Symptoms
- Whine pitch tracks road speed, not just RPM
- Noise present in some gears but not others
- Whine gets louder under load (acceleration or hills)
- Vibration may accompany the noise at certain speeds
Likely causes
- CommonWorn transmission bearingsBearings supporting rotating shafts wear over time and whine as clearances increase.
- CommonLow or degraded fluidInsufficient lubrication increases friction noise throughout the gear train.
- PossibleWorn gear teethWear on specific gears can create a whine only in the gear ratios that use them.
- PossibleDifferential noise (often mistaken for transmission)The differential can produce similar speed-related whine and is worth ruling out separately.
- PossibleWheel bearing noise (often mistaken for transmission)A bad wheel bearing changes pitch with speed and can sound similar from inside the car.
What to do
- Note whether the whine changes with turning (pointing to a wheel bearing) or is present regardless of turns.
- Check the transmission fluid level and top off if low.
- Note which gears the whine appears in, since gear-specific noise points to that gear pair.
- Try coasting in neutral at the affected speed briefly (where safe) to see if the noise continues, which would point away from the transmission gears themselves.
- Avoid ignoring a worsening whine, since bearing or gear wear tends to progress and can lead to sudden failure.
- Have a shop road-test the vehicle and use a lift to help isolate transmission, differential, or wheel bearing noise.
- Get the confirmed source repaired rather than continuing to drive on worn bearings or gears.
Tools and parts
- None for initial checks
Transmission fluid (correct type for vehicle)Search: “transmission fluid type for [make model year]”
When to call a pro
See a mechanic for a proper diagnosis, since transmission, differential, and wheel bearing noises can sound alike from the driver's seat but need very different repairs.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.