What Are the Causes of Abnormal Noises in CVT Transmissions?
3 Answers
Identifying abnormal noises can be divided into the following steps: 1. Noises heard during vehicle startup are generally related to suspension system issues: possibly caused by loose or damaged engine mounts. 2. Noises during vehicle turning may stem from steering or suspension system problems: as the vehicle tilts during turns, the suspension system deforms and participates in the motion. 3. Noises during smooth road driving could indicate brake system component failures: possibly due to loose or worn brake components, out-of-round brake drums, or uneven brake discs. 4. It might also be an issue with the bearings connecting moving and stationary parts: if it's a bearing problem, the driver can distinguish it by applying slight braking. If the noise remains unchanged during uniform motion with braking, it indicates a bearing issue.
I've driven quite a few CVT cars, and transmission noise is really nothing new. The most common cause is excessive wear of the steel belt or chain. If you frequently accelerate hard or carry heavy loads, the belt slips and rubs against the pulley, causing a squeaking sound. Transmission fluid is also a major issue—insufficient fluid level or degraded fluid quality leads to poor lubrication and friction noise, especially in cars that haven't had an oil change for a long time. Another culprit could be a faulty oil pump, where insufficient pressure causes noise, or a stuck hydraulic valve body affecting control. Loose components are also common, like unfastened screws that vibrate and create a buzzing sound. Prevention is simple: change the OEM fluid every two years or 40,000 km, drive smoothly without stomping on the accelerator, and get any unusual sounds checked ASAP. After all, CVT repairs are expensive, and delaying fixes could damage other components and compromise driving safety.
I'm quite familiar with the structure of CVT transmissions. The abnormal noise may originate from several points: Wear on the steel belt or chain is the most common issue – when the chain elongates, it can collide with the cone pulleys, producing a clicking sound. If the oil pump malfunctions, causing significant pressure fluctuations, it may be accompanied by a buzzing noise. Contaminated or insufficient transmission fluid is equally critical, as inadequate lubrication increases friction and noise. A faulty electronic control module might also interfere with the oil circuit, leading to unusual sounds. During diagnosis, pay attention to the type of sound: A sharp noise could indicate internal bearing damage, while a dull thud might suggest oil pressure problems. For maintenance, follow the manual for fluid changes and regularly use diagnostic tools to monitor the system. CVTs have unique designs, so avoid unauthorized engine power modifications. Don't ignore abnormal noises – early inspection can prevent more significant damage.
