Hey all!

I have a 2006 Volvo C70. Love this car but it's providing me with a frustrating situation. It has a noise when I accelerate from 0-30. It is hard to describe the noise. It's not a clunk, whine, bang or rattle. It almost sounds like electronic grinding. I have already replaced the axle shafts, spindles w/ bearings, brake hardware, lower control arms, tie rods and strut assemblies to no avail. I am an auto tech myself but this one ill uses me. Any help would be appreciated.

 

have you tried having somebody drive by you while accellerating or listen with the window open? short of something internal to the transmission, I'd wonder if it may be coming from the rear wheels.

 

Yes. Can't really hear much outside the car. I also checked the motor mounts and they look good as well.

 

It's definitely the front.

 

Mike, the noise in my own 2006 xc-70 Wagon is very similar to identical to what you describe. The load hum in my vehicle does continue to higher speeds 50-60 mph. Were you able to determine the source and/or problem with the noise in your own vehicle ?

 

So the loud hum that appears to be directly related to INCREASE IN RPMs and not speed. This is likely to be the alternator which will probably need to be replaced. Fortunately my mechanic & I identified the other noise that was more of Grinding and related to steering wheel position as a worn wheel bearing and that has been corrected by replacing the bearing.

Any thoughts on confirming that whirring hum noise associated with RPMs it is the Alternator ?

 

whirring noises that change pitch with engine speed can be any of the accessories ie alternator, power steering pump, AC compressor (clutch) or serpentine belt idler pulleys. you'd probably need to remove the serpentine belt and feel around for any odd feel for the various components. I'd probably be inclined to replace the belt/tensioner/idlers if you are unsure. I forgot to ask, does the noise change as the AC kicks on or off? Does it change if somebody puts an electric load on (ie turn on the blower full/rear defrost/high beams)? when you nudge the steering to load up the power steering?