One of the most debated topics among drivers is about long idling.
Is it bad, will it damage the engine or does it all even matter are just some of the questions that are frequently asked.
In this article, we’ll try and shed some light on the whole topic and clarify the dilemma.
1. CAN EXCESSIVE IDLING DAMAGE A CAR?
To be more precise with this question: can excessive idling damage the engine?
The answer is no! With modern engines and with normal exploitation, no major damage will probably happen.
Emphasis on normal exploitation. If you leave your car idling for five or ten minutes at a time, that’s considered normal. Although even that is long in most situations.
But if you leave the engine idling for let’s say half an hour and do that on a regular basis, that’s considered extreme exploitation. This can certainly cause engine damage over time.
Besides this, problems with the coolant system, lack of oil in the engine, low-quality maintenance, etc. combined with long idling will certainly cause engine problems.
So, if you normally use your car and leave it idling for a long time now and then, you won’t suffer much damage in the long run.
It’s not a good habit nevertheless.
2. WHY IS IDLING BAD FOR LONG PERIODS OF TIME?
The answer is: long idling puts more strain on the engine, it’s bad for fuel consumption and is bad for ecology.
Long idling puts strain on the cooling system
The engine and all its systems are not mainly constructed for stationery work but for when the car is in motion.
Coolant systems are made to work with the best efficiency while air is going through the radiator. Yes, the coolant fan will lower the temperature while the car is idling, but it puts more strain on the system.
This goes double if you let the car idle for a long time in hot weather. Simply, the coolant fan can’t match the cooling capacity of the radiator. Besides that, the extra load is put on the alternator and then the engine because of frequent usage of the radiator fan.
Same story with lubricating. It’s of course much better when the engine has some revs because the oil flow is much better.
Besides this, lots of cars have oil radiators in order to additionally cool the oil down. Of course, when the car is in motion, the cooling is more efficient.
More fuel consumption over time
Lots of drivers see long idling as irrelevant to the overall fuel consumption. It couldn’t be further from the truth.
Yes, the fuel consumption is much lower when idling. But if done frequently and for longer periods of time, it can add up to a serious amount.
The main reason for this behavior is perhaps the notion that long idling is better than starting and stopping the engine all the time as well as avoiding a cold start.
Drivers want to avoid putting strain on the battery, starter, and other engine systems thinking that the overall gain outweighs the cost of fuel.
In my opinion and experience, the cost of a new battery and starter (in worst-case scenarios) is far less than the cost of all that fuel that is spent during years of long idling.
Of course, this is under the circumstance that the car starts properly and you don’t have to crank the engine for a long time.
Long idling damages ecology
Needless to say, more burnt fuel means more damage to Mother Nature.
Despite the fact that the pollution is probably less during idling than driving, if you do it for a long period of time, it adds up.
When the car is idling, it’s still polluting.
If you have ecology in mind, the best thing to do is to turn off the engine while waiting in traffic. Also, begin driving as soon as possible.
This is one reason, besides lowering fuel consumption, why start-stop systems were invented.
3. HOW LONG DOES IT TAKE TO CHARGE A BATTERY AT IDLE?
This question is asked, in most cases, when a flat battery problem occurs and you have to use jumper cables to start the engine.
If you want to learn how to use jumper cables, click here for a separate article on that topic or watch a tutorial on our YouTube channel.
Know to answer the question. Once you start the engine, about five minutes is enough to recharge the battery in order to be able to start the car again and drive normally.
It’s almost fully charged in about an hour or so.
In these cases best avoid long idling. Instead, start driving the car as soon as possible as it will recharge much faster. But if idling is necessary, best rev up the engine from time to time.
This data is valid under the circumstance that there are no other issues like car battery problems, alternator problems, starter problems, and so on.
One more important factor regarding this topic is the outside temperature. If it’s cold outside (like sub-zero temperatures) it takes somewhat longer for the alternator to recharge the battery.
4. HOW LONG IS EXCESSIVE IDLING?
This is highly debatable, but I would say anything over a minute in warm weather is too long. In cold weather, three to five minutes at most.
Exceptions would be situations like extreme cold and snow. If you have to defrost the car, clean the snow and drive through heavy terrain, you have to leave the car idling for some time.
This helps make the proper preparations and lets the engine warm up a bit.
Also, trying to get the maximum out of a cold engine in low temperatures is not recommendable. More on this topic, about a cold start, in a separate article that you can read by clicking here.
So, one of the main factors for answering this question would be the climate that you live in and the type of driving you’re going to do.
More cold, rough terrain or more extreme driving needs more idling.
With normal temperatures and normal driving, start the car, wait for about 30 seconds and begin driving at a normal pace.
5. SHOULD YOU LET YOUR CAR IDLE AFTER A LONG DRIVE?
No, with modern cars there is no need to do this but it is recommendable.
Especially if you’ve driven an uphill drive for a long time or drove at a faster pace like on a highway.
In these situations, turning the engine off immediately after stopping puts extra strain on the coolant system. The main reason is that hot, highly pressurized coolant stays dormant inside of it.
But when you leave the engine on for a couple of more minutes, the coolant keeps flowing through the radiator and gets additionally cooled down by the radiator fan.
Once again: modern engines will probably not cause problems if you turn them off after a long drive.
But it will certainly help to keep it running for a couple of minutes after you’ve stopped.
All in all, long idling is not good, except for a few extraordinary situations.
But perhaps the main reason and culprit for long idling is our own comfort.
For instance, one of the more unpleasant experiences is sitting in a cold passenger cabin in the winter. Leaving the car idling for at least five minutes fixes that very well.
Also, starting and stopping the engine in traffic all the time is seen as a nuisance, despite the fact that it isn’t complicated to do.
But every time you do this think about the overall damage it does. Both to your engine, to your home budget, and above all to Nature.
So, dear reader, the next time you look at your car in the driveway while it’s idling or you’re in traffic and won’t turn the engine off, please remember this article and turn that key to the OFF position.
With that little deed, you will do a decent amount of good over time.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com