Dishwasher Making Loud Noise? Here's What Each Sound Means

Your dishwasher has always made some noise — that's normal. But when a new sound appears, or an existing one gets noticeably louder, it's the machine telling you something specific. The good news: most noises map directly to a component, and once you know what you're hearing, the diagnosis becomes straightforward.

🔍 Quick Reference: Sound → Most Likely Cause

Sound	When It Happens	Most Likely Cause
Loud humming or buzzing	Throughout the cycle	Worn motor or pump
Grinding or crunching	During wash or drain	Debris in the pump, worn bearings
Banging or thumping	Randomly during cycle	Spray arm hitting dishes or rack
Rattling	Throughout the cycle	Loose dishes, worn rack wheels
Squealing or whining	During drain	Drain pump motor failing
Clicking	At cycle start or between phases	Normal relay switching — usually fine
Knocking	During fill	Water hammer in the supply line

😤 1. Grinding or Crunching

This is the sound most people panic about — and for good reason. A grinding noise almost always means something is physically interfering with a moving part.

Most likely causes:

• Debris in the wash pump — a broken piece of glass, a small bone fragment, or a chunk of hard food that made it past the filter and is now caught in the impeller
• Worn bearings — when the motor bearings wear down, the grinding is more consistent and rhythmic, not random
• Damaged pump impeller — the plastic fins inside the pump can crack over time, especially if debris has passed through repeatedly

What to do:

1. Check and clean the filter first — remove any visible debris
2. Inspect the bottom of the tub for broken glass or hard fragments
3. If the grinding persists after the tub is clear, the pump or bearings need closer inspection
4. A consistent metal-on-metal grind points to bearings — that's a component replacement, not a cleaning job

💥 2. Banging or Thumping

Occasional banging during a cycle is almost always one of two things: aspray arm hitting something it shouldn't, or a loose item shifting inside.

Signs it's the spray arm:

• The banging is rhythmic and repeating — matching the arm's rotation speed
• Sound stops if you open the door mid-cycle and reposition a tall item

Signs it's something loose:

• The sound is random, not rhythmic
• A lightweight item like a plastic lid flipped over and is rolling around the tub

What to do:

• Reload the dishwasher — nothing should hang below the rack level or extend above the upper rack into the spray arm's path
• Check that the spray arm itself is properly seated and not physically cracked or warped — a damaged arm can wobble and strike the racks during rotation
• If the arm looks fine but still catches, check the rack for bent tines that are pushing items out of position

Related: If your dishwasher is running quietly but still not getting dishes clean, the problem is usually different — a clogged filter, low water temperature, or a spray arm that's blocked rather than broken. We break down every cause and fix in detail here: Why Is My Dishwasher Leaving Dishes Dirty? Common Causes and Fixes

🌀 3. Loud Humming or Buzzing

Some hum is completely normal — it's the motor and pump doing their job. What's not normal is a hum that's noticeably louder than before, or one that's accompanied by weak cleaning performance.

What the hum tells you:

• Normal, consistent hum — motor running as expected, no action needed
• Louder hum + poor cleaning — pump pressure is dropping, impeller may be worn
• Loud buzz at cycle start, then silence — motor may be struggling to start, capacitor or motor winding issue
• Buzzing during fill phase — could be the water inlet valve struggling to open fully, especially if it's partially clogged with mineral deposits

A humming motor that's getting progressively louder over weeks is worth acting on before it fails completely mid-cycle.

😬 4. Squealing or High-Pitched Whining

A squeal that appears specifically during the drain phase — when the machine is pushing used water out — points directly to the drain pump.

What's happening: The drain pump motor has its own impeller and bearings separate from the main wash pump. When those bearings wear or the motor windings start to fail, you get a high-pitched whine under load.

Other causes of squealing:

• A worn door gasket creating friction as the door flexes slightly during pressure changes
• A hose or tube that's kinked and causing turbulence in the drain line

If the squeal is clearly coming from the bottom of the machine during drain — that's the pump. It won't get better on its own.

🔧 5. Rattling Throughout the Cycle

Rattling is usually not a mechanical failure — it's a loading or wear issue.

Common causes:

• Loose dishes — lightweight items like plastic containers aren't sitting securely and vibrate with the spray
• Worn wheels and rollers — rack wheels that are cracked or missing create an uneven, rattling rack that moves during the cycle
• Loose spray arm — if the arm isn't properly secured to its mount, it rattles as it spins
• Vibrating panels — on some machines, an outer panel screw works itself loose over time and the panel resonates during operation

What to do: Start by reloading and running a short cycle to confirm the sound is machine-side, not dish-side. Then check rack wheels and the spray arm mount.

💧 6. Knocking at the Start of a Fill

A sharp knock or thud right when the machine begins filling — before the cycle really starts — is almost always water hammer. This is a plumbing phenomenon, not a dishwasher malfunction.

It happens when the inlet valve opens or closes quickly and the sudden stop of flow creates a pressure shock through the supply line. You may notice the same knock in other appliances or fixtures in your home.

If the knocking is only at the dishwasher and appears gradually over time, the inlet valve itself may be partially failing — opening and closing inconsistently rather than smoothly.

⚡ 7. Clicking Sounds

Clicking at the start of a cycle or between wash phases is almost always the control board or relay switches doing exactly what they're supposed to do — switching components on and off as the cycle progresses.

When clicking becomes a concern:

• Rapid, repeated clicking that doesn't stop
• Clicking accompanied by the cycle failing to advance
• A burning smell alongside the clicking

In those cases, the control board or a relay switch may be misfiring rather than switching cleanly.

✅ How to Diagnose Systematically

1. Identify when the sound happens — fill, wash, drain, or randomly
2. Locate where it's coming from — bottom of the tub, door area, or back panel
3. Check the obvious first — debris in the tub, loose dishes, spray arm position
4. Clean the filter — debris that makes it past the filter ends up in the pump
5. Run a short cycle and listen closely — empty machine, door slightly ajar if safe, to isolate the source
6. Match the sound to the phase — grinding during wash = pump/bearings; whining during drain = drain pump; knocking at fill = inlet valve

Most dishwasher noises are fixable without a technician. The key is catching them early — before a worn bearing becomes a seized motor or a debris-clogged pump burns itself out.

❓ FAQ

My dishwasher has always been noisy — how do I know if something changed?

Trust your instincts. You've heard this machine hundreds of times. If a sound is new, louder, or has a different quality than before — investigate it. "It's always been like that" is only valid if it truly hasn't changed.

Can a noisy dishwasher damage dishes?

A banging spray arm or rattling rack can chip dishes over time. Grinding from debris in the pump can also cause secondary damage to the impeller if left unchecked.

 Is it safe to keep running a dishwasher that's making grinding noises?

Short answer: no. Grinding usually means something is caught in or wearing down a moving part. Continuing to run the machine risks turning a minor repair into a full pump or motor replacement.

The noise only happens at the end of the cycle — what is that?

End-of-cycle sounds are usually the drain pump clearing the last of the water, or the dispenser mechanism resetting. A brief gurgle or click is normal. A prolonged whine or grinding at drain phase points to the drain pump.

 Could a faulty sensor cause unusual sounds? Indirectly, yes. A turbidity or temperature sensor that's reading incorrectly can cause the machine to run cycles at wrong durations or pressures — which can make normal components sound louder or behave erratically.