What Causes the Buzzing and Resonance in a Prado?
4 Answers
Reasons for resonance and noise during car braking are as follows: 1. Tensioner pulley wear: The tensioner pulley's function is to tighten the engine belt, preventing the generator and power steering pump from slipping. Due to prolonged pressure and high-speed rotation, the bearings inside the tensioner pulley are prone to wear, resulting in noise and resonance. If the buzzing and resonance are confirmed to be caused by the tensioner pulley, it is also necessary to check the engine mounts, as their role is to reduce vibrations and noise generated by the engine. 2. Exhaust pipe deformation: In most front-engine models, the exhaust pipe extends from the undercarriage to the rear of the vehicle. Driving on rough roads or impacts to the chassis can easily cause the exhaust pipe to dent or deform. A deformed exhaust pipe increases exhaust resistance, leading to buzzing and resonance sensations from the exhaust system.
My Prado used to produce a humming resonance noise at around 60 mph. The mechanic found that the driveshaft universal joint was dry due to lack of grease. This vehicle often drives on rough roads, and the cracked driveshaft seal wasn't detected in time, causing all the grease to leak out. After the bearing balls wore out, the gap increased, resulting in a humming noise and steering wheel vibration when rotating. Another common issue is the aging of the right engine mount rubber. Once the rubber cracks, the damping fails, and you can feel seat vibrations even at idle. If new tires are installed without dynamic balancing, wheel hopping at high speeds can also cause humming noises. It's recommended to focus on inspecting the drivetrain and suspension components, as problems in these areas are most likely to cause resonance.
The buzzing resonance is mostly caused by unbalanced rotating components. For example, a bent or deformed driveshaft, or excessive wear and gap in the universal joint can generate high-frequency vibrations during rotation. Loose exhaust systems are also common; if the exhaust hanger breaks, the exhaust pipe may hit the subframe, producing a metallic resonance sound during acceleration. If the wheel hub bearing is damaged, the noise becomes particularly noticeable when the speed exceeds 40 mph, and it may be accompanied by uneven tire wear. Additionally, if the screws of an aftermarket underbody protection plate are not tightened properly, high-speed airflow impact can cause resonance. It is recommended to first identify the source of the noise by listening to its location, then inspect the corresponding area for loose or deformed components.
Last time I was driving my Prado on a long trip, I suddenly felt a buzzing vibration under my feet. When I took it back to the shop and had it lifted for inspection, we found that the transmission mount rubber bush had cracked. When these rubber components age and lose their cushioning effect, engine vibrations are directly transmitted to the chassis. A leaking transfer case oil seal can also cause similar issues, as lack of lubrication in the gears leads to abnormal noises and resonance. Those who modify their wheels need to be especially careful—incorrect ET values can cause abnormal stress on the suspension, making the entire cabin shake while driving. For such problems, it's best to use a stethoscope to pinpoint the source rather than randomly replacing parts and wasting money.
