Dishwasher Making Clunking Noise: Causes & Fixes

Quick Answer

The most common clunking noise is the spray arm or rack physically hitting dishes, a loose utensil, or the tub wall after the rack shifts. It happens when tall items, poorly secured racks, or worn rack hardware let parts move into the spray arm’s path. First diagnostic action: stop the cycle, spin both spray arms by hand, and slide both racks in/out to confirm nothing contacts or rocks.

Identify the Noise First

During water fill: If the clunk happens while the tub is still dry or just starting to wet, it’s usually a loose rack, wheel, or item shifting as the machine vibrates at startup. Pause, then push/pull each rack; listen for the same clunk.

During spray / circulation: A repeating clunk every few seconds usually tracks spray arm rotation hitting something. Open the door mid-noise (it will stop immediately), then close it and see if the clunk resumes right away. That start/stop behavior points to moving internal parts contacting each other.

During draining: If the clunk happens mainly at the drain portion and not during wash, it’s less likely to be a spray arm strike and more likely load/rack movement from vibration. Confirm by running a short rinse with the racks empty; if the clunk disappears, load shift is the trigger.

During heating: A single knock as the unit heats can be racks or a large pan shifting slightly as hot water and steam change tension. If it’s a one-time tick/clunk and not rhythmic, focus on rack stability and protruding items, not pumps.

At start of cycle: A clunk right after the door locks is commonly the upper rack settling onto misaligned rails or a wheel dropping into a worn spot. Pull the rack out fully and re-seat it on the rails.

At end of cycle: A clunk as the cycle ends is often dishes relaxing as cooling begins or a light load shifting when the final water movement stops. Check for top-heavy items that can tip when the spray stops.

Constant: A steady, repeating clunk is almost always a rotating part striking a fixed object (spray arm to dish, spray arm to rack, rack to tub). Stop and check for contact points.

Intermittent: Random clunks are usually an item flipping, a utensil migrating through the basket, or a rack wheel momentarily binding then releasing. Your goal is to reproduce it by gently rocking the racks and spinning arms by hand.

What This Noise Usually Means

A clunk is impact: something inside the tub is moving into something else. In dishwashers, the two movers are the racks (sliding and vibrating) and the spray arms (rotating under water pressure). When a rack sags, a wheel jumps, a stop clip is missing, or a tall item protrudes, the spray arm’s tip or hub can strike that obstruction and make a rhythmic clunk. Alternatively, a loose item can shift and hit the door, rack frame, or tub wall as the machine vibrates.

Most Common Causes

Tall dish or utensil blocking a spray arm: Baking sheets, cutting boards, long spatulas, or wine glass stems can extend into the spray arm sweep and get hit repeatedly.
Upper rack not fully seated on the rails: If one side is slightly off, the rack sits crooked and can droop into the spray arm path or contact the tub when the unit vibrates.
Worn or broken rack wheels/rollers: Flat-spotted wheels, cracked hubs, or missing rollers let the rack drop and shift, increasing the chance of intermittent contact.
Loose rack stops or end caps: Missing/broken stops allow the rack to slide farther than intended, causing the rack frame to hit the door or allowing heavier loads to shift suddenly.
Spray arm hitting the rack due to sagging rack tines or frame: Bent tines or a slightly twisted rack frame can lower the load area into the arm’s rotation zone.
Light plastic items flipping or migrating: Lids and lightweight containers can move during wash and get struck, producing occasional clunks rather than a steady rhythm.

How to Check Safely

1) Confirm cycle stage

Run a rinse cycle and listen. If the clunk is rhythmic and begins once spraying starts, prioritize spray arm contact checks. If it happens during startup vibration or transitions, prioritize rack alignment and loose hardware.

2) Isolate the load factor

Stop the cycle, open the door, and remove loose or tall items first (utensils sticking up, boards, large pans). Restart for 1–2 minutes. If the clunk stops, you’ve confirmed load interference rather than a fixed internal defect.

3) Inspect relevant components

With power off at the controls (and the door open), spin the lower spray arm by hand. It must rotate freely without touching dishes, the rack, or the tub. Repeat for the upper spray arm or upper spray arm assembly. Then slide each rack fully out and in; it should track smoothly with no drop, tilt, or knock at the ends.

