What Are the Causes of Transmission Noise?
3 Answers
The causes of transmission noise include: 1. The oil pump produces noise due to excessive wear or improper hydraulic oil level (too low or too high); 2. The torque converter generates noise due to damage to the lock-up clutch, guide wheel one-way overrunning clutch, etc.; 3. Noise from the planetary gear mechanism; 4. Noise from shift execution components. For fault diagnosis and troubleshooting, check the hydraulic oil level of the automatic transmission. If it is too high or too low, adjust it to the normal level. Use a lift to raise the vehicle, start the engine, and check the location and timing of the noise in the automatic transmission under neutral, forward, and reverse gears. If there is continuous noise in the automatic transmission in any gear, it is usually caused by the oil pump or torque converter. In this case, disassemble the automatic transmission for inspection, check whether the oil pump is worn, and whether there is a large amount of friction powder in the torque converter. If abnormalities are found, replace the oil pump or torque converter. If the automatic transmission only produces noise while driving and is silent in neutral, it is likely due to noise from the planetary gear mechanism. In this case, disassemble the automatic transmission and inspect each component of the planetary gear set for signs of wear, check for broken gears, wear or sticking of the one-way overrunning clutch, and damage to bearings or thrust washers.
I've encountered the issue of abnormal noises from the transmission quite a few times. The most common causes include aging or worn bearings, especially the input and output shaft bearings, which produce a humming sound during high-speed operation; gear damage is another major culprit, such as worn gear tooth surfaces or cracks, resulting in rattling noises during gear shifting; there's also synchronizer failure—this component is responsible for smooth shifting and produces metal clashing sounds when damaged; additionally, insufficient oil or contaminated oil leading to poor lubrication increases internal component friction; worn clutch plates can also cause abnormal noises, particularly during starting, acceleration, and deceleration. Safety comes first—if you hear these noises while driving, it's best not to delay and head to a professional repair shop immediately. Otherwise, it could lead to the entire transmission failing, costing thousands to fix. Regular maintenance can prevent such issues, such as changing the transmission fluid every two years.
As someone who frequently drives long distances, I find transmission noises quite annoying. There could be several reasons: first, a damaged bearing, which sounds like a buzzing noise and is more noticeable at high speeds; second, gear issues, such as wear or breakage, causing harsh grinding sounds when shifting; third, problems with the synchronizer or clutch, leading to poor engagement; also, insufficient or dirty oil, resulting in poor lubrication; or foreign objects entering the transmission, like small debris jamming the parts. These not only affect driving comfort but also increase safety risks—imagine a failure on the highway, that would be terrible. So I always remind myself not to ignore it. During regular car washes, I simply check the oil level, and if I notice any unusual noises, I send it for inspection immediately to avoid skyrocketing repair costs.
