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my dishwasher isn't draining.

I checked the drain hose and it's clear enough that I could blow air through it.

  • I removed the drain pump, model #W10158351B I measured the resistance between the two connector pins: ~24ohms.
  • I connected the two leads to a 120VAC supply. The impeller would turn maybe 2-3 degrees and stop, with the motor making a hum. I did this with the polarity only one way (randomly chosen).

I think this is pretty conclusive that the motor is dead but I'd like to be sure before I buy the replacement.

I'm also surprised to find water has been leaking out of the pump bit by bit. I presume that means water has made it past the impeller seal and is generally bad?

Is my drain pump bad? Are there other tests I should perform?

Thanks!

  • does the impeller turn freely by hand? – pancho018 Oct 10 '16 at 20:45
  • It did. There was some resistance, but not a ton. – RobotAndy Oct 11 '16 at 12:50
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I have the same problem you had. I am not sure of the proper impedance you should have. One internet repair place says 200 ohms for a good motor. I did the same thing you did (same problem - dishwasher not draining) lines were clear to disposal - I also exercised the check valve which is in the 90 degree black elbow right off the drain pump on my machine (Whirlpool model WDF760SADM) forward and backward to ensure it flowed and would stop flow in the reverse direction, which it did. I do not have leads that are compatible with the motor to check that it runs. I am going to replace the drain pump to see if that is the problem. Also, the jerky motion on the impeller is due to the magnetism on the motor.

  • It's been 2+ years since I posted this. After sitting out of the dishwasher for a few days, the old motor just decided to start working again and has worked fine ever since. I figure it dried out and became fine. I actually bought a new replacement motor and have it sitting in the box. I'll measure the resistance on it and post back. – RobotAndy May 23 '18 at 19:00
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For future reference, before you take the thing out:

Unplug and replug the power and switch it on. Three things should happen in a reasonably modern dishwasher.

  1. Power light will become bright

  2. The water inlet sensor will either open or fail-close on pressure of inlet water. Closed switch means no power to dishwasher.

  3. The drain pump will do one or two revolutions at minimum

It can be the water inlet sensor or the water inlet pressure that is fouling up. Since the sensor is fail close it should get hot to the touch (by just a few degrees, don't worry) over time if it is working. So check that it gets warm. Some models also have lights to indicate SENSOR OK, that saves a bit of waiting. If that isn't working, check the water on the inlet side. Remember you have to power down the machine with the plug to reset the switch, if you find you have a valve closed. If the water is fine, the sensor is fine, the drain swamp is reasonably clean, and still no "chugs" from the pump - take it out for manual testing.

Any leakage or failure to run should be considered graveyardable offenses. It just isn't economically reasonable to do anything else than getting a working one - scrap dealers usually have tonnes of them.

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With the pump still on the machine:

  1. Use a multimeter on the continuity setting check each lead to see if either one has continuity to the frame of the machine. If it does, that is bad. This is an unlikely culprit.

  2. Put the multimeter on the ohms setting. Put the probes on the two motor contacts. Anything in the 10s to 100s of ohms should be considered good. If it is higher than hundreds, it is possibly bad.

If it passes those tests, remove the pump and attach 120v AC (or whatever the specs say on the label on the pump depending on the country you live in). You can do this by taking an old power cord from a junk appliance, tool, or light and stripping the ends of power and common. Attach them to the motor leads and plug it in keeping hands away from those wires. If the impeller spins it is good. If it doesnt spin it is bad.

If it spins, Id suggest looking into the impeller housing- there may be a small chip of glass or ceramic in there that could be jamming the impeller.

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