Hi everybody!

I'm a newbie to this forum and to Volvo ownership. I searched the forums and didn't find my problem addressed, so I hope someone can help me.

I bought a '01 XC70 with 103k miles sight-unseen. Really good price ($7500), but boy, I didn't know what I was getting into. I won't get into those issues yet, my main concern right now is a humming, whirring, droning sound coming from the rear end. It starts at about 20mph as a deep growl, get's higher pitched as I speed up, and settles into a nice drone by about 55mph. Changing lanes quickly DOES affect the pitch somewhat, but it doesn't make it go away. I've had the car a month and it seems to be getting louder.

I've definitely ruled-out exhaust and rear tires. I'm thinking rear differential or a wheel bearing. Any thoughts? What about costs if it is one of those?

Any help is greatly appreciated. I'm not letting this get me down, because even with it's flaws I love this car!

Thanks!

 

If you are SURE it is not a tire then I would strongly suspect a rear wheel bearing. How did you eliminate the tires as a cause?

 

Took it to my the tire shop. There's absolutely no abnormal wear on the rear tires and it's been doing this since I've had the car which is about 4000 miles. I would have addressed this sooner, but I also had a badly corroded exhaust system, so I thought the noise was coming from the muffler. It wasn't until the muffler was fixed that I could distinguish the sound was tire or wheel related. So, when I took it in for an alignment, the mechanic at the tire shop looked at the tires and drove the car with me and said it wasn't the tires. Had to be the differential or a bearing. Based on the change in pitch when turning, he said he though it was the bearings.

My general mechanic is on vacation so he hasn't looked at it yet. He's a good friend of mine and we barter on labor so he takes really good care of me and I trust him like family. I will always go to him first, before going to the dealer, unless it's something he's not comfortable with. He's never changed the bearings on a Volvo, so he doesn't know if he can do it or not. Are there any special tools needed, or is the Volvo unique compared to other bearings?

He's already done the brakes, fuel filter, tune up and fixed a few odds and ends like a broken motor mount. But I had to bring it to the dealer to fix the door locks. Turns out the right rear door lock was bad, causing none of them to work. Also, took it to the dealer for an oil pressure warning light. The oil feeder tube was clogged, not getting oil to the top of the motor. He probably could have done that job, but I'm not sure I was comfortable, being that he hasn't worked on a lot of volvos.

BTW, is there any way I can diagnose the bearings since my mechanic is out of town?

 

From your description of the noise it definitaly sounds like a wheel bearing. I have seen a lot of these go bad. The easist way is to put the car on a rack and drive it and listen for the noise from each wheel and check for play in the wheel as well.

 

Within weeks ofbuying my used 2003 xc70 (95,000km) I had a droning sound that would change pitch at different speeds. My mechanic and I went for a test drive since he didn't think it was the brand new tires. What he told me to do (which now makes perfect sense) was to swerve from side to side and see if the droning noise changed. When I swerved to the right, it took the weight off of the right rear bearing. Instant silence! When I swerved to the left, and put more weight on the right rear bearing, the noise became more intense. Luckily for me, my 90 day warranty covered the fix which I'm told was $6-700.

 

Just thought I'd give an update in case anyone reads this thread in the future wth the same problem. Turns out it was the rear bearings and the "swerve test" is exactly what my mechanic did to diagnosis it too. He did both sides and the parts were about $120 per side (!). He had to beat like the devil to get one side off, the other came out easy. No special tools other than the bearing puller which he had to modify to fit the lugs on the Volvo. But it worked and I guess it could have been worse.