What are the consequences of revving the engine in neutral?
2 Answers
Revving the engine in neutral can subject the moving parts of the engine to significant inertial forces, affecting its reliability and lifespan. When the car is in neutral, the engine does not output power. In this state, revving the throttle causes the engine speed to rise sharply, forcing moving parts such as pistons and connecting rods into rapid acceleration, which generates substantial acceleration and subjects them to high alternating loads. The forces on the pistons, piston pins, connecting rods, connecting rod bolts, and crankshaft will exceed those under normal operating conditions. Additionally, the sharp increase in engine speed during revving can lead to inadequate lubrication at friction points, increasing the risk of cylinder scoring or bearing seizure. Prolonged revving in neutral can also result in severe incomplete combustion. If unburned fuel-air mixture ignites outside the cylinders, it may cause the vehicle to catch fire. Incomplete combustion also promotes carbon buildup, which can clog the catalytic converter, leading to abnormal high temperatures. These elevated temperatures may cause wiring to ignite, with potentially serious consequences.
I've been driving for over twenty years and have revved the engine in neutral a few times before learning my lesson. It causes the engine to spin wildly without any load, and as the RPMs climb, the fuel gauge plummets—it's just a complete waste of gasoline. I've also noticed that prolonged high RPMs like this increase wear on internal engine components like pistons and bearings, shortening their lifespan. Once, I tried it with a brand-new car, and the noise was so loud the neighbors complained. Later, a mechanic mentioned there might have been minor damage. Honestly, unless you're intentionally trying to clean carbon deposits (and even then, it's better to do it while driving), I really don't recommend it. When idling at a red light, it's more eco-friendly to just turn off the engine—developing good habits can save you a lot of money. Oh, and some older car models might even overheat from this, leading to more serious issues. Safety first, right?
