The most common reason for a scraping noise is a foreign object (glass shard, bone, label, seed) trapped in the sump area and contacting the grinder screen/chopper or the circulation pump impeller. It happens when debris slips past the filter or the filter is installed incorrectly. First action: stop the cycle, remove the lower rack, pull the filters, and inspect the sump for hard debris you can feel or see.
Identify the Noise First
Foreign-object scraping in the sump is most noticeable when water is moving fast through the sump. That usually means the noise is tied to spray/circulation, not fill.
During water fill: If the scraping starts with incoming water only and stops once filling ends, it is less consistent with sump scraping. Confirm by pausing after fill; if the noise disappears when circulation begins later, look elsewhere.
During spray / circulation: If the scraping starts shortly after the tub fills and the spray arms begin, this strongly points to an object contacting the impeller/chopper area in the sump.
During draining: If the scraping only happens when you hear the drain pump running (usually a single steady tone with rushing water), it may be an object at the sump outlet being pulled toward the pump. Note whether the sound stops the moment draining stops.
During heating: If the noise appears during a quiet period between washes (no spray sound), it is unlikely to be sump scraping. Sump-related scraping needs pump movement.
At start of cycle: Many units do a brief drain at the start. Scraping only in that first minute suggests debris shifting at the sump/drain intake area, not during extended wash.
At end of cycle: End-of-cycle drain scraping can happen if debris migrates during the final rinse and gets pulled to the sump outlet during the last drain.
Constant: A continuous scrape that persists through all pump-on periods suggests a hard object stuck in a position where it repeatedly contacts the rotating parts.
Intermittent: A scrape that comes and goes during spray often means the object is tumbling in the sump and only occasionally hitting the impeller/chopper.
To isolate the stage: start a cycle and listen for the sequence. You should hear fill (water entering), then a change to a more forceful “whoosh” as circulation starts. If the scraping begins with that transition, focus on the sump.
What This Noise Usually Means
The sump is the low basin under the filters where wash water collects before the circulation pump pulls it through the impeller and (on some designs) past a chopper/grinder screen. A hard foreign object in the sump can get pulled into the rotating water stream and dragged across plastic housings, the stainless filter screen, or the impeller blades. The sound is typically a sharp scrape, tick-scrape, or grinding scrape that changes pitch as the pump speed/load changes.
Most Common Causes
Glass shard in the sump well: Broken glass bypasses the filter during a previous cycle and settles where the pump intake swirl can pick it up.
Bone pit, popcorn kernel, seed, or hard food fragment: These “round hard” items roll and intermittently contact the impeller or chopper cover, creating a repeating scrape.
Paper label or plastic film partially lodged under the filter: It can flutter, then get caught and dragged against moving parts, alternating between quiet and scraping.
Filter not seated or locked: A loose filter lets debris enter the sump and can also allow the filter frame to vibrate against the sump opening, mimicking scraping that tracks pump operation.
Foreign object wedged at the sump outlet path: Small pieces can sit near the port between sump and pump intake and get pulled into contact when circulation ramps up.
How to Check Safely
1) Confirm cycle stage
Run the dishwasher for a few minutes and listen for the shift from fill to circulation.
If the scraping begins only when spray/circulation starts, proceed with sump inspection.
2) Isolate load factor
Stop the cycle and open the door.
Check for loose items that could drop into the sump area (small lids, toothpicks). Remove anything questionable and re-seat the racks.
Do not run the unit with missing filters or intentionally “empty” of filters to test.
3) Inspect relevant components
Turn the dishwasher off at the controls. If you will put hands into standing water or reach into the sump, switch power off at the breaker as well.
Remove the lower rack.
Remove the lower filter assembly (typically a twist-lock cylinder and a flat screen). Note how it indexes so you can reinstall it correctly.
4) Confirm or rule out obstruction
Visually inspect the sump well with a flashlight.
Look specifically for glass, bone fragments, labels/film, or small hard objects.
Carefully remove debris by hand or with needle-nose pliers. Use cut-resistant gloves if you suspect glass.
