What Causes the Rattling Noise When Accelerating or Releasing the Throttle in a Passat?
2 Answers
Generally, the cause is related to the automatic transmission, which widely uses planetary gear mechanisms, resulting in abnormal noises. Bearing Noise: Typically, bearing noise is closely related to engine speed—the higher the speed, the louder the noise. Differential Noise: This type of noise usually becomes noticeable at speeds between 50–70 km/h. Due to variations in gear meshing surfaces, the noise is more pronounced during acceleration and significantly diminishes when the throttle is released. Hydraulic System Noise (e.g., Oil Pump): This noise is strongly linked to engine speed but unrelated to vehicle speed. At high RPMs, oil pump suction obstruction can lead to abnormal noises.
I've been driving this Passat for five years, and recently it's been making a creaking noise when I press and release the accelerator, like an old wooden door. Last week, I took it to the repair shop, and the mechanic pointed out three main issues: First, there's thick carbon buildup in the engine, especially around the throttle body, which is coated with sludge, causing the metal parts to scrape and make strange noises when the accelerator is used. Second, the intake pipe clip near the air filter box is loose, making the pipe rattle when the throttle changes. Additionally, the rubber mounts on the exhaust pipe hangers have aged and cracked, causing the exhaust to clunk around when accelerating. Now, I use a fuel additive every six months to clean the carbon deposits and tighten all the connections, which has helped a lot. Older cars need regular check-ups, or you might end up losing parts on the road someday.
