What Causes the Clicking Sound Outside the Car When Shifting an Automatic Transmission?

[OFinley]

Automatic transmission shifting with abnormal sounds can be attributed to the following reasons: 1. Large valve clearance when the engine is cold: Poor lubrication during the transition from cold to hot engine state may cause noise when shifting, lasting about 3 minutes, which is a normal phenomenon. 2. Problems caused by parking on a slope: If the P (Park) gear is engaged first before applying the handbrake when parking on a slope, an external force due to inertia will cause the vehicle's weight to be entirely borne by the P gear, resulting in noise when shifting; if the handbrake is applied first, the handbrake bears the force, and no noise will occur. 3. Transmission issues: Wear and tear on the transmission, loose drive shaft, differential wear, wear on the transmission's output shaft, gear wear, or malfunctioning shift mechanism require immediate attention at a 4S shop or professional auto repair shop for technician repair.