about it. Just be careful not to spill hot oil on yourself!
Cool Down for a Mechanical Procedure
When replacing or inspecting parts, the amount of time you should wait can vary. One or two hours is okay for most tasks, but if you’re planning on opening the engine block or do a major diagnostic test, leave it overnight. The thing I’ve learned the hard way is not to check just the temperature of the part you’re working on, but all of the parts around it. Gloves will protect the hands, but forearms are generally exposed and can get burned.
Remember that engine parts are made of different materials that dissipate heat differently. This is especially true for hoses, which cool much more quickly than the metal parts they’re attached to.
If you’ve skimmed through and just want the numbers, then the short answer is 30 minutes for overheating and oil change, a few hours for repairs. However, I strongly advise reading through the guide and learning more about what causes the engine to overheat, and how to safely approach the problem. Keep reading our guides and articles if you’re interested in learning more useful maintenance and repair tips!