Garbage disposal hums but won’t grind: what is safe to try

A garbage disposal tells you a lot by the sound it makes when you flip the switch. A low hum with nothing turning is one problem. Dead silence is another. Water in the sink cabinet is a third, and it may have nothing to do with the motor at all. Some of these you can sort out yourself, safely, with the right tool and the power off. Others mean the unit is finished, or that the leak is somewhere I should be looking.

What the hum, the silence and the puddle mean

A hum means the motor is getting power and trying to turn, but the grinding plate inside is stuck. Usually something is wedged between the plate and the ring around it: a fruit pit, a bottle cap, a bit of bone, or a piece of glass that slipped off a counter. Silence means the motor is not getting power, either because the switch or breaker is off or because the unit’s own overload protection has tripped. A puddle under the sink is its own category. Water can come from the seal where the disposal meets the sink, the hose from the dishwasher, the pipe that carries waste out of the disposal, or the body of the unit itself. Each of those points to a different fix, and only one of them, a leaking body, means the disposal has to come out. Figure out which of the three you have before reaching for anything.

Power off before anything else

Whatever the symptom, the first step is the same: make sure the disposal cannot start. Turn the wall switch off. If the unit plugs into an outlet under the sink, pull the plug, and if it is wired directly, turn off its breaker. A disposal that starts while a hand is near the opening causes the kind of injury nobody shrugs off, and a switch bumped by accident is all it takes. Never reach into the disposal with your hand, even with the power off. Use tongs or long pliers and a flashlight to look down through the drain and pull out anything you can see. If something went down that you cannot reach or identify, leave it for me instead of fishing around blind. Glass especially is better handled by someone ready to take the unit apart if it comes to that.

Freeing a jam from underneath

With the power off, look at the very bottom of the disposal, in the center. Most units have a small hex shaped socket there. It fits the little wrench that often comes taped to a new disposal, or a matching Allen key. Put the key in and work it back and forth. At first it will barely move, and then it should break loose and turn all the way around. That rotates the grinding plate by hand and usually frees whatever had it locked. Once it spins freely, lift out the object with tongs from above. Then look for the reset button described in the next section, since a jammed motor often trips it. Restore power, run cold water and switch the unit on. If it still hums with nothing in it after turning freely by hand, the motor or its bearings are failing, and that disposal is close to the end.

The reset button and a disposal that stays quiet

Most disposals have a small red reset button on the underside of the unit. It pops out when the motor overheats, often right after a jam, and the disposal stays silent until someone pushes it back in. Give the motor a little while to cool, then press the button firmly. If it will not stay in, the motor is still too warm, so wait and try again. If the button is already in and the disposal is still silent, check the switch, the breaker, and the reset on any nearby outlet, because many kitchen outlets carry their own protection that can trip separately. If power is reaching the unit and it still does nothing, the switch or the wiring to it may be the fault, or the motor has quit. That is the point to stop and call. Taking a disposal apart beyond this is not a good use of your evening.

Finding where a leak starts

For a leak, dry everything under the sink with paper towels first, then run water and watch. The first spot that turns wet is the source. Water at the top, where the disposal meets the sink, usually means the seal under the sink flange has failed and the flange needs resetting with fresh putty. Water at the side, where the dishwasher hose connects, is often a loose clamp. Water dripping from the pipe that leaves the disposal points at the gasket at that connection. Any of those are repairs. Water seeping from the bottom of the disposal body is different, because the inside has corroded through and the unit has to be replaced. Sometimes the answer is simpler than you were told. Becca McDonald wrote: “We had a simple clogged kitchen sink issue and an outrageous quote from a large company. Paul came in and found a quicker solution to the problem.” Under the sink, the simple answer is often the right one.

When the unit itself needs work, garbage disposal repair in Mobile walks through repairs and swaps under the sink. If your disposal is doing something not covered here, describe it on the contact page.