2008 Cobalt.

Has become noisy, like a revved up sound (errrrrrr, errrrrrrr) maybe like the car grew some ***** but thats not the case.

It only occurs when you acclerate past 15-20 mph. Coasting at like 35-45 its loud and decreases in resonance as the car slows and comes to a stop. Comes from the front but cant tell if its from engine or vibration.

It does NOT occur when in neutral/idle or park when you rev it up (RPM's never go past 4000 when I do that, kinda stuck there?). I first thought muffler/exhaust but I figure that would be loud when just idle as well. If I am just rolling in idle drive I dont hear anything that would indicate the tires rotating... it only occurs when getting up 20 mph and above.

Anyone want to take a stab at a guess?

 

Tires or wheel bearings? Always hard to diag a noise you can't hear in person...

 

I understand its impossible without hearing it. But give it a shot.

AS far as wheel barings, I thought of that as well. Is that a major fix? $$$$

 

Wheel bearings aren't hard at all to replace. I would go with GM ones...shop around online, gmpartsdirect.com, crateenginedepot.com, even amazon or eBay.

 

Easy way to check wheel bearings: Jack up the car (lift makes it faster) and spin the wheel by hand, feel the spring or directly on the knuckle. If you feel any rumbling/roughness, the bearings are toast. Pretty common for them to fail and no it's not a big deal to replace at all. My record is about 10 min start to finish for a front wheel hub but I had my tools pretty much laid out ahead of time.

 

Ive been reading online about the bearings/hub and it sounds kinda like what other are describing.I will take a look tommorow afternoon.

....if its just the bearings, do you have an idea about a ballpark figure on replacement by a mechanic shop?

 

Labor is under an hour for the fronts, and the part should be under $100 retail. I'd say $200 for one would be kind of a high estimate.

 

It was a wheel bearing that was shot. All fixed, noise is gone...

Good call dsmnutz!

 

Have been having this same problem, I assumed it was some kind of bearing or the like because of lack of noise at idle. If I do not immediately fix, could it cause more damage to anything else?