Is it harmful to rev the engine in neutral?
2 Answers
Revving the engine in neutral is harmful and can shorten the engine's lifespan. When the car is in neutral, the engine operates without any load. Suddenly pressing the accelerator in this state subjects some internal engine components to significant inertial forces, which can reduce the engine's longevity. If the engine is revved in neutral right after startup, it can accelerate engine wear. From a mechanical perspective, even though the gear is in neutral, the engine's power still drives the transmission's input shaft via the clutch, keeping it in an operational state. In this scenario, pressing the accelerator affects components like the input shaft, intermediate shaft, and constant-mesh gears, which adjust according to the engine's RPM, while the output shaft and synchronizers remain stationary. Prolonged revving in neutral or coasting long distances in neutral can damage the transmission, leading to issues such as input shaft bearing wear, synchronizer gear wear, burning, and transmission noise.
I've been driving for decades and often see beginners enjoying revving the engine in neutral, which actually harms the car. Running the engine at high RPMs without load is like a person running in place without moving forward—it increases internal component friction, leading to accelerated piston ring wear and cylinder overheating. Over time, fuel consumption also rises sharply. I remember a friend's car once suffered significantly reduced engine lifespan due to frequent neutral revving, eventually costing thousands in major repairs. I suggest avoiding this habit, especially at red lights, as it can also affect idle stability and throttle body contamination. If you encounter unusual noises or vibrations, it's best to visit a professional repair shop promptly for inspection.
