, this electric dryer started making a loud thumping noise recently that has become progressively worse since it began. Described as a rhythmic double thump sound, I figured it was the usual drum seam rolling across the two support rollers, but once I was able to get a look at the unit, the prognosis became a bit more grim.
All dryers will utilize some form of support for the drum assembly that can range from center bearings, to felt glides, or even in the case of this dryer, a set of rubber rollers. These rollers are mounted to the rear and often times front bulkheads and roll within a recessed portion of the drum. Rollers are a good method of support as they resits wear to the drum surface, reduce friction for the drive system, and allow for quiet operation. The one notable downside to the use of support rollers, is the normal double thump sound made as the drums seam contacts each roller while rotating. The sound will usually start out loud at the beginning of a drying cycle, then becomes quieter as the rubber on the rollers warms up and becomes more ply able. Many people hear this sound as a familiar dryer sound, but when it becomes more pronounced, there may be a problem.
As mentioned, the drums seam is usually the cause of the noise. When drums are produced from a single sheet of metal, the seams come together to be welded making one continuous drum. The seam is then ground smooth in the area of the roller track to help reduce the noise created by the support rollers. Because the noise on this unit was clearly from the seam, I opened the top panel to get my eyes and ears on the situation. With each rotation, the double thump was very noticeable and when I stopped the drum to take a look, I quickly located the source of the noise.
The drum on this dryer has not aged very well as the weld had broken where it secured the two ends of the metal together in the rear roller track. This resulted in the formerly smooth edge becoming a large bump as the weight of clothes forced the metal ends to flex open. Each time this edge contacted a roller, the noise echoed in the cabinet and throughout the rest of the room.
The only good repair for this dryer is to replace the drum assembly which is a rather large expense, but because the customer was happy with the machines performance, plus it matched the washer, she was willing to pay to have it fixed. I installed a new drum along with a set of new support rollers, and now this dryer is as quiet as it has ever been.