Imagine you’re driving down the highway one day, completely at ease. There’s no traffic and a nice, empty road stretches out in front of you. You’re well below the speed limit, so you decide to hit the gas a bit and enjoy the smooth sailing. Except, what if it isn’t as smooth as you’d hoped? If you start hearing a rattling sound when accelerating at low speed, it’s a sign that something’s wrong. Today, we’ll look at the different possible causes behind transmission acceleration rattle.
Acceleration rattle can sound like buzzing, humming or grinding. Whatever the case, if this rattling occurs, it’s best to check for these culprits:
The motor mounts insulate engine vibrations from the frame. If one of the motor mounts has had its rubber parts compromised by engine oil so that it gets soft and the metal parts touch as the engine torques during acceleration, you may feel an unusual vibration or hear a rattle.
A vehicle can have multiple heat shields around its body, such as near the catalytic converter, engine bay, and exhaust manifold. If one of these heat shields becomes loose or develops a crack, then it might start vibrating in place when the powertrain reaches its resonant frequency, producing a rattling noise.
Drive belt pulleys and tensioners are only two of these possibly problematic components. If you’re confident in your DIY abilities, you can check some of these components by pinpointing the noise in this area (be careful around belts and don’t wear necklaces or long hair while checking) and then removing the belts and restarting the engine to see if the rattle is still there (not accelerating, but idling and snapping the throttle).
Worn or faulty wheel bearings might cause whining, squeaking, chirping, and rattling noises when your vehicle accelerates. This generally starts as a barely noticeable noise and then gets worse over time. Wheel bearings don’t typically rattle; they tend to roar or rumble and the sound may change when you change lanes due to which bearing is loaded during the lane change.
If your wheels are misaligned or the tires are imbalanced, it can cause both shaking and rattling noises that come and go at certain speeds.
Check your wheels for wobble and to see if the rims are bent. Change your wheels if you notice damage, and have an expert check your vehicle if you notice wheel misalignment.
While you can always investigate these issues yourself, acceleration rattle causes can be hard to pinpoint. Some problems are easy to handle, like faulty bearings or low transmission fluid. Other issues will require expertise and professional tools. If you can’t find the cause of your vehicle’s acceleration rattle, take it to the auto repair shop right away. It’s better to be safe than sorry.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.