What would make a clothes dryer sound like a rock tumbler? The loud noise comes from the vent and is audible outside, but it is not audible inside. There are no visible obstructions in the vent. What could be causing this noise? How can this problem be fixed?

Try running the dryer with no clothing in it and the door open and on "air fluff" (no heat). You will have to hold the door switch in to do that. You will probably find that there is something, such as a coin, in one of the vanes of the dryer. To tell you how to fix that, we need the name and model number.

Try running the dryer with no clothing in it and the door open and on "air fluff" (no heat). You will have to hold the door switch in to do that. You will probably find that there is something, such as a coin, in one of the vanes of the dryer. To tell you how to fix that, we need the name and model number.

Thank you Jim! That is helpful information. This noisy dryer belongs to my neighbor. I will have to see if I can get that information from him. They have replaced the outside air vent flap, but that was not the problem. I will be very happy if we can figure this out.