Starting an automatic transmission car in any gear other than “Park” or “Neutral” can lead to serious damage to the transmission, engine, and even the vehicle itself. This is because the transmission is designed to be engaged only when the engine is running, and starting it in gear creates a dangerous situation where the engine is forced to overcome the resistance of the transmission and the wheels.
Here’s a breakdown of the potential risks⁚
Potential Damage
- Transmission Damage⁚ The most common consequence is damage to the transmission itself. When the engine starts in gear, the transmission is forced to engage under high load, which can strain and damage the internal components. This can lead to slipping, grinding noises, and ultimately, transmission failure.
- Engine Damage⁚ The engine can also be damaged due to the increased strain of starting in gear. The engine may stall or even backfire, potentially causing damage to the pistons, connecting rods, and other components.
- Vehicle Damage⁚ If the vehicle is on an incline, starting in gear can cause it to roll forward or backward unexpectedly. This could lead to a collision or other damage to the vehicle.
Why This Happens
Automatic transmissions are designed with a torque converter, which acts as a fluid coupling between the engine and the transmission. When the engine is off, the torque converter is disengaged, allowing the transmission to be shifted freely. However, when the engine starts while the transmission is engaged, the torque converter is suddenly forced to engage, creating high stress on the transmission and engine.
Safety Precautions
To avoid these risks, always ensure your automatic transmission car is in “Park” or “Neutral” before starting the engine. It’s a simple habit that can save you a lot of trouble and expense in the long run.
Exceptions
Some modern vehicles may have features that allow starting the engine in “Neutral” or even “Drive” with the brake pedal depressed. These systems are designed to prevent the vehicle from rolling when the engine is started. However, these features should only be used in accordance with the vehicle’s owner’s manual. Always consult the manual for specific instructions on starting the engine in these situations.
Conclusion
Starting an automatic transmission car in any gear other than “Park” or “Neutral” is a dangerous practice that can lead to serious damage. Always put your transmission in the correct gear before starting the engine to ensure the safety of your vehicle and yourself.