What Are the Hazards of Long-Term Engine Idling?
2 Answers
The hazards of long-term engine idling include: 1. Wasting fuel, which is the most direct impact; 2. Generating a certain amount of carbon deposits. Due to the low engine speed and low air intake efficiency during idling, combustion is not very complete, making it prone to carbon deposits. More importantly, the carbon deposits produced cannot be expelled and will continuously accumulate in the cylinders and intake passages, significantly accelerating the rate of carbon buildup. Idling refers to an operating state of the engine, generally when the throttle is completely released, and the engine runs naturally. Simply put, it is the operating state when no throttle is applied. The idle speed varies for each vehicle, and even for the same vehicle, the idle speed differs between cold and warm conditions. The idle speed is much higher when the engine is cold, which is controlled by the engine computer to achieve a high idle speed during cold starts. The purpose is to rapidly increase the water temperature to reach the normal operating temperature, reduce engine wear, and minimize harmful exhaust emissions.
I used to frequently let the engine idle while driving, especially in traffic jams or while waiting for someone, and found it quite harmful. First, fuel consumption increased significantly—the engine was running but the car wasn't moving, wasting fuel. My monthly fuel expenses were hundreds more than usual. Second, carbon deposits easily formed. Long-term low-speed operation led to incomplete combustion, causing residue buildup in the cylinders and on the fuel injectors, which several times resulted in engine shaking and reduced power. I also noticed insufficient lubrication, as the oil circulated slowly, accelerating wear on components like piston rings and bearings. A mechanic once told me this could lead to an earlier need for major repairs. Additionally, cooling was inadequate—staying at high temperatures for too long with poor fan efficiency once nearly caused overheating and a breakdown. Overall, developing the habit of turning off the engine during short stops can protect the engine and save money.
