Hi everyone,

I'm new to the forums and have a 2006 Volvo S40, automatic. Recently, I've noticed a low pitch, harmonic/resonant sound coming from what seems to be the front of the car. The sound increases in intensity directly with vehicle speed. It does not appear to be related to the engine at all...revving in neutral does not produce the sound. There is a slight vibration associated with the sound as it is such a deep sound My thoughts on what may be causing it are:

Severely out of balance wheel...perhaps from a pothole or something?
Warped rotor....although the car brakes fine, no pulsating or anything.
Worn tire...although it is odd that this sound would creep up so quickly in the last few weeks if it were due to this.

I was considering taking it to have the wheels balanced/rotated just to rule that out as it's fairly cheap. Any thoughts as to what might be causing this? Thanks for all the help

 

Did you recently have the tires rotated? If you go too long between tire rotations the tires on the rear will cup as they do not have as much weight on them as the front tires do. This is caused by the rear end bouncing up and down as you hit bumps in the road. The noise will be sort of a WHUMP! WHUMP! WHUMP! that will increase in volume as you go faster and then reduce and finally go away when you get to a slow enough speed. Unless the tires are severly cupped the sound should diminish as the tires start to wear evenly again.

This is a very good reason why you should rotate your tires per the recommended intervals.

I don't think it is a warped rotor because it would most likely affect your braking and you said it is braking fine.

Out of balance wheel would be felt through the steering wheel as well as possibly being heard.

 

To eliminate the noise you may need to replace a front wheel hub with bearing. Jack up the car and spin one of your front wheels to see if you hear any noise, then try the other side. For vibrations it may be a drive shaft axle depending on the milage of the car, I had to do it at 90k miles. search for it on this forum.

 

Chances are you have a bad wheel bearing or bearings in the front. I just had mine replaced (2007 T5 AWD) at 40,000 mi. In all honesty, I'm not too happy with the durability of the vehicle.

John