Ok I have a 09 XC90 3.2 AWD.It has 145k and well maintained.The last month or so I hear a humming sound at cruising speeds.A bearing of some sort?I jacked my car up to spin the front wheel but you cant spin it,even in neutral.I just dont know where its coming from,seems to be getting worse.Any sugestions on how to find where its coming from and are there common problems with my vehicle at this mileage?

 

I think that you will need more detective work. Have a friend ride in the back and see if they can tell where the sound originates while you drive.

 

Hey smokey1, this is an old post. Did you ever figure out what it was?

 

Don't think Smokey's problem will tell you what's up with your car - only what was going on with theirs. If you have a similar noise at speed you should start doing your own investigating - Does the sound change when driving a sweeping left hand turn vs a sweeping right hand turn (say at 40-50 MPH)? - if so, I'd suspect a wheel bearing on an outside wheel Does the sound change when you lightly apply the brakes? does the sound change when you apply power or lift off the throttle? If so, I'd suspect an axle. Not sure if you can engage AWD on command, if so repeat the steps above. engaging AWD will put stress on the rear axles and drive shaft bearings. Have you tried a front/rear tire rotation to see if the sound changes in the cabin?

 

Thanks for the list of potential things that could cause humming sounds. I don't have the car but am going to look at one for sale and the ad reports humming over 40mph. So, I both want to get a feel for what things could be wrong (and ~price to fix) and how to determine semi-quickly.

 

The humming in my car also turned out to be wheel bearings.

 

in terms of costs, brakes and wheel bearings are reasonable cost to replace. When it comes to axles/CV joints, you'd want to be careful going with after market on a car you plan on keeping. Genuine volvo axles run in the 450 to 700 range but are guaranteed to fit and last...