Garbage disposal spins manually, but not on its own.

Question

There are all kinds of garbage disposal questions and answers on the internet but none of them seem to address my issue.

My garbage disposal seems to be jammed, but not in the usual way. If I go to run it and look down into the hole with a light it tries to start but then catches on something and stops. If I don't turn it off it pops the reset switch, like it should. To help loosen whatever is in there I pulled out an Allen wrench and tried spinning it from the bottom. To my surprise, it spins totally freely. Finally, I removed it from its mount and (while unplugged, obviously) inspected the inside for anything obviously jammed between the rotator and the grate-like thing. Seeing nothing, I reached my hand in to spin it manually from the top and found that it spins freely that way as well.

Any thoughts on what may be wrong or what I should try next? FWIW, it's an insinkerator and I have no idea how old it is. I just bought the house, but it's a 17 year old house whose kitchen was redone somewhere in that time.

Thanks in advance for your help.

Answer 1

sounds like a mechanical failure, most likely the pin(s) or bushing(s) that hold the anvils in position are worn. when you hand spin it you can't product enough force to replicate the problem. a new disposal should be no more than $125 and maybe an hour to install.

Answer 2

As far as I can tell, they don't have shear pins. And I don't see any gears as replacement parts. All I came across that it might be was a spring.

You'd have to take it apart to find out what's wrong with it.

They're like 100 bucks...

Answer 3

Motors for garbage disposals are single phase capacitor start, induction run. That means there is a centrifugal switch inside that opens once the motor gets close to to full speed to take the capacitor out of the circuit, because it is only needed to make the motor START to spin. If that switch gets stuck open, the capacitor is left out of the circuit from the beginning so the motor will not spin. They get old / rusted / burned out from someone flipping the switch on and off really fast (my daughter did that to me when she was young). It can be repaired by a motor shop, but will likely cost as much or more than a new one anyway. You could try to do it yourself if you are mechanically and electrically astute AND very meticulous about observing how things come apart and go back together. But in my experience, most people are not and this is not an intuitive (or forgiving) type of task.