You could bring a long dowel rod on the ride with you and get it to start making the noise and put the dowel
up to your ear and place the other end on various components until you find where it is the loudest.
You could probably even hear the noise using this method with a screwdriver while it is on the stand since
it will amplify the noises. Auto mechanics have stethoscopes made just for this but they have a long metal
rod connected to it for diagnosing motor noises, But a long screwdriver or wooden dowel rod works just as
well!!