A garbage disposal is one of the handiest appliances to have in the kitchen. It makes cleaning up after meals much easier by grinding up and washing away small bits of leftover food. However, like most appliances, garbage disposals can develop issues over time. One of the most common problems is a garbage disposal that is suddenly very loud or making strange noises.
An overly noisy garbage disposal is not only annoying but can indicate a deeper problem. Identifying the specific sound and cause of the noise is the first step to fixing the issue. Most garbage disposal noises point to one of the following underlying problems:
Obstructed Shredder Plates
The shredder plate is located in the grinding chamber of the disposal unit. This is the part responsible for pulverizing the waste as the water flushes it down the drain. Over time, small fibers from food items like fruits and vegetables can get lodged and build up on the sharp edges of the shredder plate. Common culprits include:
- Potato peels
- Corn husks
- Celery fibers
- Onion skins
- Greens like lettuce or spinach
- Fruit skins and pits like lemons or avocados
When debris builds up, it can prevent the shredder plate from spinning properly. The disruption in motion causes the disposal blades to slow down significantly, resulting in straining motor noise. It may sound like a loud, repetitive grinding or rattling metal, depending on the exact placement of the stuck debris.
To Fix Obstructed Shredder Plates:
- Turn off power to disposal at circuit breaker – Safety first! Make sure disposal is completely disconnected from power source before doing any sort of maintenance.
- Check for and remove obstruction – Carefully examine the inside of the disposal grinding chamber. Often you can spot fibers caught on the shredder plate teeth. Use long-handled tongs to pull out any visible debris.
- Run disposal to test – Turn breaker back on, turn on cold water, and briefly start disposal to see if noise continues. If noise returns or you can’t spot a clog, may need to do full shredder plate maintenance.
- Remove and clean plate – Unscrew plate using a wrench and thoroughly scrape and rinse under water to remove all gunk buildup.
- Replace shredder plate – Reattach plate, securely tightening all screws. Run disposal for 30 seconds with water on to check if noise is resolved.
Loose Mounting Parts
The grinding components of garbage disposal, like impellers, shredder plates, and drive shafts, are all separately mounted within the main unit chamber. These interlocking parts need to remain tightly affixed in order to prevent vibrations as the motor rapidly spins them.
Over years of daily use, the grinding parts can loosen slightly until gaps form between the mounts. When spinning at high speeds, the loose pieces start to rattle and knock around, creating loud clanging, grinding, or rattling noises.
To Fix Loose Mounting Parts:
- Turn off power to disposal – Always cut electrical supply before putting your hands inside the unit!
- Inspect mounts – Remove rubber splash guard to get visual on all mounting sites. Check for loose bolt heads or visible gaps between parts and body.
- Tighten mounts – Use a wrench to tighten any loose screw mounts throughout grinding assembly. Go slowly and do 1 turn at a time to realign parts.
- Check spin – Carefully use a wooden spoon to manually spin internal parts. Listen and feel for any remaining friction spots. Further, tighten mounts in problem areas.
- Test with power – Restore power, run water, and turn on disposal for short bursts. Listen for noise differences. Repeat spin method to check for further tightening needs.
Worn or Damaged Motor
The motor is the powerhouse that drives the mechanical shredding and grinding inside a disposal. An induction-type electric motor rapidly rotates a drive shaft connected to the shredder plate. With frequent use over many years, these motors eventually wear down.
The most common signs of a failing disposal motor include:
- Humming sound when turned on
- Buzzing noise without normal grinding
- Slowing down during use + loud squealing
- Getting stuck frequently while processing food
Once deterioration begins, the problems tend to worsen over time until the motor stops completely. Continuing to use the stressed motor can burn it out quicker.
To Address a Worn Out Motor:
- Determine extent of wear – Listen to noises made at start up versus mid-grinding. Notice if and when sounds change.
- Check spin freely – Unplug power and use wooden spoon handle to manually turn motor shaft. It should spin quickly and freely when pushed.
- Consider replacement – If motor struggles to run or spin, has loud/bad noises, gets stuck often, or shows other signs of decline, replacement may be necessary.
- Install new unit – While owners can replace just the motor, it usually makes more sense to install an entirely new garbage disposal. This ensures all parts are in good shape and under warranty.
