How Long Does It Take a Car to Cool Down?

Engines tend to get extremely hot during and after driving. But exactly how long will it take for them to cool down?

How Long Does It Take an Engine to Cool Down After Driving?

Normally, an engine completely cools down after 30 to 45 minutes. However, several factors can still affect this range. 

The average cool down time for an engine can be affected by the weather condition, car size, engine specifications, and other factors.

While this might be the case, you can still expect a huge drop in engine temperature after 30 minutes. 

Why Do Engines Get So Hot?

The combustion process is over 2,000 degrees during each piston’s power stroke, and this heats up the inert nitrogen that makes up over 70% of the air in the cylinder. As the nitrogen expands, it drives the piston down. This heat, once it has done its work, must be carried away to prevent damage to the cylinder walls, the pistons, and the heads.

When the engine oil surpasses the boiling point of water that is created during combustion and bypasses the rings into the crankcase, the water becomes steam that is carried out of the crankcase along with the other vapors by the positive crankcase ventilation system (PCV). This can reduce sludge build-up in the crankcase.

How Long Does It Take a Car to Cool Down After Overheating?

Regardless of whether or not your vehicle overheated, it should take about 30 minutes for the engine to cool down. By this time, the engine will still be hot, but there will already be a significant drop in its overall temperature.

The exact time it takes for an engine to cool down completely can vary. Some might take one to two hours, while others can take more than four hours to revert to their ambient temperature, depending on how hot or old it is outside. In the winter, the engine will cool off very rapidly for obvious reasons. You can look at the coolant temperature gauge.

Note that an engine’s heat reduction rate is directly proportional to the temperature difference between the environment and the engine. 

If the temperature of the engine is close to the temperature of the environment as it cools down, convection cooling will drop significantly. 

The material from which the engine is made can also impact cooling time. For instance, aluminum block engines tend to cool down much faster than iron block ones. 

The only downside to having aluminum block engines is that they are more prone to heat damage. 

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: If you’re thinking of checking the coolant level, squeeze a radiator hose to see if it’s pressurized. If it is, don’t remove the radiator filler cap. As an aside, it’s a good idea to squeeze the radiator hose when the engine has been shut off all night so you can familiarize yourself with the feel of the hose when there is no pressure in the cooling system.

A Quick Look at Cooling Systems

The cooling system is responsible for regulating engine temperatures. Current production passenger vehicles make use of antifreeze coolant to raise the boiling point of the water, which is 50% of the mix. The coolant also prevents corrosion of metal parts throughout the engine’s cooling system.

The coolant or antifreeze passes through the engine block and cylinder head where it picks up heat. The cylinder head is the hottest part of the engine that is cooled by antifreeze. 

The thermostat, when closed, causes the water to circulate through the heater core or bypass hose. When the thermostat opens, coolant is pumped through the radiator, where it gives up its heat.

The thermostat is cycling all the time when the engine is running, but it cycles very slowly as the radiator removes heat from the coolant. Only when the thermostat opens up will the water pump circulate the coolant through the radiator. 

Main Causes of Overheating

There are several reasons why your engine can overheat. Here are some of the most common ones. 

Low Coolant

Coolant or antifreeze is responsible for three things:

• Transfer heat from the engine to the radiator
• Protect the engine and cooling system from rust and corrosion
• Prevent freezing in cold climates

Coolant doesn’t magically disappear from the system. In most cases, little to no coolant is the result of cooling system leaks. 

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Coolant can also get old enough to lose its properties even without a leak. Old, worn-out coolant will allow an engine to overheat even if everything else is working the way it’s supposed to.

Water Pump Problems

The water pump circulates the coolant, and if the pump’s impeller is loose, rusted way, or if the reaction surface the impeller spins next to is cavitated, the water pump won’t move coolant as it should. The water pump can also leak and its bearings can fail, both of which can cause overheating.

Radiator Issues

Radiator problems, such as cracks and defective cooling fans, can prevent heat from being released into the air. Radiators can clog internally with rust and sludge and externally with plant material, dust, and dirt in vehicles like farm pickups that are driven a lot through tall grass.

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Thermostat Failure

While the thermostat can fail by sticking closed and cause overheating, the vast majority of thermostat failures cause the engine to run too cold because the thermostat is stuck open or opens too soon.

Repercussions of Driving an Overheated Vehicle

Overheating is one of the primary causes of engine failure and other issues. There are many cases where an overheated engine will run again after it cools down, but don’t expect a smooth drive anytime soon once this happens. 

Severe Engine Damage

Driving with an overheated engine can damage the head gasket, cylinder heads, and the engine block. Depending on the severity of the damage, you might need to get a complete engine replacement. 

Poor Vehicle Performance

If you get your vehicle running after it overheats, expect issues such as reduced power output, diminished efficiency, and poor fuel economy. 

Safety Risks

Driving an overheated vehicle is a lot like operating a loose canon. You’ll never know when it’ll break down, increasing the risk of getting into an accident.

It can leave you in dangerous situations, like getting stranded on a highway or on the side of the road under extreme weather conditions. 

How to Avoid Overheating Your Engine

Even with car care, prevention is the best medicine. By sticking to your vehicle’s maintenance schedule, you can ensure that all of your vehicle’s systems are running properly. 

Regular maintenance checks can also catch faulty parts or those that are nearing the end of their service life. 

It also pays to be vigilant. Unexpected scenarios that can damage your cooling system can arise anytime, so be sure to watch out for coolant leaks underneath your vehicle. 

How to Cool Down Your Engine

In the event that your engine temperature begins to overheat, here are some things you can do.

First, turn off the air conditioning to reduce strain on the engine. The next thing you should do is crank the heater and fan to full blast. This will carry heat away from the engine. 

Top off your cooling system with water or coolant to decrease engine temperature. However, keep in mind that this is only a temporary fix until you get to the nearest repair shop. 

It’s also a good idea to rev up the engine for air and water to circulate in the radiator.

Should the temperature continue to rise, it’s best to pull over and contact roadside assistance.