Dishwasher Making a Thumping Noise (Troubleshooting Guide)

On this page

Quick answer
Confirm the symptom
Tools and prep
Step-by-step troubleshooting
Common causes table
Parts matching
When to call a pro
FAQ
Related guides

Quick answer

A thumping noise in your dishwasher is often caused by loose items or a faulty pump. Turn off the power, check for loose dishes or debris, and inspect the pump and drain hose for issues.

Confirm the symptom

Hearing a rhythmic thumping or knocking sound during operation
Noise occurs during the wash or drain cycle
Sound is not constant but happens periodically

Tools and prep

Screwdriver set
Flashlight
Work gloves
Plumber's putty (if resealing hoses)
Turn off the dishwasher's power at the circuit breaker
Shut off the water supply to the dishwasher

Step-by-step troubleshooting

Check for Loose Items
Do: Open the dishwasher and look for loose dishes, utensils, or debris inside the tub.
Observe: Loose items may vibrate or thump against the sides during the cycle.
Means: Remove any loose items and ensure racks are properly positioned.
Next: If the noise persists, move to the next step.
Inspect the Pump and Drain Hose
Do: Locate the pump and drain hose (usually at the bottom of the dishwasher) and check for obstructions or damage.
Observe: A clogged or damaged pump or hose can cause thumping during the drain cycle.
Means: Clean out any debris and inspect for cracks or leaks.
Next: If the pump or hose is damaged, replace the part.
Check the Water Inlet Valve
Do: Inspect the water inlet valve for mineral buildup or damage.
Observe: A faulty valve can cause water flow issues, leading to unusual noises.
Means: Clean the valve with vinegar or replace it if damaged.
Next: If the noise continues, check the motor.
Test the Motor and Motor Mounts
Do: Listen for the motor during operation and check the motor mounts for looseness or wear.
Observe: A loose or worn motor mount can cause the motor to vibrate and thump.
Means: Tighten or replace the motor mounts as needed.
Next: If the motor is faulty, professional repair may be needed.
Examine the Dishwasher Feet
Do: Check the dishwasher's leveling feet for stability and proper contact with the floor.
Means: Adjust or replace the feet to ensure the unit is level and stable.
Next: If the unit is level and stable but noise remains, contact a professional.
Run a Diagnostic Cycle
Do: Refer to the user manual to run a diagnostic cycle, if available.
Observe: The diagnostic may identify specific error codes or issues.
Means: Follow the manual's guidance for resolving the issue.
Next: If the diagnostic doesn't resolve the issue, contact a professional.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Loose dishes or debris Items can vibrate or thump against the sides during the wash cycle.	Common	Easy	None
Clogged or damaged pump A blocked or faulty pump can cause thumping during the drain cycle.	Common	Medium	Pump assembly
Faulty water inlet valve Mineral buildup or damage can disrupt water flow, causing noise.	Sometimes	Easy–Medium	Water inlet valve
Worn motor mounts Loose or worn mounts can cause the motor to vibrate and thump.	Sometimes	Medium	Motor mounts
Unstable dishwasher feet Improper leveling can lead to vibrations and thumping sounds.	Sometimes	Easy	Leveling feet
Faulty motor A damaged motor can produce unusual noises during operation.	Rare	Hard	Motor assembly

Parts matching

Common parts that may need replacement for a thumping dishwasher include:

Pump assembly
Water inlet valve
Motor mounts
Leveling feet
Motor assembly

Use your dishwasher's model number to find the correct replacement parts at a home improvement store or online retailer.

When to call a professional

The noise persists after checking all loose items and cleaning the pump
You identify a faulty motor or damaged pump that requires professional replacement
The dishwasher is not level and adjusting the feet doesn't resolve the issue
You're unsure about diagnosing or replacing internal components like the motor or valve

FAQ

Why does my dishwasher make a thumping noise during the drain cycle?

A thumping noise during the drain cycle is often caused by a clogged or damaged pump. Check the pump and drain hose for obstructions or wear.

Can loose dishes cause a thumping sound in my dishwasher?

Yes, loose dishes or utensils can vibrate or thump against the sides during the wash cycle. Always ensure dishes are properly loaded.

How do I know if the motor mounts are worn out?

If the motor is vibrating or making a thumping noise, the motor mounts may be loose or worn. Inspect them for damage or wear.

Is it normal for a dishwasher to make some noise during operation?

Some noise is normal, but a rhythmic thumping or knocking sound is not. Investigate the source to prevent further damage.

Can I fix a thumping noise in my dishwasher myself?

Yes, in many cases you can resolve the issue by checking for loose items, cleaning the pump, or adjusting the feet. For internal components like the motor or valve, professional help may be needed.