Drain Pump Noise in a Bosch Evolution Dishwasher

Mineral Deposits

• Since dishwasher detergent manufacturers changed their formulas to remove phosphates, hard water buildup (mineral deposits) are a common problem in dishwasher maintenance. Mineral deposits can build up on the pump impeller. If the impeller is not as balanced and as light as it was when new, the impeller may vibrate and cause noise. Use citric acid or CLR to remove deposits.

Filters

• Check the filters, looking for food debris or a chip of broken glass that could be blocking the flow of water when the dishwasher fills or drains. Remove the filters, wash with soapy water and a soft toothbrush, rinse and replace.

Air Gap

• Depending on state or city plumbing codes, your dishwasher may have a air gap to prevent back-flowing discharge from entering the washing machines. If your dishwasher plumbing includes an air gap, check the filter. If it is clogged with mineral deposits or dried food residue, the dishwasher cannot drain properly.

Safety First

• Warning! To avoid personal injury or death, always disconnect the dishwasher from its power source before attempting troubleshooting or repairs. Unplug the appliance from the wall or shut off the electrical power at the fuse box or circuit breaker.