Loud hum right after you start a cycle
You hear filling, then a strong hum or buzz, but the wash sound is weak or absent.
Start here: Look for a blocked filter, debris in the sump, or a circulation pump that is jammed or failing to start cleanly.
Dishwasher noise troubleshooting
LG Dishwasher Loud Humming? Drain & Pump Checks
Direct answer: If your LG dishwasher is making a loud humming noise, the most common causes are debris in the filter or sump area, a spray arm hitting something, a restricted drain path, or a circulation pump that is trying to run but is partly jammed or wearing out.
Most likely: Start by figuring out when the hum happens: right after startup usually points to the wash side, while a hum near the end of the cycle often points to the drain side.
A healthy dishwasher makes a steady wash sound and a brief drain sound. A loud hum, buzz, or strained motor sound is different. Reality check: one hard piece of debris in the wrong spot can make a dishwasher sound like a major failure. Common wrong move: running it again and again with standing water or a jammed spray arm, which can finish off a weak motor.
Don’t start with: Do not start by ordering a pump. A lot of loud humming complaints turn out to be glass, labels, seeds, or a loose item rubbing where it should not.
Hum starts during washCheck the lower spray arm, filter, and sump area first.
Hum happens during drainCheck for standing water, a clogged filter, air gap blockage, or a kinked dishwasher drain hose.
Last reviewed: 2026-04-30
What the loud humming usually sounds like
Hum near the end of the cycle
The dishwasher gets loud during drain periods, and you may find water left in the tub.
Start here: Check the filter, drain path, sink air gap if you have one, and the dishwasher drain hose for blockage or kinks.
Hum with a rhythmic ticking or rubbing
The noise rises and falls as the spray arm turns, or it sounds like plastic clipping something.
Start here: Inspect both dishwasher spray arms and make sure no tall utensil, pan handle, or fallen item is hitting them.
Hum gets louder over time
The machine still runs, but the motor sound is harsher than it used to be and cleaning may be getting worse.
Start here: After clearing blockages, suspect a worn dishwasher circulation pump if the noise stays during the wash portion of the cycle.
Most likely causes
1. Debris in the dishwasher filter or sump area
This is the most common cause of a strained hum after startup. Small bones, glass chips, labels, and food scraps can partially block water flow or rub the impeller area.
Quick check: Remove the lower rack and filter, then look for debris down in the sump with a flashlight.
2. Dishwasher spray arm hitting dishes or damaged from heat
A spray arm that cannot spin freely can sound like a motor problem because the pump is working against poor flow and the arm may click or scrape as it turns.
Quick check: Spin each spray arm by hand and look for cracks, melted spots, or anything sticking up into its path.
3. Restricted dishwasher drain path
A loud hum during drain, especially with water left in the bottom, usually means the drain side is pushing against a clog or kink.
Quick check: Check for standing water, then inspect the filter, sink air gap if present, and the visible run of the dishwasher drain hose.
4. Worn or partly seized dishwasher circulation pump
If the hum is strongest during the wash portion, cleaning is weak, and simple blockage checks are clear, the circulation pump is a strong suspect.
Quick check: Run a short cycle with the toe kick off if accessible and listen for the noise source low in the center of the machine during wash, not just during drain.
Step-by-step fix
Step 1: Pin down when the humming happens
You will save time by separating wash-side noise from drain-side noise before taking anything apart.
- Start a normal cycle and stay nearby for the first several minutes.
- Listen for three moments: fill, wash circulation, and drain.
- Note whether the loud hum starts right after filling, only during drain, or all through the cycle.
- Open the door briefly after the hum starts if safe to do so and check whether water is actively spraying inside or just sitting in the bottom.
If that issue is confirmed: Dishwasher keeps draining
What to conclude: A hum during wash usually points to circulation trouble or a blockage around the filter and sump. A hum during drain points more toward a clogged drain path or drain hose restriction.
Stop if:
- You smell burning insulation or hot electrical odor.
- Water starts leaking onto the floor.
- The dishwasher trips the breaker or loses power repeatedly.
Step 2: Check the spray arms and anything they can hit
This is a fast, low-risk check that often explains a noise that sounds worse than it is.
- Pull out the lower rack and look for utensils, pan handles, bottle caps, or fallen pieces that could contact a spray arm.
- Spin the lower dishwasher spray arm by hand and make sure it turns freely without wobbling or scraping.
- Check the upper dishwasher spray arm the same way.
- Look for split seams, melted spots, or clogged spray holes that could throw the arm off balance.
- Reposition dishes so nothing hangs below the rack line into the spray path.
Next move: If the hum or rubbing noise is gone on the next cycle, the problem was interference or a damaged spray arm. Move to the filter and sump check. A clear spray path with the same loud hum usually means the restriction is lower in the machine.
