Why is Your Dishwasher Making That Sound?

Dishwashers are not the quietest appliance in the world. Even modern, high-end dishwashers make the occasional click and splashing sound. Dishwashers are designed to throw water around at high velocity in order to wash dishes without the need of a hand to scrub them. Water is heated, cycled, mixed with soap, and cycled again, It is projected through spinning sprayer arms and telescoping nozzles. A dishwasher functioning perfectly will make a few sounds in each washing cycle.

However, a dishwasher that is malfunctioning is even noisier than usual. This is why it’s so helpful to understand the sounds your dishwasher makes and what that might mean for your maintenance tasks ahead. Let’s explore the many sounds your dishwasher might make and why those sounds are happening.   

Shaking Against the Cabinet

Most large appliances have the potential to rattle, shake, or bang based on the movement of the whole unit. When the outside panels of the dishwasher shake against the inner cabinet walls of your kitchen, a banging or repeated thumping sound will occur. Just like your washer or dryer might shake against the wall, your dishwasher can shake against the inside of the cabinetry.

The most common cause for shaking is uneven feet. A dishwasher properly installed will not shake because the feet will sit flat on the ground. But if the ground is uneven or if one foot is too long or short, the entire unit will wobble and knock nearby surfaces. 

Rattling Sprayer Arms

The main washing power in your dishwasher comes from the sprayer arms. These spinning arms are lined with a few dozen holes that spray water at high velocity over the dishes. The arms spin fast and contain a lot of water pressure. If you’ve ever poked your sprayer arms between washes, you may hear that they rattle a little in place. So it should come as no surprise that a certain amount of rattling might be heard when the sprayer arms spins during the cycle.

If you hear a faint rattling sound inside the dishwasher, don’t worry. A louder rattling, however, can indicate that your sprayer arm or a similar moving part has come loose and is no longer functioning smoothly as it should. This could be something slipped out of place or a small plastic securing tab has broken and a piece may need to be replaced. 

Splashing Water

The most common sound to hear from the dishwasher is the splish, splash, and swishing sound of water. The dishwasher throws a lot of water around. That water sprays at high speeds and splashes against every dish in the dishwasher. It splashes against the inner walls of the dishwasher, runs down to the bottom, and is pumped back through the sprayers again with soap mixed in, then rinsed away.

Don’t worry about water sounds unless you see signs of a leak or suspect that your sprayer mechanisms are broken. 

Clicking Cycle Timer

Dishwashers also make a clicking sound quite frequently. most dishwashers cycle using a gear mechanism, often seen in a turning dial for the controls. This gear cycles to tell the dishwasher when to spray water, when to heat, when to release the soap, and when to drain. When your dishwasher switches to the next phase, you may hear clicking or even something that sounds like mechanical clunking.

When the dishwasher is going through a cycle, you might also hear light clicking or a ratcheting sound as the gear spins to the next change-over point. 

Snapping Soap Cup

There are several types of soap-cup enclosures for the models of dishwasher. Some are turn-to-close, some have a press-button latch. Many have a spring-loaded lid that pops open to release the soap partway through the dishwasher washing cycle. If you have heard an alarming snap or bang halfway through your dishwasher’s cycle, don’t worry. As long as this sound only happens once per cycle and there’s nothing broken when you check, that means it’s the soap cup opening.

When the latch on the soap cup is released, it springs open and the back of the lid hits the dishwasher door. Because the dishwasher door is mostly hollow (made of two panels fit together), this sound is unusually amplified. Especially when the dishwasher door is closed.  

Revving Pump Motor

A revving sound can also range from normal to worrying, depending on the volume and nature of the revving. A dishwasher has one or two pumps. One pump drains the bottom and one pump provides the pressure necessary for the sprayer arms. Both pumps are run by motors, and motors have a tendency to hum and rev. If a motor picks up, pumping harder than it was a moment ago, then you may hear a revving sound.

If that rev sounds ragged or unusually loud, this may be a sign that your pump motor is on the way out or needs maintenance. 

Grinding Garbage Disposal

Some dishwashers are designed with their own garbage disposal. Underneath the dishwasher drain is a set of spinning blades designed to break up any food pieces and break up congealed substances that come off the dishes. Just like the garbage disposal in your sink, those spinning blades make a grinding sound. You may already know the difference by-ear between a clean grinding disposal and one that’s got something caught between the blades.

For dishwashers without a garbage disposal, that grinding sound might be a sign that one of the motors or the spinning sprayer arms may not be functioning properly. 

Hidden Banging Pipes

The dishwasher’s water valve incudes a hammer which can suddenly stop the flow of water. This also suddenly increases the amount of water pressure in nearby pipes. The occasional unexpected bang sound is sometimes the sound of your pipes promptly swelling and knocking against each other or the wall.  

Squealing Water Lines

The last weird sound you might hear from your dishwasher is a squealing sound. This is actually very normal for any pipes that are not –at that moment– full of water when they are turned on. A dishwasher that has recently been installed may make a squealing sound the first time you run it. This is OK and a normal part of the dishwasher’s startup process.

The same is true of dishwashers that have been unused for a month or more. If the water has drained and must refill the water lines, you may hear some squealing.