The Hazards of Coasting in Neutral on a Downhill Slope?
3 Answers
Coasting in neutral on a downhill slope can damage the transmission. The specific impacts are as follows: 1. Inability to supply oil normally: When an automatic transmission vehicle is shifted into neutral (N) while driving, the oil pump in the automatic transmission will not be able to supply oil normally for lubrication, causing the internal components of the transmission to heat up and leading to complete damage. 2. Increased fuel consumption: Coasting in neutral does not save fuel; sometimes it even consumes more. This is mainly related to the working mode of electronic fuel injection engines. Electronic fuel injection engines can determine the amount of fuel injection based on the computer program. If coasting in neutral is selected, the computer will put the vehicle into idle mode, and the engine will still inject fuel.
I learned this the hard way when I used to drive trucks. Coasting downhill in neutral sounds fuel-efficient, but it's actually extremely dangerous. Without engine braking to slow you down, you're relying solely on the brake pads to do all the work. On longer slopes, the brake pads start smoking, and by the time you want to slow down, the brakes have already failed. That time I almost crashed into a mountain wall—just thinking about it still gives me chills. Manual transmission cars have it even worse, as it's easy to burn out the clutch plates. And with modern fuel-injected vehicles, coasting in neutral actually consumes more fuel since the ECU has to inject extra fuel when RPM drops below 1000. It's both life-threatening and wallet-draining.
Never coast downhill in neutral with an automatic transmission. The transmission oil pump is driven by the engine, and oil pressure is insufficient when in neutral. Dry grinding of metal gears can easily lead to overheating and failure. I've repaired many cases of major transmission overhauls caused by this. The key issue is loss of speed control - you simply can't make turns when needed. Last year, a client crashed into guardrails driving like this; only the airbag deployment saved their life. Coasting in gear allows engine braking, making it ten times safer than neutral coasting.
