Model #GU2500XTPQ6, this tall tub dishwasher began making a noise while washing that became progressively worse over time. Because the unit was still functioning properly, there seemed no immediate reason for a service call, but eventually, the noise of the unit won out, and I was called in for the repair.
Dishwashers use a motor and shaft mounted impeller to recirculate water throughout the tub during a wash cycle and depending on make and model, may also be used during the drain cycle to remove the dirty water. The motor and impeller comprise the pump portion of the unit and will be be mounted vertically or horizontally to a sump located under the tub. Rotating at high RPM's, these pumps can move small amounts of water under fairly high pressures during a typical wash, resulting in clean dishes at the end of the cycle.
Many dishwashers use screens to filter the recirculated water to protect the impeller and motor from damage caused by large food particles or foreign objects that find their way into the dishwasher. Others, like this model, will use a chopper blade (see below) to help break down organic material into small particles for easy removal from the sump during the drain cycle. These screes are often the source for high pitches noises that last for seconds to several minutes as the impeller or chopper work to grind down this material until it is able to pass through the screen and out with the waste water.
Unfortunately, if the noise doesn't fade after a brief period, or continues to get worse, the most likely reason is something stuck that cannot be reduced to pass out of the sump. Or worse (more expensive), something hard that contacted the high speed impeller resulting in permanent damage to the motor shaft. Which, by the way, is what was causing the noise on this unit. Even with the motor removed from the sump assembly, the noise continued so I knew it was time to be replaced.
The sump and pump assembly on the Whirlpool products is very easy to service without the need to pull the dishwasher out from under the counter and is often replaced as a complete pump and motor assembly. But this customer was on a tighter budget and after looking over the rest of the sump, I determined only the washer motor itself needed replacement. Removed the sump, installed a new motor, and now this dishwasher is as quiet as it has ever been.
It is important to remember that routine cleaning of filter screens and chopper assemblies along with proper scrapping of dishes prior to washing can go a long way toward preventing this kind of service call.
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