Dishwasher Making Grinding, Humming, or Groaning Noise? 6 Quick Fixes

Fix your dishwasher’s grinding, humming, or groaning noises. Includes general troubleshooting for all brands and specific repair guides for DIYers.

Quick Fixes for Dishwasher Noises

• Clear the Filter: Remove and rinse the cylindrical filter at the bottom of the tub to clear trapped glass shards or debris causing grinding sounds.
• Check Spray Arm Path: Manually spin the upper and lower spray arms to ensure they aren’t hitting tall plates or fallen utensils (the #1 cause of thumping).
• Inspect the Sump: Look inside the sump housing (under the filter) for hard objects like popcorn kernels or fruit pits that can rattle against the impeller.
• Verify Water Level: Ensure the dishwasher is filling completely; a low water level causes the pump to suck in air, creating a loud humming or whistling.
• Level the Unit: Check that the dishwasher is level. An unlevel unit causes the tub to warp slightly, leading to vibrations or the spray arms scraping the walls.
• Perform a Hard Reset: Disconnect power at the breaker for 60 seconds to clear electronic “glitches” in the motor control board that can cause erratic humming.

Dishwasher Noise Diagnostic Table

Dishwasher making grinding noise

Some dishwashers make grinding noises as they go through a cycle. And sometimes, this noise is normal if the dishwasher’s electronic control panel has a motor-driven switching device, but the grinding shouldn’t be too loud.

Groaning: the dishwasher’s motor is struggling under load. If the grinding suddenly gets too loud, inspect the dishwasher because the cause could be:

Clogged pump or chopper blade area

Typically, the cause of grinding noises is a foreign object stuck inside the rotating plastic blades of the dishwasher. This could have happened during cleaning; a hard food item or piece of the dishes broke and fell straight into the bottom of the machine then got lodged around the dishwashers drain impeller.

How to inspect the pump or chopper blade area:

• Safety First: Disconnect the dishwasher from the power outlet or turn off the circuit breaker.
• Access the Bottom: Open the door, let the steam clear, and remove the racks. You can then access the bottom and unscrew the lower spray arm unit off.
• Clean the Screen and Filter: Remove the dishwasher screen (located below the lower spray arm) and wash the filter with soap and water to remove grease and debris.

• Open the Pump Housing: Remove the plastic pump housing cap to reveal the internal components.
• Inspect the Grinder Area: Unscrew the upper impeller to reach the food grinder blade and clear any debris or food chunks trapped around the chopping blade.
• Reassemble: Check for worn-out parts to replace, then reinstall all components in the reverse order.

Insufficient water supply into the dishwasher

Check the water inlet valve for clogs or other issues that may be preventing water from entering the dishwasher. Make sure the water lines are free of kinks or restriction.

About this: The water inlet valve is the connecting point between the dishwasher and your household plumbing. It’s a mechanical valve that opens at the beginning of a new dishwashing cycle to let the water fill the appliance. Once there’s enough water inside, the valve will shut entirely and stop any more water from entering.

Depending on your chosen cycle, you might hear the water inlet valve opening more than once. That will happen any time the appliance needs more clean water to function.

How it grinds or groans: A water inlet valve in excellent condition will open or close fully and never halfway. Unfortunately, you’ll hear the grinding or groaning sound when the valve is only partially open. That partial opening forces the water to rush through only a tiny opening, which can cause the noises you hear.

How to fix it: Firstly, you must inspect the water inlet valve closely. A foreign object is likely to be stuck inside, preventing the valve from fully opening or closing.

Besides that, you can also check around the valve’s openings for dirt, debris, or rust buildups. Those can also prevent the valve from opening and shutting correctly.

Read Also: Amana Dishwasher Noises Troubleshooting Guide

Dishwasher making a Loud Humming Noise or high-pitched sound

If your dishwasher is making loud droning noise during operations, then the likely cause is that the bearings on the circulation pump have gone bad.

Circulation pump issue

About this: Your LG dishwasher has at least 2 water pumps inside. One is the circulation pump, which is crucial for cleaning your dishes.

As the name suggests, this pump is responsible for circulating water throughout your LG dishwasher. More specifically, it takes water in and drives it through the wash arms, so all your kitchenware gets washed.

The circulation pump spins an impeller at high speeds to make water move. That spinning is supported by bearings inside the motor that allow it to turn the impeller with no friction or noise being produced.

How it grinds or groans: The circulation pump will run throughout every wash cycle that you begin on your LG dishwasher. That means the pump and bearings are constantly under stress and will wear out with extended use.

If the pump motor bearings are faulty, water pressure won’t be generated through the spray arms. Replacing the motor and pump should fix the problem and stop the continuous drone-like sound as well.

