Grinding starts after the tub fills
You hear the noise once the wash action begins, often from the center or bottom of the tub.
Start here: Check for a blocked dishwasher filter, debris in the sump, or a spray arm hitting dishes.
Dishwasher noise troubleshooting
Dishwasher Grinding Noise
Direct answer: A dishwasher grinding noise is most often hard debris caught in the filter or sump, a spray arm clipping a tall item, or debris reaching the wash or drain impeller. If the sound is a harsh, steady grind during wash with the racks clear, the wash pump moves up the list. If it happens only during drain, stay on the drain path before blaming the wash pump.
Most likely: Start by figuring out when the grinding happens: right after fill, during spray, or during drain. That timing usually tells you whether you are dealing with debris, a spray arm strike, a drain restriction, or a pump problem.
Reality check: light swishing and brief pump sounds are normal, but a true grinding or gravelly noise is not. Common wrong move: running repeated cycles to 'see if it clears' can chew up an impeller if something hard is already in there.
Don’t start with: Do not start by ordering a pump. A lot of grinding complaints turn out to be glass chips, a seed, a bone fragment, a twist tie, a loose filter, or one tall utensil hitting the spray arm.
Grinding only during drain?Check the dishwasher filter, sump area, drain path, and any sink air gap before blaming the motor.
Grinding during wash with dishes loaded?Look for a loose dishwasher spray arm or tall items getting clipped before opening up anything deeper.
Last reviewed: 2026-05-13
What the grinding noise sounds like and when you hear it
Grinding happens near the end when it drains
The machine sounds rough only during pump-out, and you may also notice slow draining or leftover water.
Start here: Check the dishwasher filter, drain opening, drain hose path, disposal inlet, and sink air gap if you have one.
Grinding changes when the racks are loaded
The sound is worse with tall pans, utensils, or a cutting board in the lower rack.
Start here: Look for the lower dishwasher spray arm clipping dishes or a loose spray arm hub.
Grinding is constant and harsh every cycle
The noise does not care whether the dishwasher is full or empty and keeps coming back from the lower front or sump area.
Start here: After clearing debris and checking the spray arms, suspect a failing dishwasher wash pump.
Most likely causes
1. Hard debris in the dishwasher filter or sump area
This is the most common cause, especially after a broken glass, popcorn kernel, fruit pit, bone chip, or label fragment gets past the screen.
Quick check: Remove the lower rack and filter, then look for glass chips, seeds, twist ties, labels, broken plastic, or anything sitting around the pump opening.
2. Dishwasher spray arm hitting dishes or a loose spray arm
A lower spray arm that clips a pan handle or tall utensil can sound like grinding from outside the door.
Quick check: Spin the spray arms by hand with the racks loaded the way you normally run them and feel for contact.
3. Restricted drain path making the dishwasher drain pump sound rough
If the noise shows up mainly during drain, the pump may be chewing on debris or straining against a blockage downstream. This is especially likely after disposal replacement or under-sink drain work.
Quick check: See whether there is standing water after the cycle and inspect the drain hose loop, sink air gap, and disposal or tailpiece connection for blockage.
4. Worn or damaged dishwasher wash pump impeller or bearings
A steady mechanical grind during wash, especially in an empty machine after debris has been cleared, points to the wash pump itself.
Quick check: Run a short rinse cycle with the racks mostly empty after cleaning the filter area. If the same harsh grind returns during spray, the wash pump is likely failing.
Step-by-step fix
Step 1: Pin down exactly when the grinding happens
Noise timing tells you more than volume. Wash noise and drain noise are different problems most of the time.
- Start a short cycle and stay nearby for the first few minutes.
- Listen for three points: initial fill, active spraying, and drain-out.
- Note whether the sound comes from inside the tub, the lower front kick area, or near the sink drain, disposal, or air gap.
- Compare wash-phase noise with drain-only noise so you do not chase the wrong pump.
- Cancel the cycle if the noise becomes sharp, metallic, or much louder than usual.
If that issue is confirmed: Dishwasher door not latching
What to conclude: Grinding during wash usually points to debris in the sump, a spray arm strike, or a failing wash pump. Grinding during drain leans toward debris in the drain side, a blocked drain path, or a failing drain pump.
Stop if:
- You smell burning insulation or hot plastic.
- Water starts leaking onto the floor.
- The dishwasher trips power or goes dead mid-cycle.
Step 2: Check the racks and spray arms before taking anything apart
A lot of 'grinding' is really the lower spray arm smacking a pan, utensil, or fallen lid.
- Turn power to the dishwasher off or open the door and stop the cycle.
- Pull out the lower rack and look for tall utensils, pan handles, bottle caps, or small items that could reach into the spray arm path.
- Spin the lower dishwasher spray arm by hand. It should turn freely without wobbling or scraping.
- Check that the spray arm is seated firmly and not split, drooping, wobbling, or packed with debris.
- Reload anything tall so it sits below the spray arm path.
Next move: If the noise disappears after reloading or reseating the spray arm, you found the problem and no deeper repair is needed. If the spray arms clear everything and still spin rough or the noise happens from below, move to the filter and sump check.
