Internal combustion engines are very slow to cool and for good reason. After a good drive, the engine can reach temperatures that are as high as 1,400°F (760°C). Of course, there are cooling mechanisms within the engine, such as anti-freeze, oil, outside air, and water.
On average, it will take a minimum of half an hour for an engine to completely cool after reaching its standard, driving temperature. That’s assuming that everything is fine with the engine and nothing else is wrong with the vehicle.
If your engine is overheating, it may take longer for the engine to settle to a nominal temperature, especially if you let the needle climb well into the red before you shut the vehicle down.
Does the Engine Size Make a Difference?
Different engine sizes do make a difference. A V8 will take more time to cold down over a four-cylinder engine, assuming that both engines were able to reach their optimal, driving temperature.
It’s a simple matter of size. With larger engines, you have a lot more metal and surface area and that extra metal takes a little longer to cool. When we say ‘cool,’ it’s more along the lines of reaching a temperature that would no longer raise the needle.
For instance, you can walk outside on a cool day and still detect warmth in the engine, even if it hasn’t run in two hours. However, if you cranked it up, the temperature gauge would be at the bottom, as if you waited ten hours instead of two.
Do Other Factors Determine Cooling Rate?
There are a lot of other factors that will determine how slow or fast your engine cools down after you cut the ignition.
- Ambient temperature
- Wind
- Where you’re parked
- Whether or not the hood is up
- How many aluminum parts are in there
- Size of the radiator
- Airflow
- Grill form and shape
The ambient temperature definitely makes a difference. Your engine is going to cool down faster when it is 24°F outside than when it is 95° outside. Winter is definitely the time of the year when your engine will cool down the fastest.
It makes a difference where you’re parked as well. Did you park it in full sunlight, partial sunlight, or full shade? Shade alone can make a 10°F to 20°F difference in how cool the ambient temperature is around your vehicle.
If you need your engine to cool down faster, pop the hood. It allows more ambient air to get in and around the engine, cooling it faster. It’s especially useful on very windy days, where you can get airflow from below, above, and through the grill.
Aluminum shrugs off heat much more efficiently than iron. That’s why aluminum is so often used in the over. When you want to bake something but don’t want that food to get burned on the bottom, you use aluminum. The more aluminum when into your engine’s manufacturing process, the quicker it will cool.
The size and efficiency of the radiator matter as well. Just because you cut the engine off, doesn’t mean those fluids stop flowing immediately. There is also gravity to deal with and how cool the fluid is when it originally passes through.
Airflow goes hand-in-hand with the open hood and what kind of grill you have. Some people love to get those intricate grills that allow for more eye-candy than the common sense that comes with a proper airflow through the grill, electric fans or clutch fans, and over the engine.
How Does the Cooling System Work?
You have multiple cooling systems in your vehicle, so it’s not just the radiator. You have the radiator fluid, airflow, oil, and the tubes and fans that deliver it.
The coolant circulates throughout the engine, absorbing the heat that’s generated from the combustion process, delivers, and dissipates that heat once it reaches the radiator. Your fans and the airflow that floods through the grill and from underneath also serve the purpose of being a kind of secondary cooling method.
Although oil isn’t a coolant, its lubrication of critical engine parts acts as a secondary form of cooling, especially since it reduces friction, which also increases heat.
So ultimately you have three different materials that are working to keep your engine cool. For the most part, it all works as it should, until it doesn’t, which can happen from time to time.
What Causes Overheating?
There are a lot of different things that can malfunction and force your engine to start overheating.
- Any kind of clog in the system
- Faulty thermostat
- Leaking radiator
- Water pump failure
- Cooling fan failure
Anything that disrupts the flow of your coolant creates a problem because it is no longer absorbing the heat from the engine and transferring it to the radiator, at least not as well.
A faulty thermostat could cause the valve to remain closed, even when the temperature reaches a level that is supposed to cause the valve to open, so that radiator fluid can flow through.
Leaking radiators and tubes are the most common problem. You’ll start overheating long before you lose all of your radiator fluid, as the amount of fluid necessary to absorb and radiate heat is lower and no longer as effective.
Water pump failures are the worst, as the pump is often located close to the timing belt and the upper intake manifold, pulleys, belts, alternators, and so much more often have to come out in order to change it.
Cooling fans are simpler. When they fail, that lack of airflow can be just enough to overheat your vehicle, even if the coolant is flowing normally. Electric fans are the prices to replace, with clutch fans being cheaper but more difficult to replace.
If your car is overheating
Overheating engines are a common problem in vehicles and, if it happens to you, it’s best to pull over and let the engine cool for at least 30 minutes before you continue on. You also need to get it parked or to a shop as soon as possible.
Always be very careful before you work on your car after you have driven it. Even if its not overheating it is still very warm. And the temperature varies so you should wait at least 30 minutes before you touch anything in the engine bay. If its overheating you should wait at least one hour, but hold your hand in safe distance and feel it its warm from distance. You should always do this even though you have waited for the car to cool down.