I have a 2007 Chrysler Sebring Touring (V6) with almost 80,000 miles and diligent about repairs / oil changes. As of late, a loud revving sound comes from the engine under all conditions. It’s as though the normal revving you would hear when accelerating or decelerating has been amplified significantly. No check engine light, no shaking or vibration within the car, but under the hood there is some vibration and the noise seems loudest near the belt-side.
Could it be that the alternator or another turning part is beginning to fail and is putting a strain on everything else it’s connected to? Doesn’t matter if it’s starting up, short-distance, long-distance, city or highway, A/C on or off. It’s not getting any louder or softer over time. Full oil - I’m really not sure what’s wrong.
The first thing to do is to determine if the engine is revving at higher RPMs than it used to. I am assuming that this car has a tachometer. If the engine is making this noise when you are accelerating, and if the tachometer also shows higher revs than normal, that would point to a slipping transmission.
If the engine’s RPMs are no higher than they used to be, and/or the noise is also heard while the car is stationary, there are numerous possiblities, including (but not limited to) the following:
Dry bearings in belt pulleys and/and or tensioners
A bad motor mount or two
A cracked exhaust manifold
Alternator bearings that are going dry
A/C clutch that is about to self-destruct
Without being able to hear the noise, it is very difficult for any of us to accurately diagnose the problem, but if you can record the noise and attach a sound file or a video, that would help us to help you.