Grinding Metal Noise From Garbage Disposal? (Possible Causes & Fixes)
Normally, the only sound that you hear from your garbage disposal is food being pulverized. The sound of grinding metal tells you that something is wrong. Fortunately, you can fix the problem.
Troubleshoot a grinding metal noise from your garbage disposal. It may be a small metal kitchen tool. One of the blades may be broken, or the flywheel may have some damage or corrosion. Check for foreign objects first. If the chamber is clear, use a flashlight to inspect the flywheel and blades.
There are several problems that cause grinding metal noises to come from a garbage disposal. Here are the most common ones, and how to fix them.
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1. Small Metal Object
A common reason for a grinding noise from a disposal is a small metal object rattling around inside the chamber. Kitchen sink drains are ideal places to lose jewelry, measuring spoons, and other items. Remove the foreign object to prevent damage to the flywheel and blades.
How to Fix the Problem
The drain of your kitchen sink is covered with a rubber baffle. Pull the baffle up to see into the chamber. Do not remove the baffle. Shine a flashlight into the chamber, and look for any obvious metal objects. Move the flashlight around to inspect every part of the chamber. Small metal objects get trapped under the blades, between the flywheel and wall of the chamber, and between the blades. If you find an item in the chamber, use tongs or needle nose pliers to remove it.
If you don’t see any objects inside the chamber, remove the disposal. Open the chamber, and remove any pieces of metal that you find.
2. Damaged Blades
The blades of a garbage disposal are fairly durable, but they can be damaged by hard objects that are put inside the chamber. The rivets on the blades can come loose. Both of these situations will cause a grinding metal sound.
How to Fix the Problem
Damaged garbage disposal blades need to be replaced. The food waste will not be pulverized properly, and this can clog the disposal and plumbing pipes. You can have the blades replaced, but the repair costs the same as a new garbage disposal. It is best to replace the unit.
3. Broken Flywheel
The flywheel of a garbage disposal is a round metal disc at the bottom of the chamber. The blades are attached to the flywheel with rivets. A broken flywheel rattles when you run the disposal because it is not secured in place. A loose flywheel will also cause the blades to move around and come loose.
How to Fix the Problem
Replace the grinding unit of the disposal. This is a fairly intensive DIY job, so you may want to have a plumber fix the problem. The cost of the repair may be the same or more than a new unit. Consider replacing the garbage disposal if the flywheel is damaged.
4. Corrosion
Garbage disposals are designed to last for about ten years. The metal parts should withstand the constant exposure to water, but sometimes parts fail prematurely. Certain types of foods break down the metals. When you have corrosion inside a garbage disposal, small metal parts rub together and make a grinding noise.
How to Fix the Problem
Corrosion on the metal parts of a garbage disposal cannot be repaired. Even if you replace the affected parts, it’s only a matter of time before more parts fail. Replace the entire unit.
5. Hard Objects
Seeds, small rocks, bones, and other hard objects jam the blades of a garbage disposal. The blades may be able to spin, but the object grinds against the flywheel as the blades turn. Removing the hard object from the blades fixes the problem.
How to Fix the Problem
You will need a flashlight, long wooden spoon, and tongs for this job. Lift the baffle of the drain, and shine the flashlight into the chamber. Look for a small object that is jammed under one of the blades. Put the handle end of the wooden spoon against the blade, and apply gentle pressure. You may need to press down on the flywheel. Dislodge the object from the blade, and remove it from the chamber with tongs or needle-nose pliers.
If you cannot move the blades with a wooden spoon, use an Allen wrench to manually turn the flywheel. Insert the wrench in the hex bolt on the underside of the disposal chamber. Move the wrench back and forth until it moves freely. Check the inside of the chamber to see if you can see any loose objects.
6. Vibration
Distinguishing between the various sounds of metal rubbing together can be challenging, even for professional plumbers. You might be hearing a metal sound from another source, such as the silverware in the drawer next to the kitchen sink or small objects on the countertop. You can test for vibration from your garbage disposal buy turning it on and touching the countertop. If you feel a vibration, the problem is with the connections on the disposal.
How to Fix the Problem
Remove all the items from the cabinet under the kitchen sink. Use a flashlight and screwdriver to inspect the plumbing connections and bolts on the disposal. Tighten loose bolts, and replace missing bolts. Check the metal bands around plumbing pipes.
Other Unusual Noises from a Garbage Disposal
Your garbage disposal may make other unusual noises from time to time. Here are some noises that you may hear, and how to fix them.
Squealing, Whining, and Screeching
If your garbage disposal squeals and whines, the motor is bad. You can verify this by checking for a burning smell inside the cabinet. Replacing the motor is not cost-effective. You will spend just as much on a new garbage disposal.
Thumping
A thumping sound from your garbage disposal is caused by food waste or loose bolts. Foods that are hard or shred easily get stuck to one side of the disposal. This causes an imbalance that causes the unit to shudder. Remove the food waste with tongs. Check the bolts that attach the garbage disposal to the sink drain and plumbing pipes.
Humming
A humming garbage disposal that doesn’t grind food is overheated. A safety switch on the unit disengages the flywheel and blades so the motor can cool down. Place your hand on the side of the chamber under the sink. If it feels warm or hot, wait about 10 to 15 minutes. Once the chamber is cool, reset the red button on the underside of the disposal. It should be located on the opposite side of the plumbing drain pipe along the edge of the chamber. If the button does not reset, let the disposal cool down a bit longer.
Related Questions
Should I ignore a grinding metal sound from my garbage disposal?
No, you should find the problem, and fix it. The most common reason for a grinding metal noise is a small object trapped inside the chamber. Removing the object fixes the problem and prevents any damage to the blades and flywheel.
Should I replace my garbage disposal if it’s making noises?
If your garbage disposal is making noises every time you use it, replacing it is a good option. You may spend less on a new garbage disposal than frequent repairs to keep an old disposal running.
How do I know if my garbage disposal needs to be replaced?
There are many signs of a garbage disposal that is at the end of its lifetime. Strange noises are one of the most obvious. An aged garbage disposal will overheat, clog, leak, and not pulverize food waste. Plumbing pipe clogs also mean that it may be time to replace the garbage disposal.
How can I prevent objects from falling into my garbage disposal?
Exercise caution when you are working at your kitchen sink. Remove your jewelry, including rings, bracelets, and necklaces. If you are doing repairs near the kitchen sink. Put screws, bolts, nuts, and other small items in a bowl next to the sink. Buy a screen to cover the drain.
Do I need to oil the blades of my garbage disposal?
Garbage disposals do not require oil for lubricating the parts. Water is the best way to lubricate the moving parts inside the chamber.
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What Did We Learn?
The sound of grinding metal from your garbage disposal can mean many things. A small metal object may have fallen into the chamber, or there may be a hard piece of food trapped in the blades. Grinding noises can also be related to vibration, corrosion, broken flywheels, and damaged blades. You can fix the problem by removing foreign objects, replacing broken parts, and securing the disposal. In some cases, the disposal should be replaced.
There are steps that you can take to prevent grinding metal noises from your garbage disposal. Take extra precautions when you are doing repairs in the kitchen. Remove all jewelry when you are doing the dishes. Put a screen over the drain to catch any small items that are in the sink.
Jennifer L. Eggerton loves being hands-on, whether it's with a home DIY project, making repairs, re-decorating a room, or keeping life organized. She enjoys helping people by sharing her knowledge, insights, and experiences, as well as her lessons learned. In addition to her work as a writer, Jennifer is a Jeep® overlander, self-published author, and nature photographer who loves being outdoors.
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