There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.

Answered by caradiodoc (expert)
17,654 answers provided

Thats pretty neat. If you had to guess what could be making the noise?

Response from rmoore09
75 questions asked

Exhaust pipe, broken leaf spring, axle control arm bushing, loose bowling ball, loose spare tire. I CAN say with 100 percent accuracy that guesses are always wrong and will send you on a wold goose chase.

Answered by caradiodoc (expert)
17,654 answers provided