What to conclude: A blocked or damaged dishwasher spray arm can create a repeating hum, click, or grind and can also make cleaning performance drop.
Step 3: Clean the dishwasher filter and inspect the sump area
This is the highest-payoff check for a loud hum during wash or drain, and it often fixes the problem without parts.
- Turn off power to the dishwasher before reaching into the sump area.
- Remove the lower rack and take out the dishwasher filter assembly.
- Wash the filter with warm water and mild soap. Use a soft brush only if needed.
- Shine a flashlight into the sump area and remove food sludge, labels, glass fragments, or hard debris carefully.
- Check that the filter seats correctly when reinstalled and is not cross-threaded or loose.
Next move: Run a short cycle. If the hum is gone or much quieter, the blockage was starving the pump or rubbing near the impeller area. If the wash hum stays strong with a clean filter and clear sump, the circulation pump moves higher on the list. If the drain hum stays and water remains, check the drain path next.
Step 4: If the hum happens during drain, check the drain path
A drain-side hum with standing water is usually a blockage problem before it is a failed internal part.
- Look for standing water in the bottom of the tub after canceling or after the cycle ends.
- If your sink has an air gap, remove the cap and clear debris from inside.
- Inspect the visible run of the dishwasher drain hose for kinks, crushing, or a low spot packed with sludge.
- Disconnect and flush the dishwasher drain hose only if you can do it without spilling water into cabinets or onto flooring.
- Reinstall the hose with a smooth path and no sharp bends.
Next move: If the dishwasher drains normally and the hum is gone, the restriction was in the drain path, not the motor itself. If the drain path is clear but the machine still hums and leaves water, the problem may be deeper in the pump area and is a good point to stop and inspect further or call for service.
Step 5: Act on the confirmed pattern instead of guessing
By this point you should know whether you fixed a blockage, need a simple replacement part, or are dealing with a motor-level problem.
- If a spray arm is cracked, warped, or rubbing even with proper loading, replace the dishwasher spray arm.
- If the filter is damaged, will not lock in place, or stays loose after cleaning, replace the dishwasher filter assembly.
- If the drain hose is kinked, split, or still restricted after cleaning, replace the dishwasher drain hose.
- If the loud hum is clearly from the wash portion with a clear filter, free spray arms, and no drain issue, plan on replacing the dishwasher circulation pump or having a technician confirm it before ordering.
- After any repair, run a short cycle empty and listen through fill, wash, and drain to confirm the noise is gone.
Repair guide: How to Replace a Dishwasher Spray Arm
Related repair guide: How to Replace a Dishwasher Filter Assembly
A good result: You have matched the repair to the actual failure instead of throwing parts at the dishwasher.
If not: If the noise remains after the supported checks and simple part fixes, stop there and get a service diagnosis. At that point the issue may be deeper in the pump housing or another internal component.
What to conclude: The right next move depends on the exact sound timing and what you found. The simple parts are worth replacing when you have a visible defect. A persistent wash-side hum after clear checks strongly supports a circulation pump problem.
Replacement Parts
Dishwasher drain hose on Amazon
Dishwasher filter assembly on Amazon
Dishwasher spray arm on Amazon
Dishwasher circulation pump on Amazon
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FAQ
Why is my dishwasher humming but not spraying water?
That usually points to a wash-side flow problem. Start with the dishwasher filter, sump area, and spray arms. If those are clear and the hum starts right after filling, the dishwasher circulation pump may be jammed or wearing out.
Can a clogged filter make a dishwasher sound like the motor is bad?
Yes. A packed dishwasher filter or debris in the sump can make the motor sound strained, louder, and rougher than normal. That is why the filter and sump check comes before pump replacement.
Why does the humming only happen when the dishwasher drains?
A hum during drain usually means the drain side is pushing against a restriction. Check for standing water, a clogged filter, a blocked sink air gap, or a kinked dishwasher drain hose before assuming an internal failure.
Is it safe to keep running a dishwasher that makes a loud humming noise?
Not for long. One short test cycle is reasonable for diagnosis, but repeated runs with a jammed spray arm, blocked sump, or struggling pump can make the damage worse.
Should I replace the pump first if the noise is really loud?
No. Loud does not automatically mean failed pump. Spray arm interference, sump debris, and drain restrictions are more common and much cheaper to fix. Replace the pump only after the simple checks are clear and the noise pattern supports that call.
What if the dishwasher hums and leaves water in the bottom?
Treat that as a drain-path problem first. Clean the filter, check the air gap if you have one, and inspect the dishwasher drain hose for kinks or sludge buildup. If the drain path is clear and the problem stays, then deeper pump inspection makes sense.