Does Idling a Car for 20 Minutes Cause Damage?
4 Answers
Idling a car for twenty minutes can cause certain damages to the vehicle. Main Damages: The primary damage is that prolonged or frequent idling can easily lead to carbon buildup inside the engine cylinders, and the throttle may also be affected. When carbon deposits accumulate to a certain extent, the vehicle's power performance will decline, and over time, it can easily cause engine wear. Fuel Consumption Impact: Additionally, prolonged idling increases fuel consumption. A significant portion of fuel consumption during vehicle use is due to idling. This is why vehicles often have lower fuel consumption when driving on highways—there is minimal idling time, and the engine operates in its optimal state, resulting in higher fuel efficiency.
It depends on the specific situation. I often idle with the AC on while waiting for people, and it's really not a big deal for short periods. But if it exceeds 15 minutes, you need to be careful. Long-term low-speed engine operation can easily lead to carbon buildup, especially on the back of the intake valves in direct injection models. Too much carbon buildup can increase fuel consumption and cause rough cold starts. If the oil temperature doesn't rise, it can actually increase wear, and condensed water dripping from the exhaust pipe can corrode the muffler. During my last maintenance, the technician mentioned a car that frequently idled for half an hour to charge, and within six months, the catalytic converter got clogged, costing nearly 5,000 yuan to repair. If you really need to run the AC for a long time, it's better to lock the car and take a walk to a nearby convenience store.
As someone who frequently visits construction sites, I always keep a folding chair in my car and have really looked into this issue. Twenty minutes of idling is most damaging to the battery—the alternator continuously charging an already full battery can cause the electrolyte to overheat and evaporate. Once, I left my car fridge on while idling for an hour, and the battery swelled up and died. Also, older cars need to watch out for overheating—my colleague’s 2008 Camry once overheated because the radiator fan got stuck while idling with the AC on. Now, my habit is to turn off the engine and open the windows if idling for more than 10 minutes. If I really need the AC, I shift to neutral and rev to 1,500 RPM—this ensures enough pressure for the water and oil pumps without worrying about the transmission overheating.
Having repaired cars for twelve years, the most extreme case I've seen is a ride-hailing driver idling for five hours daily to charge. Here are some facts: 1. Low-temperature operation wears piston rings more than high-speed driving; 2. Carbon buildup in the intake manifold of turbocharged cars accelerates turbo bearing wear; 3. Oxygen sensors in fuel-injected cars are easily contaminated by unburned gasoline. However, twenty minutes of idling isn't a major issue—just remember to take a high-speed drive monthly. Pay special attention to water dripping from the exhaust pipe; excessive dripping indicates incomplete combustion, which can lead to spark plug fouling during idling. German cars require extra caution, as their direct injection systems are more sensitive to carbon deposits.
