On the surface, a dishwasher motor might seem to be a complicated part of an even more complicated appliance. There are a number of different things that can go wrong with it. But, before you call a repairman, or, even worse, replace your dishwasher entirely, try running through some things that might save you some money and hassle.
Remember, as always, to make sure the power is entirely cut off from any appliance before you start working on it, and especially before you start working on electrical components. It is also a good idea to shut off the water supply valve, usually located underneath the sink, to avoid any wet accidents.
Motor Seems Stuck
If nothing happens at all when you turn your dishwasher on, the power may have gotten cut somewhere. Check the wiring, fuses, or breakers to make sure they are all still correctly connected or functioning. Many dishwasher motors get stuck if not used for long periods of time, as well. In this case, you will need to open up the casing and manually spin the fan blades on the motor to knock it loose.
A door that is not closed or latched all the way could contribute to a seemingly-dead motor, as well. Make sure there are no objects jamming it open, and that there is nothing lodged in the latching hook. A dead selector switch or timer motor could also be the culprit.
Motor Seems Noisy
Ball bearings can make quite a racket in a motor when they begin to wear out. As the grease gets used up, the bearings will rub against each other and create rough surfaces that make a lot of noise. Bearings also wear out more quickly if they are exposed to water, which would occur if the spin seal is worn out. In this case, you would need to replace the seal to avoid water leaking into places other than the motor.
A noisy motor could also be caused by loose mounting. As the motor runs, vibrations can cause the mounts that hold it in place to work loose, causing rattling. Make sure all the screws and bolts holding the motor in place are tight and secure.
Motor Hums but Doesn't Come On
Occasionally, over time, motors can just burn out. If you've unjammed it manually by spinning the blades, and it still does not come on, it may be time to replace it. It is still receiving power, or else it wouldn't hum. It's very difficult and time consuming to service a burnt out motor, so replacing it may be your only option.
Water is Weak
This is a common problem that could seem easy to blame on a dying motor, but the most common cause for this is simply low water pressure in your home. An easy solution for this is to turn off other sources of water consumption in your home while you're running your dishwasher.