Have you popped the hood and looked? Sometimes you can see a belt or pulley rubbing on a mispositioned plastic splash shield. The engine shifts position a little when it's in gear, (automatic transmission). On some cars you can hear an emissions system solenoid cycling on and off about twice per second. You will be able to feel that too. There isn't much you can do about that other than to be sure it's tight in its mounting bracket. People have been known to wrap them in a piece of foam.
If nothing else works, visit the dealership and point it out to one of the mechanics. If they can't find it, there is a tool called the "Chassis Ear" that consists of six microphones and a set of headphones. You can switch between them and listen while driving, then the microphones can be moved around to zero in on the source of the noise. One note though; a lot of professionals have never heard of this tool or seen it. Every Chrysler dealership has one but it doesn't see much use except by the steering and suspension specialists. It is also available from the tool truck guys like Mac, Matco, Cornwell, and Snapon.
Sorry I can't be more specific without hearing it.
Sunday, November 28th, 2010 AT 12:20 AM