Wipe the sump area and the underside of the filter screen; confirm nothing is trapped around the intake opening.
Reinstall filters fully seated and locked. A filter that sits high or rocks is not installed correctly.
5) Perform controlled test
Restore power.
Run a short cycle and listen for the first 3–5 minutes of circulation.
If the scraping is gone, the obstruction was the cause. If it persists unchanged, stop the cycle and do not continue repeatedly running it; persistent scraping can damage the impeller.
When This Is Normal vs A Problem
Normal: A steady “wash whoosh” during circulation and occasional soft ticking from spray arms misting over dishes. Brief, light contact sounds that stop immediately after you reposition a loose utensil usually point to load contact, not the sump.
A problem: A sharp scraping or grinding scrape that starts with circulation and repeats consistently, especially if it gets louder over the cycle. Any scraping that returns quickly after you clean the filters suggests debris is still in the sump or the filter is not sealing and is allowing more debris through.
When to Call a Technician
You removed the filters and cannot locate any debris, but the scraping continues during circulation.
The noise is accompanied by poor wash performance (weak spray) right after the scraping began, suggesting the obstruction is still interfering with flow at the sump intake.
The filter housing is damaged, won’t lock, or won’t sit flush, allowing recurring debris entry.
You suspect glass is embedded where you cannot safely reach without disassembly.
How to Prevent This Problem
Rinse off hard items that commonly fall into the sump: seeds, bones, toothpicks, broken skewers.
After cleaning the filter, always lock it fully; a partially seated filter is a common reason debris reaches the sump.
If a glass breaks, do not run another cycle until you remove racks, pick out shards, and clean the filters and sump well by hand.
Periodically remove and rinse the filter screen so labels and film can’t migrate under it.
Related Dishwasher Noise Problems
Spray arm scraping or ticking because the arm is hitting a tall pan or utensil
Grinding noise from a damaged circulation impeller (after a foreign object incident)
Chattering/rattling from loose filter assembly or filter not locked in place
Thumping from a large item shifting and contacting the lower spray arm during circulation
Buzzing during drain from debris at the drain intake (similar timing confusion with sump debris)
Conclusion
A scraping noise that begins when circulation starts is most often a foreign object in the sump contacting the impeller/chopper area. Confirm the timing, remove the lower rack and filters, and inspect the sump with a light. Remove debris and reinstall the filter correctly, then run a short controlled test to verify the noise is gone.
Frequently Asked Questions
Can I keep running the dishwasher if it’s scraping?
No. If the scrape tracks pump operation, you risk scoring the sump housing or damaging the impeller. Stop the cycle, remove the filters, and check the sump before running it again.
Why did the scraping start after I cleaned the filter?
Most often the filter was not seated or locked, letting debris reach the sump, or a piece of debris was dislodged during cleaning and dropped into the sump well. Recheck that the filter is fully engaged and inspect the sump for a small shard or hard fragment.
What’s the fastest way to tell sump scraping from spray-arm contact?
Spray-arm contact usually changes or stops when you rearrange the load and it may sound higher in the tub. Sump scraping is lower, harsher, and starts exactly with circulation even with the racks empty of loose items, because the sound is generated under the filter area.
I removed debris but still hear a light scrape for a few seconds after start-up. Is that normal?
A brief sound right at the start of circulation can be leftover debris shifting before it settles. If it disappears and does not return in the same cycle, monitor it. If it repeats throughout the wash, something is still in the sump area or the filter is not sealing correctly.
Can a paper label really cause a scraping noise?
Yes. A label or thin plastic film can get pulled against the filter screen or intake area and make a dragging/scraping sound that comes and goes. Remove the filters and check the underside of the screen and the sump well for stuck material.
That’s the part people don’t always say out loud: getting to the point where it all makes sense feels like exhaling. The noise fades, and the page suddenly reads like it was always meant to be read.
From here, it’s less about chasing answers and more about living in the same world with one less friction point. Small, steady, and oddly satisfying—like finding your keys on the first try.
