The short answer
New noise from a BlueStar dishwasher is usually made by the load rather than by the machine. A pro-style tub takes tall and heavy items, and a platter or a long utensil in the arc of a spray arm produces a knock that sounds mechanical. Run the machine empty once; that single test eliminates most of the list below.
What you are seeing
- A regular knock in time with the spray arm
- A rattle that changes as the load shifts
- Grinding or crunching heard only during the drain step
- A hum that continues after water stops moving
- A steady whine throughout the wash phase
- A near-miss symptom: a bang in the pipework when the fill valve closes, which is water hammer in the house plumbing
- Body: The rhythm and the timing identify the source: A regular knock in time with the spray arm. A rattle that changes as the load shifts. Grinding or crunching heard only during the drain step. A hum that continues after water stops moving. A steady whine throughout the wash phase. A near-miss symptom: a bang in the pipework when the fill valve closes, which is water hammer in the house plumbing.
Causes, most likely first
- An item catching a spray arm — Why: a pro-style tub invites platters and long utensils, and anything crossing the arm produces one knock per revolution, which is the most common complaint by a wide margin.
- Items resonating against each other — Why: stainless and lightweight bowls buzz under the spray, and this is the noise most often mistaken for a bearing.
- Debris in the sump or drain chamber — Why: glass chips and fruit stones reach the impeller and grind during the drain step only, which is the timing clue.
- The machine contacting the cabinetry — Why: a heavy built-in that was shimmed tight against the counter transmits ordinary pump vibration into the whole run of units.
- A worn circulation-pump bearing — Why: a whine that is present with the tub empty and unchanged by loading, which is exactly what separates it from everything above.
- A failing drain pump — Why: a hum with no water moving, and it usually arrives alongside a drainage complaint rather than on its own.
- Body: Ranked for a large tub that takes oversized items: First, An item catching a spray arm: a pro-style tub invites platters and long utensils, and anything crossing the arm produces one knock per revolution, which is the most common complaint by a wide margin. Second, Items resonating against each other: stainless and lightweight bowls buzz under the spray, and this is the noise most often mistaken for a bearing. Third, Debris in the sump or drain chamber: glass chips and fruit stones reach the impeller and grind during the drain step only, which is the timing clue. Fourth, The machine contacting the cabinetry: a heavy built-in that was shimmed tight against the counter transmits ordinary pump vibration into the whole run of units. Fifth, A worn circulation-pump bearing: a whine that is present with the tub empty and unchanged by loading, which is exactly what separates it from everything above. Sixth, A failing drain pump: a hum with no water moving, and it usually arrives alongside a drainage complaint rather than on its own.
What to check, in order
- note whether the noise is during the wash, the drain, or both, since that splits the causes immediately.
- run the machine empty: any noise that disappears was a loading problem.
- if the noise is confined to the drain, look for debris in the sump chamber.
- a whine on an empty machine unchanged by loading is mechanical, and that is where the owner checks end.
- Body: Use timing and an empty run, both of which are free: First, note whether the noise is during the wash, the drain, or both, since that splits the causes immediately. Second, run the machine empty: any noise that disappears was a loading problem. Third, if the noise is confined to the drain, look for debris in the sump chamber. Fourth, a whine on an empty machine unchanged by loading is mechanical, and that is where the owner checks end.
Checks you can do yourself
- Cancel the programme, open the machine and check whether anything stands in the arc of a spray arm — Tools: none — Time estimate: a few minutes
- Reload with tall items at the sides and nothing hanging below the upper basket, then rerun — Tools: none — Time estimate: an hour or more
- Switch off at the breaker, lift out the filter and check the sump chamber for glass and stones — Tools: torch, gloves — Time estimate: a few minutes
- Spin each spray arm by hand and listen for roughness at its bearing — Tools: none — Time estimate: a few minutes
- Run a full programme with the tub completely empty and note whether the noise remains — Tools: none — Time estimate: an hour or more
- Body: One empty run tells you more than any inspection: Cancel the programme, open the machine and check whether anything stands in the arc of a spray arm (none; a few minutes). Reload with tall items at the sides and nothing hanging below the upper basket, then rerun (none; an hour or more). Switch off at the breaker, lift out the filter and check the sump chamber for glass and stones (torch, gloves; a few minutes). Spin each spray arm by hand and listen for roughness at its bearing (none; a few minutes). Run a full programme with the tub completely empty and note whether the noise remains (none; an hour or more).
Safety first
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Broken glass is the usual find in a sump chamber, so wear gloves and use a torch rather than feeling for it. Cancel the programme and let the machine drain before opening the door on a hot cycle. unplug-before-service
When to stop and call a technician
Mechanical noise needs a technician: The noise is unchanged with the tub empty and the sump clear. Grinding persists after the sump chamber has been cleaned. The noise arrives with poor drainage or a fault code. A metallic scrape that worsens over successive cycles. The noise is unchanged with the tub empty and the sump clear Grinding persists after the sump chamber has been cleaned The noise arrives with poor drainage or a fault code A metallic scrape that worsens over successive cycles
Nearest pages of the same kind
What this page does not cover
This page is generalized across every dishwasher sold under the BlueStar name: it separates neither the panel-ready cabinets from the stainless-fronted ones and one control generation from another, and it names no individual model. Where a family- or model-specific page exists it is linked here and it outranks this one for that machine; at present no page beneath this one narrows to a single family, so treat the ranking above as the brand-level pattern rather than a reading of your serial plate. For the other faults that turn up on this machine, start from Common BlueStar Dishwasher Problems.
Related pages
- Common BlueStar Dishwasher Problems
- BlueStar Dishwasher: Does Not Clean or Dry
- BlueStar Dishwasher: Controls, Display or Error Code
- BlueStar Dishwasher: Cycle Will Not Run or Complete
- BlueStar Dishwasher: Door, Latch or Seal Fault
- BlueStar Dishwasher: Will Not Drain
- BlueStar Dishwasher: Electrical, Fire or Gas Hazard
- BlueStar Dishwasher: Not Heating
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
