A whining noise that rises and falls with acceleration usually comes from something that spins with the engine or the wheels: a low or failing transmission pump or torque converter, a worn differential, a power steering pump, an alternator, a belt or idler pulley, or a worn wheel bearing. On supercharged engines, some whine is simply the sound of the supercharger. Matching the noise to engine speed or road speed is the quickest way to find it.
Engine speed or road speed?
- Changes with engine speed, even in park: belt-driven accessories such as the power steering pump, alternator, water pump, idler pulleys or a supercharger.
- Changes with road speed: the differential, wheel bearings or tires.
- Changes with gear or only in gear: the transmission, its pump or the torque converter.
Common causes of whining when accelerating
- Low transmission fluid: the pump draws air and whines, often with slow or slipping shifts. Check the level and look for leaks; see transmission fluid leak.
- Transmission pump or torque converter: a whine that changes with gear or engine load; see bad torque converter symptoms.
- Differential: worn ring and pinion gears whine under acceleration or deceleration; check the gear oil level.
- Power steering pump: louder when turning the wheel, often from low fluid.
- Alternator or idler pulleys: worn bearings whine or chirp with engine speed.
- Wheel bearings: usually a hum or growl that changes when turning.
Whining noise when accelerating at low speed
A whine that is loudest pulling away and fades at cruise points toward the transmission pump, torque converter or a low fluid level, because those parts work hardest under load at low speed. A whine that only appears at highway speed is more often the differential, a wheel bearing or tire noise. Recording the noise on your phone at different speeds helps a technician pin it down.
Supercharger whine
Many superchargers make a characteristic whine as boost rises, and owners often like it. A centrifugal supercharger’s pitch climbs with engine speed. A new grinding or rattling noise is different and should be checked. See what does a supercharger do?
Transmission whining: what to check
- Check the fluid level and condition with the engine warm, as your manual describes; see how to check transmission fluid.
- Note whether the whine changes with gear, speed or engine load.
- Look for leaks at the pan, cooler lines and seals.
- If the fluid is dark and burnt, or the transmission slips, read transmission slipping: signs and causes.
When a transmission is worn beyond repair, find a replacement by code on our transmissions page.
More guides: bad alternator symptoms · serpentine belt and pulleys · transmission noise · car shakes when accelerating · wheel bearing noise · differential noise · power steering pump noise · bad transmission pump symptoms.
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