Commercial dishwashers are key kitchen appliances in the hospitality industry. They are designed to clean and dry several batches of dishes at the same time throughout the business day. Normally, commercial dishwashers make a humming noise while functioning. However, if it is loud, it means there is something wrong. Plus, your commercial dishwasher can also make some other noises that you should be aware of. Any noise that is louder or stranger, you should investigate it yourself or hire a commercial appliances repair technician to inspect the dishwasher.

Check The Ventilation Fan And Wash The Pump Motor

If your commercial dishwasher is making a humming noise, there could be two reasons i.e. the ventilation fan or a malfunctioning wash pump motor. Keep in mind that a commercial dishwasher does produce a slight humming sound when it is operating normally.

You should not confuse that with a problem. If the humming sound gradually becomes louder, then you should check these parts for problems. If you observe that your commercial dishwasher is making a loud humming noise during the drying cycle, it most likely means there is a problem with the ventilation fan.

The fan runs on a motor that consists of bearings. The bearings could be worn or the motor itself needs replacement. You can either try replacing the bearings or the motor to see if the problem gets fixed. During checking the bearings and the motor, check the fan blades as well. If the commercial dishwasher happens to be old, there are chances the fan blades are damaged, cracked, etc.

Furthermore, if your commercial dishwasher is making a high-pitched humming sound, it means the motor is faulty. The good news is that you might be able to replace it on your own if you have the right tools and skills. If not, you will be needing an expert.

Dishwasher Making Grinding Noise

Some commercial dishwashers make a grinding noise too when functioning, which is normal. This is usually the case in dishwashers with a motor-driven electronic control panel but the grinding should not be too loud. If the dishwasher has suddenly started making a loud grinding noise, you should check for a foreign object stuck inside.

Normally, a dishwasher makes a grinding noise when a foreign object is stuck between the blades of the dishwasher. This can happen during cleaning if a hardened food or a broken part of a dish fall to the bottom of the dishwasher. The object can stop the blades from rotating.

Therefore, if you hear your dishwasher producing a grinding or vibrating sound anywhere during the washing and drying cycle, turn it off and let the steam dissipate. Then, simply gain access to the bottom rack and remove it to inspect for any food items, glass, or dish parts.

Moreover, you will also need to inspect the dishwasher screen. It is present under the lower spray arm. Check for debris and remove it using water and soap. Next, move on to the pump housing cap and again check for debris. You will need to check every component visible and accessible for anything stuck.

Food items getting stuck is common in commercial garbage disposals too. Use the services of a commercial garbage disposal repair Alexandria technician for inspections.

Insufficient Water Spraying Into The Dishwasher

A commercial dishwasher requires a specific level of water to wash the dishes. If the water being sprayed in the dishwasher is insufficient, the machine might produce a weird grinding noise. For this, you will need to check the inlet valve for any clogs or issues that might be preventing the water from accessing the machine.

Circulation Pump Issue

The circulation pump as the term suggests helps circulate the water inside the machine. This pump also consists of bearings that might produce a grinding noise if they are worn. However, if the dishwasher is years old, it might be time to replace the motor. Make sure that you opt for the exact replacement or replace the dishwasher if it is frequently running into problems.

Dishwasher Making Banging Or Knocking Noise

If your dishwasher is making thumping noises, it most likely means that you have installed it too close to the walls or the cabinet, which is causing the drain line to vibrate against the walls. Adjusting the position of the dishwasher might solve the issue.

In addition to that, it could also be that the spray arm is hitting something inside the machine as it rotates. To fix the issue, you will need to access the dishwasher and check the spray arm for its mobility. If it’s having difficulty, it means either something is stuck or the spray arm itself needs replacing.

Dishwasher Making Noise When Draining

You might face a situation where your commercial dishwasher is making noise when draining. It might produce a loud rubbing, grinding, or humming sound. The likely cause could be the following.

Seized Drain Pump Issue

The drain pump is designed to drain the water out of the machine once the washing and drying cycle is complete. It is common for foreign objects to become stuck in the drain pump which will produce weird sounds as a result, especially during the drain cycle.

That said, you will need to check around and inside the drain pump to make sure nothing is hindering its performance. Clean the dishwasher first because it may stop the noises. If the noise stays after cleaning the unit, check and replace the drain pump.

Rattling Noises

When a dishwasher is running, you might hear rattling sounds due to loose forks or dishes contacting each other but that should neither be too loud nor continuous. Plus, rattling or squealing noise is also common in brand-new dishwashers if they haven’t been used in a long time.

Try running the machine using water for a while to check if the rattling noises goes away. If it doesn’t, it means there is a fault with the wash motor. To inspect the motor, you will need to run an empty cycle. It could also be due to a blocked filter, clogged drain, etc.

Do Commercial Dishwashers Require Maintenance?

Because commercial dishwashers work throughout the business week without any breaks, it is important to look after them and schedule expert maintenance to ensure everything works fine. At the same time, part of the responsibility also lies on the owner to train their employees to regularly inspect and clean the machine after a tough working day.

Commercial dishwashers require maintenance as other household appliances do. In fact, manufacturers also recommend scheduling expert maintenance to prevent costly repairs. The services can be expensive but will keep your machine running effortlessly for years to come.

In addition to that, it would be smart to maintain a maintenance log. That way, you will be able to keep track of the repairs and replacements without having to rely on your employees every time.


Summing it up, commercial dishwashers are tough and rigid machines but require care and maintenance. These machines might unexpectedly produce certain noises and you need to be prepared for that. So, keep the tips mentioned above in mind to quickly overcome the issue if you encounter a similar issue in the future. Take help from a professional for proper commercial dishwasher repairs Northern VA.

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