Dishwasher Making Loud or Strange Noises: Causes and Solutions

A dishwasher is expected to operate quietly. When it begins producing loud or unusual sounds, it usually signals a problem. Some noises come from simple issues such as poor loading of dishes, while others may indicate serious faults inside the machine. Below we will break down the most common types of noises, why they appear, how you can check the issue on your own, and when it is best to contact a professional technician.

1. Humming or Buzzing

Why it happens: A steady humming sound often comes from the circulation pump or motor. It may indicate worn bearings, low water level in the tub, or the pump working under high load. Sometimes light buzzing during drain is normal, but a loud constant hum points to trouble.

How to check: Open the door a few minutes after the wash starts and make sure the water level is just below the bottom of the door opening. Inspect and clean the filter, and verify that the spray arms can move freely without resistance.

When to call a technician: If the humming is continuous and strong even after cleaning the filter and ensuring proper water level, the circulation pump or motor may be failing and needs replacement.

2. Grinding or High Pitched Squeal

Why it happens: This noise is usually caused by foreign objects such as bones, glass fragments, or seeds that fall into the sump and hit the chopper blade. It can also appear when the chopper itself is damaged or when pump seals are worn.

How to check: Remove the bottom rack, take out the filter and sump cover, and carefully inspect for debris. Clean the parts and flush them under running water to ensure nothing is blocking the impeller.

When to call a technician: If the grinding or squealing continues after cleaning, the chopper blade, impeller, or pump assembly may be damaged. These parts require professional replacement.

3. Rattling, Banging or Thumping

Why it happens: These sounds often result from dishes or utensils that are not loaded correctly. Spray arms can strike tall items, or pans with long handles may hit the side of the tub. In some cases a loose inlet valve or a water hammer in the supply line can also create loud bangs.

How to check: Rearrange the dishes so that spray arms spin freely without touching objects. Check that the machine is level and does not rock when you push on the corners. Inspect the inlet hose for secure attachment.

When to call a technician: If the banging noise repeats even with no dishes inside, the spray arm may be warped or the inlet valve may be failing. In this case professional inspection is required.

4. Loud Noise During Drain

Why it happens: The drain pump may be clogged or running dry, or the drain hose may have a blockage. A broken or worn impeller can also make the pump produce harsh buzzing or grinding sounds.

How to check: Remove and clean the drain filter. Inspect the drain hose and air gap for clogs. Ensure that the hose is not kinked or pinched behind the dishwasher.

When to call a technician: If the pump continues to buzz loudly and water does not drain properly, the impeller or the entire drain pump assembly may need replacement by a specialist.

5. Popping or Sharp Knocking

Why it happens: Sudden knocks or pops at the start of a cycle usually come from water hammer when the inlet valve opens. This may be caused by high water pressure, unsecured hoses, or a failing valve.

How to check: Inspect the water supply line, confirm that hoses are properly fastened, and test water pressure at the supply valve. If you notice vibration in the line when filling, it may be a water hammer issue.

When to call a technician: Persistent knocking during fill cycles suggests the inlet valve or water supply system requires adjustment or replacement by a professional.

Professional Help and Prevention

While small noises from loose dishes or minor debris can be solved at home, continuous loud sounds often point to failing mechanical parts. Circulation pumps, drain pumps, inlet valves, and chopper assemblies are precision components that require tools and experience to repair. Addressing the problem quickly prevents damage to other parts and avoids higher repair costs in the future.

Conclusion

Different noises from your dishwasher are more than just an annoyance. They provide valuable clues about hidden problems. Simple steps such as rearranging dishes or cleaning the filter can solve minor issues, but loud persistent sounds usually signal pump or motor faults. If you hear grinding, squealing, or repeated banging after basic checks, schedule service with a qualified technician to restore quiet and efficient operation of your dishwasher.