What Causes the Clicking Noise When Starting an Automatic Transmission Car?

[McDiana]

Automatic transmission cars produce a clicking noise when starting due to internal transmission issues and excessively low engine RPM. Internal Transmission Issues: Excessive wear creates gaps, leading to play during startup, which results in the clicking noise. Excessively Low Engine RPM: Insufficient output torque may cause gear dragging, potentially resulting in abnormal sounds. During rapid acceleration, when engine RPM rises extremely quickly, the transmission may experience a shock during the shift from 1st to 2nd gear. When heavily pressing the throttle to raise RPM to 5,000-6,000 or higher, the transmission must abruptly reduce RPM from 5,000-6,000 to 2,000-3,000 during gear shifts to stabilize engine speed, creating this impact. Maintenance Methods: Replace transmission fluid and perform comprehensive transmission maintenance. Additionally, avoid aggressive driving to prevent accelerated transmission wear. Another important note: regardless of gear shifting operation, always use the foot brake to completely stop the vehicle first.

[ZacharyRose]

I often tinker with my car, and encountering a clunking noise when starting in automatic mode is quite common. Most of the time, it's due to wear on the drive shaft universal joint, which is responsible for transmitting power. Over time, the gap increases, causing a clunking sound when accelerating. Brake pad sticking is another reason, especially after humid weather. If the car is parked overnight, the pads can stick to the rotor, resulting in a noise when releasing the brakes. Another possibility is aging or loosening engine mounts—if the rubber blocks are worn, they can wobble. Insufficient transmission fluid can also cause a jerky feeling when shifting gears and starting. I recommend not delaying and checking the drive shaft and brake system promptly. Otherwise, it could worsen into serious issues like a broken axle or brake failure. Regular cleaning of brake pads and topping up fluids can prevent this, and it's best to start smoothly without sudden acceleration.

[VioletMarie]

In the past, I heard a clunking sound when starting my car, which made me nervous and worried about an accident. A friend told me it might be the brake pads sticking, especially common after parking in a garage. I suspect worn universal joints could also cause this, producing noise under increased load during acceleration. Loose suspension components might lead to instability and sudden clunks. From a safety perspective, this can affect handling, making it more dangerous during turns or at high speeds. I believe it's crucial to visit a repair shop immediately for inspection rather than saving money and waiting for major repairs. For daily parking, avoid holding the brake pedal down for too long; release it gently a few seconds before starting to reduce sticking issues. Vehicle maintenance is a key step in ensuring safety for yourself and others.

[DelAndres]

When dealing with car issues, automatic transmission starting noises are quite common. The most frequent cause is wear in the driveshaft universal joint, where excessive clearance leads to a clunking sound under heavy starting load. Brake system sticking often produces similar noises. Another possibility is aging or loose engine mounts, where deteriorated rubber causes excessive movement. Insufficient transmission fluid can also cause rough shifting and impact noises during starts. I recommend early inspection of the drivetrain components to prevent system damage. For operation, focus on smooth acceleration rather than sudden throttle inputs to prolong component life. Regular fluid level checks can prevent many minor faults from occurring.