Dishwasher draining question

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Runs with bison, Jun 26, 2012.

  1. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    We don't seem to have a forum for this, so I'm asking here in case someone has experience troubleshooting these.

    Appliance: Whirlpool DU1055 "Quiet Partner I" dishwasher (~5 years old, in home when purchased)
    Problem: While away on vacation for ~10 days the bottom of the washer slowly filled with clean looking water and leaked a little onto the kitchen floor. Since then I've noticed that after the whole cycle is complete there is a small water level left just to the edge of the black gasket for the central pump assembly. It is clean enough that I have to stick my finger down there to detect it. Is this remaining level intentional or an indicator of a drain pump issue?

    Conditions and actions taken:
    1. No problems with the dishwasher before. Cleans well, no gunk in bottom, no grit or film in rinse. We do quick scrape to trash and rinse of plates/bowls in sink while waiting for water draw to reach temp.
    2. Typical cycle for us is the 150 F sani rinse, with no drying cycle. The hot rinse is sufficient for drying the dishes and in my experience with other dishwashers drying elements can damage dishware.
    3. I checked water pressure again it is in the 70-75 psi setpoint range, but found it spiking into the 100+ psi range at least once over several days. Suspected that perhaps some water was leaking into dishwasher during spikes. So I flattened the system, left a faucet open and checked the thermal expansion tank pressure figuring it needed make-up air--something I had been meaning to do annually anyway. It was running about 25 psi so I reset it to 75 psi to match PRV. Pressure spikes are gone.
    4. Have been manually running drain cycle after each load. This is emptying the basin completely from what I see.
    5. I'm not seeing any evidence of drain back/leaking check. When the overfill happened before there was no water use occuring at all in attached sinks and the dishwasher had been emptied just before we left.
    6. Haven't noticed any new/unusual sounds, never have had any broken items in the washer.

    So the main question is whether or not the machine should drain itself fully at the end of a full cycle (minus heated dry)? If the answer is "no" and it maintains a level in the pump assembly (perhaps to protect it from overheat when the drying element runs?) then all is probably good. If the answer is "yes" it should empty fully, then is there some sort of level sensing switch at fault or does this indicate a weakening drain pump? Either of those two could also impact how well it removes wash water before the rinse as well.
  2. kreemoweet

    kreemoweet New Member

    Messages:
    371
    Location:
    Seattle. WA
    I've yet to encounter a dishwasher that drained "completely". Probably a physical impossibility with a centrifugal pump, and then you always have
    drainback from the high point of the drain hose.
  3. Chad Schloss

    Chad Schloss Member

    Messages:
    329
    Location:
    USA
    the thing that lets water enter the dishwasher is an electrical solenoid. sounds like some water could be seeping past the seal that is inside the solenoid. maybe some crud got on the plunger? maybe the too high water pressure messed with the seal and it is leaking a little past the seal now?
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    On most I've seen, the cycles run (mostly) by time. If there's anything obstructing the drain, in the time allowed, it might not drain. But, most do leave some in the bottom, regardless. Now, my exposure on this isn't huge, so it might be tainted..
  5. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    I was guessing that it was a timed drain cycle as well. Since I hadn't noticed the level previously it wasn't until the vacation excess water episode that I began watching it. The problem with a timed cycle is that as the drain pump impeller wears it is going to remove less and less water fouling up the rinse cycle.

    The interesting thing was that manually selecting the drain cycle after the sequence has finished seems to empty the sump or at least move liquid low enough that I couldn't find any sign of it.
  6. wondering

    wondering Member

    Messages:
    106
    I have a Kenmore which is a twin to yours. I had a problem with it letting water "drip" in till the bottom would be covered, but would only do it occassionally. Also had the problem with it not draining fully. If operating normally you should see no water in the bottom after it finishes. This is why when you do the 2nd drain it empties tub,if that water was supposed to be left in there it would not pump out on the 2nd drain. You can take the arm and cover off and check to see if your chopper and the black check valve to the right of the chopper looks ok. There will be a small amount of water in the bottom of the sump but this is normal. Since yours is cleaning well, your chopper should be ok. Sometimes they start clogging and then you will have washability problems. I had a bearing go bad in my motor but I used it a long time and just let it scream, until it started leaking. I then replaced the complete motor/wash pump assembly. You might want to check your drain pump. It is located to the right on the wash module. It just twist off and you can check to see if anything could possibly be in there. It might also help to run a bottle of Dishwasher Magic or the Finish Dishwasher Cleaner through it. That might help if it has build up on the hoses or impellers. Some of these no phosphate detergents really seem to clog things up now. My problems all started when I was using Cascade Gel and it just clogs everything. I do not use any gel/liquids anymore. Hope some of this helps...
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    The DW pump can move the water to fill the hose and discharge it into the drain line, but it CANNOT pump any air to shove the last of the water out of the hose. Therefore, when the pump stops, the water between the high spot in the hose and the DW, will drain back. The amount of water in the hose will determine whether any appears in the bottom of the DW or not. IF the DW fills with water when the house is vacant and no one is using water in the sink, then it has to be a fill valve malfunction.
  8. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,792
    Location:
    Long Island, NY
    For what it's worth, there are dishwashers that have discharge hoses with built in check valves, which if this is one of them, could be faulty.
  9. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    Thanks for the observations and suggestions. I haven't pulled anything apart yet, or pulled the unit out recently to look at it (I pulled it out a few years ago to do some work adjacent to it.) I've been running cascade gel in it the whole time. Haven't seen any sign of anything clogging. Our water is moderate in character and I don't see much build up in waterlines or from drips.

    I'll keep watching it, particularly to see if it accumulates any additional level when it isn't run for a long weekend or such. If it gives any more signs I'll start pulling what you mention, plus the drain hose to look for any issues.

    Might have just been a fluke
  10. Chad Schloss

    Chad Schloss Member

    Messages:
    329
    Location:
    USA
    a fluke does not fill your d/w when no one is home...
  11. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    The drain pump does draw the level down to an undetectable level when the "drain" option is chosen after a load. Whatever drainback there is isn't much. As BobL43 notes, some of these have built in checks--until I pull it out, I can't tell.

    I suspect you are correct about something happening with the fill valve. My first guess is that it was the result of high water pressure because of the thermal expansion tank needing to have its charge pressure reset. With that resolved it might not happen again.

    At least I've learned something about these machines, repairs don't look too difficult and parts prices aren't all that bad.
  12. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    It does if it was a one time piece of something keeping it from tightly sealing, or if it might have been a thermal expansion issue, which I have since resolved.

    Until the issue can be repeated, it's a fluke.
  13. Chad Schloss

    Chad Schloss Member

    Messages:
    329
    Location:
    USA
    thermal expansion? from an over pressurized fill valve? just trying to help you out. think what you want. fresh (clean) water only enters from one location and leaves from another.. if no one is around to turn the machine on or wash dishes, how do you think the machine filled itself?
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