Why Is My Dishwasher Making a Loud Noise?

A dishwasher making loud noise during a cycle — grinding, banging, rattling, or a high-pitched squealing — is alarming, but the cause is usually identifiable and often fixable without professional help. Dishwashers aren’t quiet appliances, but they have a normal operating sound profile. Noise that’s new, sudden, or dramatically louder than usual always has a specific cause.

This guide covers every type of dishwasher noise, what’s causing it, and what to do about each — starting with the simplest checks and working toward mechanical issues.

Normal vs. Abnormal Dishwasher Sounds

Before diagnosing, it helps to know what’s normal. A running dishwasher typically produces: a soft hum from the pump motor, whooshing or sloshing as water sprays through the arms, clicking as spray arms rotate, and a louder sound during the drain cycle as the pump pushes water out. These are all expected.

What’s abnormal: grinding, scraping, banging, rattling, buzzing louder than usual, or a persistent high-pitched squeal. These point to specific problems.

1. Rattling or Banging — Something Is Loose Inside

The most common cause of rattling during a cycle is loose items in the dishwasher — a utensil that’s fallen through the basket, a small lid that’s shifted, or a lightweight plastic item that’s tumbled onto the lower rack during the fill cycle and is now being buffeted by water jets.

• If the rattle started mid-cycle, stop the machine and check for loose items. A small piece of cutlery or a bottle cap under the lower rack is the most common culprit.
• Also check that the lower spray arm is secure — it should snap on firmly. A loose spray arm rattles and bangs against the bottom rack.
• Inspect the spray arm itself — sometimes a piece of debris lodged in a jet causes the arm to wobble unevenly as it rotates.

2. Grinding Noise — Filter or Pump Debris

A grinding sound during the wash or drain cycle almost always means debris has gotten past the filter and into the pump. Small glass fragments, pieces of broken ceramic, cherry pits, fruit seeds, or small bone fragments can all make it into the pump and cause a grinding or crunching sound as the impeller blades hit them.

• Stop the machine immediately when you hear grinding — debris in the pump can damage the impeller blades.
• Remove and clean the filter (the cylindrical filter and flat mesh at the bottom of the tub).
• After cleaning the filter, run an empty cycle and listen — if the grinding continues, debris is already in the pump and will need to be cleared by a technician.
• Always check pockets and scrape plates before loading — this is the most effective prevention.

A filter that’s never been cleaned is also a risk factor here — our dishwasher not draining troubleshooting guide covers filter maintenance in detail, since a clogged filter contributes to both draining problems and pump stress.

3. Loud Humming or Buzzing — Water Inlet Valve

A buzzing sound during the fill phase of the cycle (when water is flowing in) often indicates the water inlet valve is partially blocked or starting to fail. The valve buzzes when it vibrates due to restricted flow or a weakening solenoid.

• If the buzzing happens specifically when the machine is filling (the first few minutes of the cycle), the inlet valve is the likely cause.
• Check the water supply hose for kinks that restrict flow.
• A humming or buzzing inlet valve that’s worsening over time typically needs replacement before it fails completely.

4. Squealing or Whining — Pump or Motor Bearing

A high-pitched squeal or whine — particularly during the main wash cycle when the circulation pump is running at full speed — usually indicates a worn bearing in the wash pump motor or circulation pump. Bearings wear over time, particularly in hard water areas where mineral deposits accelerate wear.

• This sound is distinct from grinding — it’s a continuous tone rather than intermittent crunch sounds.
• It often gets louder as the cycle progresses and the bearing heats up.
• Pump and motor replacement is a mid-level repair — manageable for experienced DIYers but typically best done by a technician on higher-end machines.

5. Banging or Knocking — Spray Arm Hitting Dishes

A rhythmic banging or knocking that coincides with spray arm rotation means a spray arm is hitting dishes during the cycle. This happens when items are loaded too tall in the lower rack, blocking the upper spray arm, or when items stick through the lower rack preventing the lower arm from rotating freely.

• Check that no items extend above the top of the lower rack enough to block the upper spray arm.
• Make sure tall items like cutting boards aren’t positioned where they’ll be hit during arm rotation.
• After correcting the load, run a short cycle and listen to confirm the banging stops.

6. Noise During the Drain Cycle

Some drain noise is normal — the drain pump is louder than the wash pump. But a particularly harsh draining sound, or one accompanied by incomplete draining, suggests a restricted drain path. Check the filter, the drain hose for kinks, and the drain connection under the sink for blockages. Our dishwasher troubleshooting guide covers the drain system comprehensively.

Using Error Codes to Help Diagnose

Many modern dishwashers display error codes when they detect internal faults — including pump and motor issues. If your dishwasher has a display panel and is showing a code alongside the noise, our appliance error code cheat sheet can help you decode it and narrow down the cause.

When to Call a Professional

Loose items and loading errors are DIY fixes. Filter cleaning is a DIY task. But grinding caused by debris already in the pump, a failing pump motor, or a worn bearing — these require hands-on access to the pump assembly that’s best handled by a technician to avoid further damage.

North Vancouver Appliances handles dishwasher repairs and noise diagnosis across North Vancouver and the North Shore. Visit our dishwasher repair page to book a visit.