Why does the car's engine speed increase but the vehicle speed doesn't?
2 Answers
When the car's engine speed increases but the vehicle speed doesn't, it may be due to clutch and transmission failure or torque converter failure. Below are detailed explanations of the specific reasons: Clutch and Transmission Failure: The main reason is issues with the clutch and transmission. The clutch acts as an intermediary for power transfer between the engine and transmission. If the clutch friction plates are slipping, it can result in a loss of power. If the clutch is functioning properly, the possible causes could be problems with the output shaft or the meshing gears of the transmission. Torque Converter Failure: Automatic transmissions have a torque converter, which serves a similar function to the clutch. During power transfer, the engine's flywheel drives the pump impeller, creating a vortex that moves the turbine. Since the turbine is connected to the transmission output shaft, if there is insufficient power output, the most likely cause is a torque converter failure.
I often encounter this situation when repairing cars. The driver says that when they step on the gas pedal, they only hear the engine roar, but the speed doesn't increase. The most common cause is clutch slippage, especially in older manual transmission cars. When the clutch plate is worn out, it's like a bicycle chain slipping—no matter how fast the engine spins, the power doesn't reach the wheels. In automatic transmissions, it could be due to belt slippage or valve body sticking, and the transmission fluid will definitely have a burnt smell in such cases. Also, don't underestimate the tires. Severely low tire pressure or driving with the spare tire still on can make the tires unable to roll effectively, rendering the engine's effort useless. Once, a car was revving at 4,000 RPM but only reaching 60 km/h. When I opened the hood, the air filter was clogged like a rag—insufficient air intake naturally left the engine powerless.
