What Causes the Noise When Starting an Automatic Transmission Car?

[LaFrank]

Automatic transmission car starting noise may be caused by brake pads in the break-in period, particles such as gravel entering the car interior, or improper driving. The following is a detailed introduction about automatic transmission cars: Overview: Automatic transmission cars generally refer to vehicles that use an automatic transmission (AT) to adjust speed. While driving, the control system of the automatic transmission automatically selects the appropriate gear based on the engine speed and load, replacing the driver's subjective judgment of timing and gear shifting operations. Others: Automatic transmission cars usually use a hydraulic transmission device to replace the mechanical clutch of manual transmission cars, so there is no clutch pedal. When the engine speed is low, the torque transmitted by the fluid is limited and insufficient to propel the car forward.

[MacVincent]

I've been driving automatic transmission cars for over 20 years and often encounter strange noises during startup. Common causes include: wear and tear on the transmission torque converter or internal component damage, leading to unstable oil pressure that produces friction sounds or clicking noises when the engine starts; rust or foreign objects in the brake system, such as rusted brake discs after parking, causing sharp grinding sounds during initial movement; aging and loosening of suspension bushings, resulting in rattling vibrations; abnormal drive shaft clearance or differential issues, noticeable during low-speed rotation. I recommend first testing the startup method on a safe, flat road—gently pressing the accelerator to accelerate slowly—to see if the noise disappears. If it persists, don't delay; immediately visit a professional shop to check the transmission fluid level. Replacing the fluid might solve minor issues. A major repair could cost thousands, but ignoring the problem could lead to accidents. Safety is paramount when driving, so never skimp on these inspection costs.

[TuckerLee]

As an ordinary car enthusiast, I find the noise during automatic transmission starts quite annoying. Common issues include: rusted brake discs that squeak when starting after overnight parking; loose suspension components like shock absorbers or control arms that rattle during initial vibrations; insufficient or aged transmission fluid causing dry grinding of internal gears, resulting in metallic clashing sounds; and loose engine belts that creak when the load increases during startup. My personal approach is to first identify the sound type: friction noises often indicate brake issues, while impact sounds may point to suspension problems. Simply trying to start under different road conditions with reduced load can help. If necessary, top up the transmission fluid, but if the noise persists for more than a week, it's best to send the car for repairs to prevent minor issues from becoming major ones. Driving involves the safety of the whole family, so timely inspections save both peace of mind and money.

[AdrielDella]

I always prioritize driving safety, and unusual noises when starting an automatic transmission vehicle should never be ignored. These sounds typically originate from transmission issues—such as worn clutch plates causing a low growl during startup due to oil pressure fluctuations, foreign objects stuck on brake discs producing sharp squeals after parking, or cracked suspension bushings resulting in clattering noises from the initial jolt. It's advisable to immediately pull over and identify the sound's location: front-end noises likely indicate brake problems, while central undercarriage sounds often point to transmission issues. Don't wait for severe damage—promptly refueling and replacing components can prevent greater risks, as sudden failures at highway speeds are extremely dangerous.