4) Confirm or rule out obstruction

Look for scrape marks: fresh scuffing on spray arm tips, shiny rub spots on rack wires, or chipped coating where contact occurs. Check the utensil basket for long items that can poke through. Ensure no item protrudes below the upper rack where it can intercept the lower arm.

5) Perform a controlled test

Run the dishwasher empty (racks installed, nothing loaded). If the clunk is gone empty but returns when loaded, it’s a loading/rack shift issue. If it still clunks empty, focus on rack hardware and spray arm clearance: verify both racks are level, wheels intact, stops present, and spray arms firmly mounted and not wobbling into the rack.

When This Is Normal vs A Problem

Usually normal: A single clunk when you first start the cycle as the racks settle, or an occasional light knock from a plastic lid shifting—especially if it only happens with certain loads and stops when you re-load correctly.

Problem: A repeated clunk that matches spray arm rotation, any clunk that leaves scrape marks on the spray arm or racks, or clunking that happens every cycle regardless of load. Also treat it as a problem if the rack feels loose, drops when pulled out, or the spray arm cannot be spun freely by hand.

When to Call a Technician

Call for service if the clunk continues with the dishwasher empty, if rack rails are bent and the rack won’t track straight, or if you see damage that affects safety or wash performance (cracked spray arm, broken rack supports, sharp rack wire ends). Also call if the spray arm mounting is loose or wobbles and tightening or reseating it doesn’t restore stable clearance.

How to Prevent This Problem

Keep tall items to the sides and verify spray arm clearance by spinning the arm before starting.
Load utensils handle-down (where appropriate) and keep long tools from sticking above the basket rim.
Replace worn rack wheels/rollers before the rack begins to sag or bind.
Confirm rack stops/end caps are present on both sides so the rack can’t over-travel and slam.
Avoid top-heavy loading that lets items tip when water pressure changes.

Conclusion

A clunking dishwasher is usually internal contact: the rack or load shifts and the spray arm or rack frame hits something it shouldn’t. Identify whether it’s rhythmic during spraying, then verify spray arm clearance and rack stability. If it stops when you change the load, fix the loading and worn rack hardware. If it clunks empty, inspect racks, stops, and spray arm mounting for looseness or misalignment.

Frequently Asked Questions

Why does the clunking stop when I open the door?

Opening the door stops spraying and immediately reduces internal movement. If the clunk stops instantly and resumes as soon as you close the door, that strongly indicates a moving internal part (usually a spray arm) was striking a dish, rack wire, or a loose item during rotation.

How can I tell if it’s the lower or upper spray arm hitting something?

Remove the lower rack and spin the lower arm by hand; then reinstall the rack and repeat. Do the same with the upper rack and upper arm. The arm that can’t complete a full rotation without touching something is the one making the clunk. Also, low clunks usually trace to the lower arm and base of the tub; higher, sharper knocks often trace to the upper rack area.

My rack feels wobbly. Can that alone cause a clunk?

Yes. A rack that tilts or drops changes the clearance between the rack/load and the spray arm path. Even if nothing is obviously blocking the arm at rest, vibration and water force can shift the rack just enough for intermittent impacts. Worn wheels, missing rollers, and a rack not seated evenly are common triggers.

What marks should I look for to confirm impact inside the tub?

Check spray arm tips for fresh scuffs, whitening, or worn plastic. Look for rubbed-through rack coating or shiny metal spots on rack wires. Also check the inside of the door and the tub sides for new rub marks where a rack corner or protruding utensil could be striking.

Can overloading cause a clunk even if the spray arms spin by hand?

Yes. Hand-spinning checks static clearance, but water pressure can lift lightweight items, shift tall pans, or move utensils in the basket. If it clunks only when fully loaded, reduce height at the center, keep large flat items on the edges, and secure light plastics so they can’t float into the spray arm path.

There’s a quiet relief in letting this settle into the background, where it belongs. The noise fades, and what’s left feels less like a chore and more like normal life again.

Not everything has to be dramatic to matter. With the heavy part already handled, the days can move on—still imperfect, but finally easier.