When the bearings start to wear out, they’ll prevent the motor from turning the impeller smoothly and without noise. Instead, the motor will produce a grinding or groaning noise as it struggles to work correctly.

How to fix it: Unfortunately, the bearings inside the circulation pump motor can’t be replaced separately. So, if the one in your dishwasher is making lots of groaning and grinding noises, you’ll have to replace the entire pump with a new one.

Circulation Pump bearings:

Spray arms may be hitting the dishes

If the banging sound has a certain rhythm to it, then probably the spray arms are banging on the dishes. The reason for rhythmic banging is because spray arms usually rotate in a circle. Fix this banging dishwasher noise by readjusting the dishes.

But if the banging inside the dishwasher is non-rhythmic, you might want to call a plumber because you most likely are experiencing water hammer.

Dishwasher making humming noise during dry cycle

Ventilation Fan

Is your dishwasher making a loud humming noise, especially during the drying cycle? Then the most likely culprit is the drying fan. Fixing the fan should reduce the humming volume.

Fixes for a Dishwasher Not Drying

A dishwasher not drying is often a mechanical issue or a settings error. Check these components to get your dishes bone-dry:

• Select “Heated Dry”: Verify that the Heated Dry or High-Temp Wash option is selected before starting the cycle.
• Inspect the Heating Element: Look at the black circular tube at the bottom of the tub. If you see cracks, blisters, or a white mineral coating, it may need to be replaced.
• Test for Continuity: Use a multimeter to test the heating element and the high-limit thermostat. If either shows “infinite” resistance, it is faulty and preventing heat.
• Check the Vent and Fan: Amana dishwashers use a vent to release steam. If the vent is stuck closed or the small internal fan has failed, moisture will stay trapped on your dishes.
• Load for Drainage: Ensure cups and bowls are tilted at an angle so water doesn’t pool in the “wells” of the plasticware.

Dishwasher making noise when draining

So, your beloved quiet dishwasher machine goes through the wash cycle well, but when it comes to draining, it makes loud grinding, rubbing, or humming sound? The likely cause of noise during draining could be:

Drain pump issue

The second pump is the drain pump, located at the bottom of the dishwasher. This pump helps to drive used water out of the appliance and into your household drain.

The pump will run any time the dishwasher empties before refilling with clean water. On top of that, it’ll also run one final time at the end of a cycle to remove all remaining water inside. If something is lodged inside the sump unit or the drain pump is faulty, the dishwasher will make weird sounds during the drain cycle.

How it grinds or groans: Just like the circulation pump, the drain pump relies on bearings to spin an impeller. The bearings reduce friction so the motor can turn the impeller smoothly at high speeds without making noise. Similarly, the bearings here can also wear out. When they do, you’ll hear grinding or groaning noises coming from this motor instead.

You can try to turn the impeller manually to see if its movements are restricted by worn-out bearings. Check for debris around and inside the drain pump, and even if after cleaning the unit, the noise continues, replace the dishwasher’s drain pump.

How to fix it: You can’t repair or replace bearings in the drain pump motor separately either.

If your dishwasher is slow to drain, or there is regularly water at the bottom after the wash cycle, you likely need to replace the pump entirely.

Dishwasher making a strange rattling noise

When a dishwasher is running, rattling sounds are normal due to loose forks or dishes touching each other as they are jostled by water. Rattling or squealing is also normal if there’s no water in brand new dishwashers or if you have not used it in a long time. Adding some water to the tub should fix the issue.

Water pipeline hammer knock sound

Water hammer issue happens due to sudden valve shutting leading to rapid bursts of water to rattle pipes such that they bang against the surrounding. Use a water hammer arrestor to take care of water hammer issue.

Maintenance for a Dishwasher

• Clean the Filters: Remove the cylindrical filter at the bottom and rinse under hot water to remove grease and food particles.
• Unclog Spray Arms: Use a toothpick or wire to clear debris from the small holes in the upper and lower spray arms.
• Check Water Temperature: Your home’s hot water should be at least 120°F (49°C) for the detergent to activate correctly.
• Inspect the Inlet Valve: If the dishwasher doesn’t fill with enough water, the pump can’t create enough pressure to clean the dishes.

Frequently Asked Questions

How Noisy Should A Dishwasher Be?

A dishwasher typically operates at 40-60 decibels, depending on the model. However, those noise levels aren’t very high. Instead, they are similar to the gentle humming noise that typically comes from your refrigerator.

How Long Do LG Dishwashers Last?

You can expect your LG dishwasher to last 10-15 years with regular cleaning and maintenance. Typically, you’ll only face an increasing number of problems related to wear as the machine approaches the end of its lifespan.