CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Idiling a car for heat for 40 minutes one time ok?

Is it OK to idle a car for heat for 40 minutes one time? Car is 2000 Corolla with 60k miles.

How come a gas generator can run 24 hours straight but a car cannot?

It’s ok. I guess a car could run 24 hours (with enough gas). But why?

+1 to texases’ comment.
A one-time episode of long idling is inconsequential.
What is much more important is how diligently the OP actually maintains his Corolla.

As to cars, yes, you could run the engine for 24 hours, as long as you had enough fuel.
Should you?
No
Can you?
Yes

In fact, one of my work colleagues told the story of his wife returning home one afternoon from a shopping expedition, during a torrential rainstorm. The next afternoon, when she couldn’t locate her keys, she realized that–in her haste to get out of the rain–she had left their Chevy Nova idling in the driveway for about 20 hours. And–yes–the car continued to run well for the next 3 years that they owned it.

Who said a car cannot idle 24 hours straight? It’s been done many times by mistake.

Yes, it is ok in an emergency or temporary convenience as a car can easily be driven for 40 minutes or longer at one time, but carbon monoxide and inefficiency in a system that was meant to move a car not be a central heating system means, there is a better way. It can be done many times over, as long as the car “lasts”. It’s just too bad you don’t use a dedicated heater if possible that doesn’t loose it’s value and cost so much more to maintain and fix. But, fear not…it’s perfectly fine.

Why the 40 minute mark ?
When I’m waiting 30 minutes for my son …in the snow…I idle for 5…wait 10 or so for the heat to dissipate, the heat up again for about 5…depending on the weather and rate of heat loss.
That 40 min is overkill, you got all the heat it put out and are only putting more of the same…you can NOT gain any more heat retention time, it’s all the same after you turn it off.

As long as the engine is working correctly, idling for long periods would do no damage other than normal wear and tear and burn up the gas in the tank. But if something went wrong with the engine unattended, that could cause problems, some very expensive to fix. Like if the radiator cooling fan gave up the ghost, the engine could well overheat enough to warp the cylinder head.

I used to drive a patrol car for a friend of mine who owned a security company. I never turned the car off for 8-10 hours at a stretch and that’s they way the owner wanted it. He had a contract to be at a certain location at a certain time and we always were. I think the local police department did the same thing. I always thought it was a waste but I didn’t own the company. BTW…that patrol car never had problem one but it was well cared for and never missed a shift in the 2 years I drove for them.

At work many vehicles run a majority of the day without going anywhere, I have not seen any negative effects.

Be very aware of WHERE you are when you do this.
Even a carport could perhaps be too enclosed and trap CO.
Hot exhaust starts fires in grassy areas.

Modern engines properly operating can idle without harm right up until the gas tank runs dry.

In the days of carburetors, long term idling was not recommended. Carbureted engines run “dirty”, producing a lot more carbon than modern engines, and extended idling could contribute to excess carbon buildup in the cylinders and on the sparkplugs, but modern engines produce far less carbon at idle than carbed engines did.

Carbon is basically a byproduct of insufficient oxygen-to-gasoline ratios, insufficient cylinder heat, and/or insufficient time in the power stroke for the gasoline droplets to fully burn.

Modern engines mist the gas to a much finer mist, allowing the use of less gasoline and enabling much more complete combustion of the much finer droplets during the limited-time that a power stroke provides at idle speed, and modern engines monitor what’s going on to a far greater degree than old engines did, adjusting the fuel metering appropriately. Modern engines don’t have a carbon buildup problem at idle.

It’s not going to hurt it a bit. Emergency vehicles spend a lot of their lives idling and while admittedly they usually get better maintenance than your car probably does, they last a long time. Years ago on one of my first jobs, which was as a delivery driver, I used to let my vehicle idle for sometimes 8 hours at a time. Many days a week. And these were vehicles that others had mostly thrown away. No ill effects. Oh, and they were carbureted too, no fuel injection back in those days. The worst I incurred was when my car stalled one time apparently and the battery was pretty low from the blower motor, radio, etc. on without the engine running.

One worry (besides theft) about leaving a vehicle unattended to idle is there’s no one watching the gauges, so if something does malfunction, the vehicle will idle until destruction if not noticed. That and carbon monoxide concerns if the vehicle is idling in an enclosed space, and possibly a danger of fire if you’re parked on some tall grass, etc. Oh, and you’re needlessly wasting fuel, polluting the environment, yada yada…

We live in a cold area, many drivers go shopping and leave their locked cars idling. I did the same when living I the Arctic.

Yes, you need more frequent maintenance when you do this repeatedly.

If your doing it in the snow, make sure the tail pipe stays clear. Otherwise you can be killed from carbon monoxide poisoning.

It’s OK if you are near it or in it so that it doesn’t try to self-destruct without you being right there to stop it. As far as the portable generator goes; if it isn’t running you won’t get electricity from it. You wouldn’t run it for forty minutes without using it for something. Idling your car may not be good for the smog system, which means catalytic converter and oxygen sensors. The converter goes cold during idle and doesn’t work as efficiently. You still may never have any problems doing anything you want to do.

My truck has an inverter and AC outlet in truck bed. It only runs obviously, if the truck is idling and is great for power tools. The motor is otherwise, nothing special. I think if the manufacturer did not make cars that could easily idle for extended periods, they would have a hard time selling them to families with teenage drivers. When my kids used our cars, they sometimes seemed to have used much more gas then the mileage would indicate. As long as both were in one piece, we didn’t ask too many questions.

@pleasedodgevan2: I might have to disagree with what you said about the converter getting too cold when idling–I can monitor the cat’s temp with the scan tool I have. While it is definitely warmer when driving, it’s still showing a temp of over 900 degrees internally when idling, based on the sensor data I get. A quick Google shows “light off” is about 550 degrees for these. From a cold start, I see the cat reach light-off temp in maybe 20 seconds.