How Long Can A Car Engine Safely Run On Idle?

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Do you have a remote start on your vehicle? Having this handy bit of technology can be helpful on cold days when you want to warm up your car before you go out in the cold. But have you ever thought about what might be happening while your vehicle is running on idle? If you have ever wondered how long a car engine can safely run on idle, we can give you the right answer. We researched car engines from a variety of professional sources so that you will know for sure.

Experts maintain that your car should never idle for more than thirty seconds to one minute. However, the reasons behind that advice pertain to conserving fuel and limiting the amount of exhaust. A car’s engine can idle indefinitely outdoors without any safety concerns.

Now that we know how long a car can run on idle, we’ll take a closer look at what is going on with your vehicle while it’s running in park. You might also be curious if it’s bad to idle the car if the air conditioner is on or if it’s bad to leave the car running overnight. Can idling damage your transmission? How long can a car sit without being driven? For the answers to these questions and more, read ahead in this post to see what our research has uncovered.

Car lined up at a heavily trafficked highway, How Long Can A Car Engine Safely Run On Idle?

Precautions to Take When You Idle Your Car for Long Periods of Time

As we indicated earlier in this post, there are no immediate safety concerns when you idle your car’s engine. However, idling your engine can cause some issues under certain circumstances. If you want to leave that engine running for more than a few minutes, then we suggest you follow these handy tips:

Make Sure Your Car is Well-Maintained

A vehicle that isn’t serviced regularly can have some of its parts at risk if your car sits idle for too long. Parts like timing belts, fan belts, and thermostats can be sent over the edge if they are already close to breaking. The vibrations from the engine when parked can trigger this if the car is idle too long.

Have Plenty of Gas in the Tank

Running out of gas is not only an inconvenience for you, but it isn’t the best thing for your vehicle. Any deposits or sludge in your fuel line can harm it.

Additionally, the fuel pump relies on the fuel to keep it lubricated and cooled. If it is still running without any fuel, it will damage it. So if you are in the practice of having your vehicle run for longer periods, make sure you’ve got plenty of fuel in your tank.

Be Outdoors!

Never idle an engine indoors. Car exhaust contains lethal amounts of carbon monoxide. This gas will lull a person to sleep and can potentially kill you.

Cars left running in garages can have carbon monoxide seep into the adjoining rooms of the house, putting all occupants at risk. This is especially dangerous if there is a bedroom above a garage and the engine is left idling at night. 

If you are going to idle your engine, make sure it is outdoors, where the exhaust fumes disperse quickly and easily into the fresh air. 

Is it Bad to Idle Your Car with AC On?

Under normal circumstances, your vehicle can idle with the air conditioner on indefinitely. Newer technology prevents damage from occurring and will help keep the car cool while you are waiting to get inside of it. 

There are some things you should be aware of, however. Earlier in this post, we mentioned that you should make sure you have enough fuel to idle an engine. Air conditioners will eat more fuel, thus making your tank run low quicker. If you plan on idling your car with the air conditioner on full blast for more than a few minutes, keep that in mind.

On really hot days, you can run the risk of your vehicle overheating with an idle engine. The air conditioner going makes the engine work more, making it even hotter.

Likewise, a vehicle with an older radiator, or one that is low on engine coolant, might also overheat in idle. So be aware of your vehicle’s condition, as well as be mindful of how the temperature outdoors might impact your idling engine.

https://www.istockphoto.com/photo/just-idling-gm172204155-275537

A car dashboard showing a low Rpm rate and increasing temperature

Is it Bad to Leave Your Car Running Overnight?

There is no impact on a gasoline-powered vehicle whether or not it is running idle during the day or all night. The limitations under each set of conditions will be the same. Just make sure the vehicle is well maintained, has a full tank of fuel, and is parked to idle outdoors.

A Stop idling sign installed in a post

Can Idling Damage Your Transmission?

Idling a car for long periods of time won’t damage the engine on its own. However, a vehicle overheating can undoubtedly damage the transmission and other vital parts under your vehicle’s hood.

Idling a car’s engine will keep it running without the benefit of forcing outdoor air into it. Not that this is a problem, necessarily. The engine fan will kick on when the engine is getting too warm to prevent it from overheating. 

But on really hot days, it might not be enough of a cooling device to keep it from overheating. And if your engine is too hot, your transmission will also be warming up.

Overheating is the bane of all parts under the hood of your car. This will make them wear out prematurely or even damage them to the point that they aren’t drivable. So if you are planning on idling your vehicle, be totally aware of the climate, the condition of your vehicle, and keep a close eye on it while it is idling. 

How Long can a Car Sit Without Being Driven?

A car can sit an indefinite amount of time without being driven. However, letting it sit too long might make it to where you won’t be able to start it up. Experts say that if you plan on leaving a car in one spot, you should have it started every few days and let it idle for at least ten minutes. This will keep the battery charged.

Cars that will sit for an extended period of time should have the battery disconnected. Tires will also go flat, so putting the car on blocks is a great idea, especially if you want to let the car sit for several months or more.

Finally, the fuel in the tank and the fuel line can be an issue if you are letting a car sit for a long time. We’ll address this particular item later in this post. 

How Long can Gas Sit in a Car?

Fuel, like anything in life, has a shelf life. When it’s in your gas tank, it will begin to deteriorate after about thirty days. If you plan on leaving your car idle, it’s best to have at least a quarter tank in it if you plan on keeping it parked for longer than that.

You should siphon the fuel out when you’re ready to start it up and replace it with a fresh tank. This is because the deterioration and moisture will make it harder to start your engine. This tainted fuel is also bad for your fuel line and engine.

The moisture that accumulates in a gas tank for too long will lead to corrosion. For this reason, JD Power recommends that you are careful not to let a vehicle sit this long without taking proper precautions, as well as injecting approved additives when it’s time to resume driving the vehicle. 

In Closing

Letting your car idle is safe, so long as you take certain precautions. A well-maintained and fueled vehicle can be idle for an extended period without risk of damage. However, be mindful of certain functions in your car, like air conditioning, that might make your engine run hotter while it idles. Hotter outdoor temperatures will also make the temperature of your engine rise, increasing the risk of overheating. Please pay close attention to the environment that your car is idling in, and never let it idle inside a closed space. Drive safe!

If you found this post on vehicle engines to be helpful, we believe you’ll enjoy reading the following automotive posts:

How Hot Does A Combustion Chamber Get In A Vehicle? [The Answer Might Surprise You!]

Do Exhaust Tips Change The Sound Of Your Car Or Truck?

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