[2001 V70 2.4T] Oscillating humming noise when driving

Post by **prwood** » 19 Jul 2019, 08:41

Whenever I'm driving, I hear an oscillating humming noise that varies in frequency based on wheel speed, and varies in amplitude based on force on the wheels. For example, at highway speeds going straight, the noise is higher frequency but low amplitude; but if we were to go over a bump, as the chassis was pressing down on the springs, the amplitude would increase. Driving at city speeds, the frequency is lower, and the amplitude seems to be higher, which I'm not sure makes sense unless the car is getting more lift at higher speeds. Since the sound resonates through the car, I am unable to tell exactly where it's coming from, but it definitely doesn't seem to be originating in the front left (in front of the driver). The noise does not change when brakes are applied (other than the same lowering in frequency that occurs when the vehicle slows down due to releasing the accelerator), and the brakes are functioning correctly and not making any unusual noises when applied.

I have checked cold tire pressure, and all tires are around 38 PSI which is where I typically keep it. I haven't lifted the car to fully inspect the tires, but from what I have seen, I don't notice any defects or indication that they are wearing badly.

The noise isn't loud enough to be disruptive to passengers, and drivability and fuel economy are normal, but it is noticeable enough to concern me.

I am wondering if this could be an issue with wheel hub bearings on one or more wheels, or if there are other possibilities? I'd appreciate any suggestions on how to further diagnose this. Thanks!

DrDan · Post by **DrDan** » 19 Jul 2019, 14:37

Does it change when cornering? That would point to a wheel bearing starting to fail. If that's the case, it'll get worse until the noise is very pronounced when cornering and much less going straight.
As for the tires, to remove any doubt, you could change wheels if you have a second set.

Post by **abscate** » 20 Jul 2019, 05:18

+1 to DrDan on the wheel bearing prognosis, and the manner inwhich to check

I’ve found 35-40 mph is the magic speed where a sharp swerve will tell you a front wheel bearing is going. Rears are less effectively diagnosed this way but also rarely fail.

Whir whir whir whir ( swerve) WHIR WHIRWHIR WHIR)

Peter..I drove my badbearing 10-15k miles. They are really robust and overbuilt on these cars, so don’t sweat jumping on the replacement right away. I have some spare wheel seals that I’ll send since I ended up with extras, these were are a TSB that’s help keep junk out of the bearings.

Warning , I did have one bearing I needed a 16 ton press to get out. Also, I torched a cV joint once being stupid. Don’t be stupid

Louder on swerve right means left bearing, louder in left swerve means right bearing.

Georgeandkira · Post by **Georgeandkira** » 20 Jul 2019, 05:40

How many miles are on your '01?

My RF bearing went bad @~175K.

XC70Rider · Post by **XC70Rider** » 21 Jul 2019, 08:37

abscate wrote: ↑20 Jul 2019, 05:18 I have some spare wheel seals that I’ll send since I ended up with extras, these were are a TSB that’s help keep junk out of the bearings.

Hi Steve,

Where did you purchase the seals for the front wheel bearings? Searching online stores I can only find seals for the rear bearings. The seal fell off the drivers side when I rebuilt my front axles last month.

Thanks,

John

Post by **abscate** » 21 Jul 2019, 11:11

The seals aren’t integral to the bearings but go on the hub to keep water out of the bearing’
Stand by for part number

It’s in this hub kit fcp sells too

https://www.fcpeuro.com/products/volvo- ... 80#reviews

XC70Rider · Post by **XC70Rider** » 21 Jul 2019, 13:15

My bearings are fine so I do not want to purchase a whole new hub assembly. The seal is all I need to keep the bearings from getting damaged within a few thousand more miles.

Found it and ordered them after searching numerous different sites PN 30647015

https://www.fcpeuro.com/products/volvo- ... g-30647015

Post by **prwood** » 22 Jul 2019, 07:27

The noise seems to increase when I turn to the right, so I guess that would point to the right front bearing?

The car has 254,000 miles on it at present. I have owned it since 189,000 miles, and I know that nothing in the wheel hub assemblies has been serviced during that time.

My thought is to replace the entire wheel hub assembly. It seems like this would be easier than attempting to replace just the bearing. Is this the type of thing you're supposed to replace in pairs? This OE kit from FCP costs $164: https://www.fcpeuro.com/products/volvo- ... it-fag-kit

Post by **abscate** » 22 Jul 2019, 16:28

That’s the right one. You replace it as a unit, correct, the bearing does not come out separately.

If it’s noisy on RIGHT turn, it s the LEFT bearing that’s bad.

Post by **prwood** » 22 Jul 2019, 19:07

abscate wrote: ↑22 Jul 2019, 16:28 That’s the right one. You replace it as a unit, correct, the bearing does not come out separately.

If it’s noisy on RIGHT turn, it s the LEFT bearing that’s bad.

Should I replace both the left and right hubs, or just the side that seems to be worse? Just wondering if it's one of those things that should be done symmetrically.