What to conclude: Contact marks on dishes or a spray arm that wobbles point to a dishwasher spray arm issue. A clear spray path with the same grinding noise points lower into the sump or pump area.
Step 3: Clean the dishwasher filter and inspect the sump for hard debris
This is the highest-payoff check. Small hard debris can make a terrible noise and is often visible once the filter is out.
- Shut off power to the dishwasher at the breaker or unplug it if accessible.
- Remove the lower rack and take out the dishwasher filter assembly according to its locking tabs.
- Rinse the dishwasher filter with warm water and mild soap if it is greasy or packed with food.
- Use a flashlight to inspect the sump area around the pump opening for glass chips, seeds, labels, toothpicks, twist ties, broken plastic, or bone fragments.
- Inspect the filter for cracked plastic, torn mesh, or missing locking tabs that could let debris keep bypassing it.
- Carefully lift out visible debris by hand or with needle-nose pliers. Wipe the area clean with a damp cloth.
- Reinstall the dishwasher filter securely so it locks flat and does not sit crooked.
Next move: If the grinding is gone on the next short cycle, the debris or clogged filter was the cause. If the noise is still there, pay attention to whether it now happens only during drain or still during wash.
Step 4: If the noise is during drain, check the drain path for blockage
A dishwasher that grinds only while pumping out is often fighting debris in the drain side, not failing during wash.
- Look for standing water in the bottom after canceling or finishing a cycle.
- Inspect the dishwasher drain hose for a kink, low sag, crushed section, or food sludge near the connection point.
- If your sink has an air gap, remove the cap and clean out any gunk inside.
- Check the disposal inlet or sink drain connection point for buildup if the dishwasher recently started draining poorly.
- If the noise started after a new disposal or sink drain work, confirm the dishwasher connection is open and the hose was not pinched or rerouted too low.
- Run a short drain test after clearing any visible blockage.
Next move: If the drain noise stops and water leaves quickly, the rough sound was from a restricted drain path or debris at the drain side. If it still grinds only during drain after the path is clear, the dishwasher drain pump may have debris or internal damage and is a good pro-level next check.
Step 5: Test for a failing wash pump and decide whether to repair or call it
Once the easy causes are ruled out, a repeatable harsh grind during wash usually means the dishwasher wash pump is worn or damaged.
- Reassemble the filter and racks, then run a short rinse cycle with the dishwasher mostly empty.
- Listen for a steady grind once the spray action starts.
- Open the door briefly to stop the spray, then close it again. If the same harsh grind returns immediately with circulation, the wash pump is the likely source.
- If the only confirmed issue was a damaged or loose dishwasher spray arm, replace that part.
- If the filter was broken and would not lock in place, replace the dishwasher filter assembly.
- If the grind clearly comes from the pump area after debris is cleared, stop repeated testing and schedule a pump diagnosis or replacement.
- If draining is normal but wash circulation stays noisy, focus on the circulation pump rather than the drain pump.
Repair guide: How to Replace a Dishwasher Filter
A good result: If replacing the damaged spray arm or filter fixes the noise, run a full cycle and put the dishwasher back in service.
If not: If the wash grind stays after cleanup and simple part fixes, the practical next move is a wash pump repair by someone comfortable pulling the unit and working around water and wiring.
What to conclude: A repeatable wash-phase grind from the sump area after cleanup is strong evidence of a failing dishwasher wash pump. That is a real fault, not a normal dishwasher sound.
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FAQ
Is a grinding noise in a dishwasher normal?
No. Light swishing, water spraying, and a soft hum are normal. A true grinding, gravelly, or metal-on-plastic sound usually means debris, a spray arm strike, or a failing pump.
Can broken glass make my dishwasher sound like the motor is bad?
Yes. A few glass chips in the filter or sump can sound a lot worse than they look. That is why the filter and sump check comes before any motor or pump guess.
Why does my dishwasher only grind during drain?
That usually points to the drain side. Start with the filter, drain opening, drain hose, disposal or tailpiece connection, and sink air gap if you have one. If the path is clear and it still grinds only during drain, the drain pump may be damaged.
Why does the noise get worse when the dishwasher is full?
Loaded racks can change the spray arm path. A tall utensil, pan handle, or cutting board can get clipped by the lower spray arm and sound like a grinding motor from outside the door.
Should I keep running it to flush the noise out?
No. If something hard is in the pump area, repeated cycles can damage the impeller. Stop, clean the filter and sump, and only retest after the obvious debris is cleared.
When is the wash pump the likely problem?
After you have ruled out spray arm contact, cleaned the filter, and removed visible debris, a steady harsh grind that returns every time the wash action starts points strongly to the dishwasher wash pump.
Can a new garbage disposal cause dishwasher grinding during drain?
Indirectly, yes. If the dishwasher drain connection is blocked, packed with debris, or the hose is kinked after disposal work, the dishwasher pump can sound strained during drain. Check the under-sink connection before replacing dishwasher parts.