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Why is my dishwasher making noise? Causes and fixes

By: Reliable Parts • July 2026

A dishwasher that makes unusual noise is most often caused by hard debris in the drain pump or chopper area, a spray arm striking dishes, or a worn circulation pump motor bearing. Grinding or rattling usually means debris, rhythmic clicking or knocking means spray-arm contact, and a droning or squealing that grows over months means the motor bearing. Identify your dishwasher’s model number to order the correct replacement parts.

Need step-by-step instructions for your specific brand and model? Visit our DIY Repair Guide and filter by appliance and brand.

Safety information

Disconnect power at the breaker before reaching into the sump - most dishwashers are hardwired, and the chopper blade and heating element sit exactly where hands go. Wear cut-resistant gloves when clearing the sump; broken glass in the pump area is the most common cause of these noises and of injuries repairing them.

Most common causes

  1. Hard debris in the pump or chopper — glass shards, fruit pits, and bone fragments rattle and grind in the sump; the most common source of alarming new noises.
  2. Spray arm striking dishes — tall items or protruding handles block the arm’s rotation, producing a rhythmic click or knock.
  3. Worn circulation pump bearing — a drone or squeal during the wash portion that has grown steadily louder.
  4. Failing drain pump — a buzz or grind concentrated in the drain portion of the cycle.
  5. Water hammer at the inlet valve — a bang or thud in the pipes when the fill valve snaps shut; a plumbing and valve issue rather than a pump issue.
  6. Worn or loose sump check valve — a repetitive knocking during drain on some models.

Step-by-step diagnosis

  1. Identify when the noise occurs. Noise during wash points to the circulation pump, spray arms, or debris in the sump; noise during drain points to the drain pump or check valve; a bang at the start or end of fill points to water hammer at the inlet valve.
  2. Run the dishwasher empty. If the noise disappears, the loading was the problem - a spray arm was hitting dishes or items were vibrating against the rack. Spin each spray arm by hand to confirm full, free rotation before every load.
  3. Disconnect power, remove the filter assembly and lower spray arm, and inspect the sump. Remove glass, pits, and bone fragments with pliers - check the chopper or grinder area carefully, as a single glass shard produces a dramatic grinding noise.
  4. Inspect the drain pump impeller through the sump opening where accessible. Clear debris and confirm the impeller turns without grinding. A drain pump that still grinds when clear has failed and should be replaced.
  5. Evaluate the circulation pump motor. A drone, rumble, or squeal during wash that persists with a clean sump and empty tub indicates the motor bearing. Replace the circulation pump or motor assembly per the model’s design.
  6. Address water hammer if the noise is a pipe bang at fill start or stop. Secure loose supply pipes, and install a water-hammer arrestor on the dishwasher supply line. A worn inlet valve that closes abruptly can also be replaced to soften the shutoff.
  7. Check the sump check valve on models with a knocking drain. A worn flapper chatters as water pulses past it; the valve is inexpensive and replaces from inside the sump.

Replacement parts to consider

Common parts for a noisy dishwasher: drain pump, circulation pump/motor assembly, spray arm, filter assembly, check valve, water inlet valve, water-hammer arrestor. Enter your dishwasher’s model number on reliableparts.com for the exact parts for your specific model.

Related FAQs

Why does my dishwasher make a grinding noise?

Grinding almost always means hard debris - broken glass, a fruit pit, or a bone fragment - caught in the drain pump or chopper area of the sump. Disconnect power, remove the filter and lower spray arm, and clear the sump. Grinding that persists with a clean sump means the pump itself has failed.

Why does my dishwasher click or knock rhythmically during the cycle?

A steady click or knock in time with the wash action is usually a spray arm striking a tall utensil, pot handle, or misloaded dish. Stop the cycle, spin both arms by hand, and rearrange anything in their path. If the knock continues when empty, check the arm for cracks and the check valve during drain.

Is it normal for a dishwasher to make noise?

A steady wash whoosh, periodic drain hum, fill-water sound, and occasional detergent-door click are all normal. The sounds worth diagnosing are new ones: grinding, squealing, rhythmic knocking, or a drone that is clearly louder than the machine’s baseline. Compare against how it sounded when new.

How much does it cost to replace a dishwasher pump?

A drain pump typically costs $30-80 and is a manageable DIY repair on most models - accessible from the sump or by tipping the unit. A circulation pump or wash motor assembly runs $80-200 in parts, with professional replacement of either generally between $150 and $400.

Why do my pipes bang when the dishwasher fills?

That bang is water hammer - the inlet valve snaps shut and the moving water column slams to a stop in the supply pipe. Secure any loose pipe runs and add a water-hammer arrestor to the dishwasher’s supply line. An aging inlet valve that closes harshly is worth replacing at the same time.