Low, pulsing, rhythmic humming noise at highway speeds.

JackieChang

Car is 1 month old. 2000km miles on the clock. Exact model is Dacia Sandero.

When i am on the highway and get to around 110 kph a low frequency rhythmic humming / droning activates. Frequency is roughly every 1 second. Sounds like woooom wooom woooom woooom woooom. Say that every 0.7 seconds in your lowest voice possible and that's what it's like. (sorry that spelling the best i could do).

Doesn't sound like anything is scraping or grinding so proabably not bearings. It just suddenly appears at 110kph ish.

I did try to steer to the left and the right to see if the hum went away but it didn't make a difference. However I can't do much turning at those speeds.

Seems to be coming from the front passenger area.

It's kind of driving me a bit insane. My girlfriend can't really hear it. Probably because she could be driving her own car with no bloody tyres and she wouldn't notice but it makes me think the mechanic may have trouble hearing it too. So i would like to be certain of what this is before i roll it into the shop under warranty.

Strangely it reminds me of my movie projector at home. When the fan is spinning, on top of the high rpm fan rotating noise, there is also a rhythmic, low humming that resonates with the wooden table every second or so. Maybe a related physical phenomenon?

tl;dr: car make funny low noise woooom wooom woooom woooom woooom every 1 second.

Timfy

Is it on every road? I notice a similar noise in a Renault Captur when travelling at around 110 kph on new sections of road. I had it explained to me that it is due to very slight, visually imperceptible undulations in the tarmac caused by the Blaw Knox* tarmac laying machines. These undulations are at regular intervals due to the way the rollers operate and can cause a thrumming noise, sometimes even a slight vibration.

*Other road making plant may also be available!

Hermy

It wouldn't just be the low wear indicators on the tyres by any chance?

Miscreant

https://www.boards.ie/discussion/comment/119568111#Comment_119568111

After 1 month and 2k miles on a new car, I would hope not.

There is a particular stretch of motorway heading from Galway to Dublin where I experience the same symptoms at about 100Kph. It disappears when the surface of the road changes. If your Dacia is only having these symptoms on a certain part of the motorway then I wouldn't worry about it. If it is everywhere you drive at 110Kph then I would suggest you get your wheel balance checked or perhaps you have a loose track rod end or defective bushing in the front steering/suspension. A good garage should be able to check that for you or, as your car is under warranty, you could go back to Dacia and have then check the car over.

10-10-20

It may be a wheel or tyre causing harmonic vibrations within the chassis. You could have a fitter swap the wheels from front to back and see if it's the same. Often those issues are just down to a very slight imbalance in a wheel/tyre and won't happen on another axle.

Hermy

https://www.boards.ie/discussion/comment/119568411#Comment_119568411

"Car is 1 month old. 2000km miles on the clock."

Yes, I see that now. Probably not the tyres so! 😀

JamBur

Plastic shield under the car sightly flapping when you hit higher speeds?

JackieChang

https://www.boards.ie/discussion/comment/119568436#Comment_119568436

Would a harmonic vibration pause robotically every one second?

JackieChang

For the others, I'm not sure if it happens on every road surface. I think it does, but I'll double check that.

User1998

Sounds like a wheel bearing to me

Wishbone Ash

Does it go away again if you go above 110? Try 120/130 to see.

Atlantic Dawn

Could it be from the passenger door window, a poor seal perhaps on window or door that is catching the air? Have you tried putting that window down when the noise occurs to see if it goes away?

JackieChang

https://www.boards.ie/discussion/comment/119569397#Comment_119569397

Nope. It just begins at 110. Max I've gone is 130, haven't tested above that.

JackieChang

https://www.boards.ie/discussion/comment/119569482#Comment_119569482

I've had leaky windows before, they don't make a robotic, repetitive sound every 1 second. A drafty window at 100kph is constant noise.

JackieChang

https://www.boards.ie/discussion/comment/119568083#Comment_119568083

Just went for a spin in the missuses fiesta on the same stretch of road and didn't notice anything.

Curious_Case

https://www.boards.ie/discussion/comment/119568436#Comment_119568436

Yes, I reckon tyre & wheel balancing conditions are just right to cause a panel under passenger's feet to vibrate.

The back seat behind my driver's seat used to vibrate sometimes, so much so that it looked out of focus in the rear view mirror. It made the low humming sound you describe.

JackieChang

https://www.boards.ie/discussion/comment/119571471#Comment_119571471

Did the humming sound have a pulse and quieten down every 0.7 seconds or so?

Curious_Case

https://www.boards.ie/discussion/comment/119571488#Comment_119571488

I think it was fairly similar, an audible resonant frequency with a slight beat (the term "beat" refers to guitar tuning, the slower the beat, the closer 2 strings are in pitch). Every panel is different though, shape, size, thickness, rigidity, so no 2 conditions will ever match.

Iodine1

Had similiar with a new car some years back, got worse as the tyres wore. Everyone said it sounded like a wheel bearing but bearings were fine. Eventually changed the tyres on the back, new but different brand from the originals, and the noise disappeared completely.

10-10-20

https://www.boards.ie/discussion/comment/119569113#Comment_119569113

If it's harmonic resonance, then yes it could.

Harmonic resonance is when multiple vibration waves at different frequencies meet, and depending on the scenario they can have a synchronous effect. Just don't rule it out.

gameoverdude

Watch stranger things. Not saying you're in trouble...but...

But harmonic resonance sounds right. Why? I'm not sure.

Could this cause damage. Potentially.