Why Does an Automatic Transmission Car Make Noise When Shifting Gears?

[StephenLee]

Here are the reasons why an automatic transmission car makes noise when shifting gears:1. Shifting gears without stopping completely: When parking, if the car is not completely stopped before shifting to P gear, the P gear lock hook inside the transmission will hit the gear, making a clicking sound.2. Incorrect operation sequence when parking on a slope: For an automatic transmission, the P gear relies on the lock hook to hold the gear in place to keep the car stationary. When parking on a slope, you should first apply the handbrake and then shift to P gear, allowing the handbrake to bear the downward force of the car.3. Worn transmission gears: The transmission is a precision component, and the gears best reflect its precision. However, due to tight meshing, wear is inevitable. Over time, larger gaps will form between the gear teeth, resulting in noise when shifting gears.

[VanMaximus]

My old car recently made a clicking metal grinding noise every time I shifted gears, which scared me into thinking the transmission was about to fail. After taking it to my trusted repair shop, they found out it was just a loose shift cable connector. The mechanic said the plastic clips tend to age and crack over time. He also checked the transmission mount bushings and found the right one had flattened and cracked, causing the engine to shake and jolt the transmission during gear shifts. These rubber components need attention every three to five years for replacement. He advised against using high-pressure water jets to spray the engine bay during car washes, as water ingress into the shift mechanism can cause rust and noise. If you hear a hissing sound, it might be a cracked transmission vacuum line, which needs immediate attention.

[RubyDella]

Last week, while driving my friend's automatic car, I heard a gear grinding sound from the chassis the moment I shifted the gear lever to D. The mechanic said that although automatic transmissions don't require clutch pedals, the gear lever is connected to the gear position switch inside the transmission. If the contacts of this switch wear out, poor contact can occur. While using the diagnostic computer to read the fault codes, he also taught me a little trick: after a cold start, hold the brake and wait for the RPM to stabilize before shifting gears. If the abnormal noise disappears at this point, it's likely due to the transmission fluid being too viscous or the fluid level being low. Additionally, poor contact in the brake light switch can interfere with the shift lock, causing a clicking or sticking sound. He recommended ensuring the foot brake is fully depressed before shifting gears.

[DelJesse]

When I was modifying my car, I encountered a hissing sound when shifting gears in the automatic transmission. It turned out the transmission oil filter screen was clogged. This part is hidden inside the oil pan, and when too much metal debris and sludge accumulate, the oil pressure becomes unstable. During gear shifts, the valve body doesn't move properly, producing a whistling sound like pressure release. The repair shop used a circulation machine to replace twelve liters of oil before it quieted down. Additionally, if the exhaust pipe hanger breaks, the exhaust system will rattle and shake during gear shifts, sounding like transmission noise but actually not. Those who have modified their exhaust systems should especially check this point, as metal fatigue tends to occur after about three years.