This is on a Maytag MDBD880AWW dishwasher (will be on many other similar designed Maytag dishwashers as well)
It was making a grinding noise only when draining.
I thought it was the drain impeller except that it was draining, but making a huge grinding sound only when it was draining.
It was a broken upper discharge housing, which we bought new one.
The broken off disc will float up during the wash cycle and not make a noise, when the dishwasher is draining the broken off disc will drop down and hit the wash impellor making the noise.
click on the picture for a larger view
Thank you kelly for the information and pictures! :-)
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