Clogged Drain Lines
While not technically part of the garbage disposal unit, clogs in the drain line exiting the chamber can cause water to back up and prevent proper flushing of ground waste. When debris starts accumulating in the disposal without fully draining, it can significantly damper the motor and spinning shredder blades.
Signs of a slowing or overloaded disposal caused by drain clogs include:
- Loud humming noise
- Disposal struggling to grind fully
- Backed up water in the chamber
- Food particles visible through drain hole
To Address Clogged Drains:
- Plunge the drain – Use a sink plunger to force clogs down the line so water can start flowing freely again. Cover other openings first.
- Use baking soda/vinegar – Pour baking soda down drain, follow with heated vinegar – the chemical reaction can help dissolve blockages. Let sit 30 minutes then rinse with hot water.
- Manual removal – If plunging doesn’t work, you’ll likely have to open up the P-trap pipe underneath to pull out and clear debris manually.
In some cases, the clog may be further down the pipes and require a drain snake to fully clear. Once drainage is restored, run the disposal fully to flush the chamber and blades.
Bad Wall Switch
While not directly linked to the appliance itself, a faulty wall switch can mimic disposal problems. This switch is what allows power to flow to the unit when turned on. When this component fails, it can cause the disposal to randomly turn off, sputter, hum, cycle on and off, or not turn on at all – all of which seem like motor issues.
Warning signs of a bad wall switch include:
- No power at all to disposal
- Machine not starting with switch flipped
- Machine turning itself off while running
- Intermittent power causing sputtering noises
To Replace the Wall Switch:
- Turn off breaker – Ensure power is fully disconnected before doing any electrical work.
- Remove switch mounting screws – Take out existing switch panel from the wall.
- Disconnect wires – Detach the disposal wires from the back of the faulty switch.
- Install new switch – Connect new switch wires matching previous setup, mount into wall opening, then replace cover plate.
- Restore power and test – Turn breaker back on and flip disposal switch several times to verify proper operation.
Damaged Flywheel
The flywheel is a flat, rotating disc that sits at the bottom of the disposal chamber near the shredder plate. As food waste and water enter, the flywheel helps sling debris outward to the edges for grinding against the plate ridges. Over time, small rocks, glass, bones, silverware, and other foreign items can get caught near the flywheel. If spun forcefully into the flywheel fins, they can cause chips or cracks.
Typical sounds produced by a damaged flywheel include:
- Loud, repetitive banging as flywheel spins
- Scraping metal noise at regular intervals
- High pitched squealing or screeching
- Knocking noise despite no visible obstructions
To Repair a Damaged Flywheel:
- Remove power to disposal – Always disconnect from electricity before disassembly.
- Drain remaining water – Scoop out excess water in chamber with a small cup. Absorb remaining dampness with rags.
- Take out fasteners – Using a wrench, loosen the mounting bolts holding the flywheel in place until it can be lifted out.
- Inspect thoroughly – Check both sides of flywheel for cracks, missing chunks, heavy scratching, and other physical degradation.
- Replace if needed – If damage is beyond minor scratches, install a replacement flywheel. Make sure it aligns properly before re-tightening fasteners.
- Test operation – Run disposal briefly to listen for banging and other loud noises. Repeat spin tests on shredder plate and flywheel to check for friction.
Also Read: How To Repair a Garbage Disposal
How to Prevent Noisy Garbage Disposal Issues
While noise issues eventually crop up from regular wear-and-tear, there are ways to extend the quiet operation of your garbage disposal:
- Run plenty of cold water when grinding food waste
- Let water flush completely after each use
- Avoid putting certain items down the disposal like rice, pasta, eggshells, corn husks, etc which can get stuck
- Run ice cubes through disposal once a month help clean shredding components
- Every 3 months, replace ice cubes with 1⁄2 cup baking soda and 1⁄2 cup vinegar to deodorize and prevent waste buildup
- Don’t put bones, fruit pits, silverware, glass, rocks, shells, or other very hard or non-food items in disposal
- Listen for changes in sound over time and address new noises early before they intensify
Following these garbage disposal best practices will optimize performance and prolong the quiet operation of this indispensable kitchen appliance.