A dishwasher making loud noise is telling you where to look: the type of sound and when it happens point to the cause. Here are the seven sounds I'm asked about most and what to do about each.
In this post:
- •Grinding
- •Knocking or thumping
- •Banging in the pipes
- •A steady hum while draining
- •Rattling during the drain
- •A rising squeal or whine
- •The whole unit rattles
1. Grinding
Something hard, like glass, a fruit pit or a bone, has reached the pump area, where the impeller chews on it.
How to tell: Grinding during wash or drain, often after a glass broke in the rack.
What to do: Turn off power at the breaker, remove the filter and check the sump carefully with gloves on. Pick out shards by hand or with tongs rather than reaching in blind.
2. Knocking or thumping
A spray arm is hitting something as it turns.
How to tell: A rhythmic knock during the wash, sometimes with dishes on one rack coming out dirty.
What to do: Spin each arm by hand after loading, and move tall items, pan handles or utensils that block its path.
3. Banging in the pipes
This is water hammer: a sudden bang when the inlet valve shuts off the flow and the moving water slams to a stop.
How to tell: The bang comes from the wall or under the sink as the fill ends.
What to do: A plumber can add a water hammer arrestor. It's a plumbing fix, not a dishwasher fault.
4. A steady hum while draining
The drain pump hums while it pushes water out. That's normal.
How to tell: A smooth hum during the drain that stops when the drain finishes.
What to do: Nothing, unless the hum continues and water stays in the tub.
5. Rattling during the drain
Debris has slipped past the filter and reached the drain pump.
How to tell: A rattle or chatter only while draining.
What to do: Clean the filter and sump. If it continues, the pump needs a technician.
6. A rising squeal or whine
A worn motor bearing or pump seal can squeal, and it usually gets louder over weeks.
How to tell: A high-pitched sound during the wash that's new or growing.
What to do: Book a technician before a worn seal starts leaking or the motor fails.
7. The whole unit rattles
The dishwasher isn't secured to the counter or cabinet, so the tub vibrates against them.
How to tell: The tub shifts when you pull the door or racks. A loose unit can also tip forward; see why a dishwasher door falls open.
What to do: With power off, tighten the mounting brackets and check that it's level.
When a technician is the better call
Squeals, grinding that comes back after cleaning, and drain pump noise with water left in the tub all need a pro. Describe the sound and when it happens, and our dishwasher repair team can usually pinpoint the source quickly.
Marco's advice: Note when the noise happens: fill, wash or drain. That one detail cuts diagnosis time more than anything else you can tell a technician.
Hearing something new? Call ProFix LA at (818) 334-4526.