What are the effects of restarting a car that is already running?
4 Answers
If a car is frequently restarted while already running, it can cause damage to the starter motor, the starter engagement gear, and the flywheel ring gear of the engine. Occasionally restarting the car while it is running will not have any impact on the vehicle. Precautions when starting a car: When starting the car, it is important to observe the information on the dashboard, check if the tires and chassis are in normal condition, release the handbrake before starting, warm up the engine before driving, and shift from low gear to high gear. Modern cars generally use a push-button start system, which differs from the traditional mechanical key ignition method. Simply pressing the button can start or stop the engine, avoiding the hassle of losing car keys. When using the push-button start, it is necessary to press the foot brake to start the car. Specific hazards of restarting a car while it is running: When a car is "restarted," the flywheel ring gear at the rear end of the engine crankshaft will engage with the gear on the motor shaft again, causing unnecessary wear. The high-speed rotating flywheel ring gear engaging with the stationary gear on the motor shaft will inevitably produce a sharp metallic collision noise. The duration and frequency of "restarting" are the main factors that determine the abnormal wear of the flywheel ring gear and the gear on the motor shaft.
I've been driving for nearly twenty years and have seen many beginners make this mistake. Starting the engine while it's already running causes the starter gear to suddenly grind against the flywheel, wearing down the flywheel ring gear. It's like repeatedly yanking a taut rope—it will eventually snap. Doing it once in a while might not cause harm, but frequent repetition can lead to gear slippage, making the next startup jam. It also risks burning out the starter coil, requiring costly replacement. The battery drains significantly during ignition, and restarting wastes current unnecessarily, especially in winter when a weak battery increases the risk of stalling. To avoid unnecessary repair costs and extend component lifespan by over five years, develop the habit of checking the dashboard for rising RPM or listening for stable engine noise before turning the key again.
Over the years of car enthusiasm, I've experimented multiple times with restarting the engine while it's already running. This subjects the starter to additional impacts, doubling the gear-to-flywheel impact force and accelerating wear, especially in older models which are more sensitive. During ignition, the battery experiences peak current draw, and repeated operations waste power, shortening battery life and increasing the risk of winter dead-battery scenarios. Through discussions with fellow car enthusiasts, I've learned that some vehicles' starters fail with just a buzzing sound. I recommend developing the habit of checking dashboard indicators before exiting the vehicle. Beginners can install protective devices to avoid accidental damage-causing operations. Regular maintenance checks can also prevent such issues, saving you from troublesome roadside breakdowns.
Starting the car again after ignition causes the starter gear to forcefully clash with the flywheel, leading to increased wear. In the short term, this results in loud noise, while long-term effects include damage to the ring gear, causing slippage. Additionally, this operation discharges the battery unnecessarily, accelerating the risk of aging. Such practices increase maintenance costs, such as requiring an engine overhaul to replace the flywheel. I recommend listening to the engine sound or checking if the RPM stabilizes before starting the car daily, cultivating good habits to ensure safe driving without accidents.
