River City PlumbingFounded by Tony Harris

Garbage disposal humming but not spinning? Try this first

By River City Plumbing 4 min read

A disposal that hums but won’t spin is almost always jammed. The motor is getting power, but something’s wedged inside and the plate can’t turn. Turn it off, cut the power, and use a 1/4 inch Allen wrench in the socket on the bottom of the unit to work it loose. Then pull out whatever jammed it, press the reset button, and try it again with the water running.

Never put your hand in a disposal. Not even with the switch off. Someone can flip the wall switch without thinking. Use tongs or needle-nose pliers, and cut the power before you reach for anything.

How to unjam a garbage disposal

  1. Turn it off at the wall switch right away. Don’t let it sit there humming. That’s how motors burn out.
  2. Cut the power. If it plugs in under the sink, unplug it. If it’s wired directly, turn off its breaker.
  3. Look at the very bottom of the disposal. Most have a small hex-shaped socket dead center. It takes a 1/4 inch Allen wrench, and a lot of disposals came with a little one made for it. Check under the sink or in the junk drawer before you go buy one.
  4. Put the wrench in and work it back and forth. It’ll be stiff at first. Keep rocking it until it turns all the way around.
  5. Shine a flashlight down the drain opening and fish out whatever caused the jam with tongs or pliers. It’s usually a fruit pit, a chunk of bone, a bottle cap, or a spoon.
  6. Find the reset button on the bottom of the unit. It’s usually red. Press it until it clicks. If it won’t stay in, give the motor 10 minutes to cool and try again.
  7. Turn the power back on, run cold water, and flip the switch.

If it still hums after all that, either something’s still in there or the motor is on its way out.

What if it doesn’t hum at all?

Silence means no power is reaching the motor. Check these in order:

  1. The reset button. A jam or an overload trips it, and it’s the most common reason a disposal goes dead.
  2. The breaker panel. Look for a tripped breaker for the kitchen or the disposal.
  3. A GFCI outlet. If the disposal plugs in, that outlet might be a GFCI, or it might be protected by one somewhere else in the kitchen. Press the reset button on any nearby.
  4. The wall switch. They wear out like anything else.

If none of that brings it back, the problem is in the wiring or the motor. We can tell you if it needs a new disposal or an electrician.

Where is it leaking from?

Dry the outside of the disposal with a towel, run some water with the disposal off, and watch with a flashlight. Where the water shows up tells you most of the story.

  • The top, where the disposal meets the sink. That’s the sink flange. The putty seal has dried out or the mounting has worked loose. It can usually be taken apart and resealed.
  • The side, at a connection. Either the dishwasher hose or the pipe that runs from the disposal to the trap. Tightening the hose clamp or replacing the gasket on the drain connection usually fixes it.
  • The bottom or the body of the unit. That means an internal seal has failed or the housing has rusted through. There’s no fixing that, so it’s time for a new disposal.

What shouldn’t go down a disposal?

A disposal is built for small, soft scraps that get past your plate scraper. It’s a bad trash can. Keep these out:

  • Grease, oil, and fat. They coat the pipes and harden further down the line.
  • Stringy stuff like celery, corn husks, and onion skins. The fibers wrap around the parts.
  • Potato peels. They turn into a paste that plugs the drain.
  • Pasta and rice. They keep swelling after they go down.
  • Coffee grounds. They settle in the trap like wet sand.
  • Eggshells. People argue about these. We’d just throw them away.

Run cold water the whole time it’s grinding and for a few seconds after. Cold water keeps any grease that sneaks in solid, so it gets chopped up and carried off instead of coating the pipe. If the sink is already draining slow, here’s what’s worth trying on a slow drain.

When should you replace it instead?

Disposals don’t last forever, and one that’s been under your sink for a decade doesn’t owe you much. It’s time for a new one if:

  • It leaks from the bottom or the body
  • It jams constantly, even when you’re careful with it
  • It hums with nothing jammed, which usually means the motor is dying
  • The reset button keeps tripping no matter what you do
  • It’s gotten loud in a new way, or noticeably weaker

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