Author Topic: SHU33336UC/U12 Bosch Dishwasher won't drain all the way  (Read 4980 times)

Offline JohnnyRoaster

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SHU33336UC/U12 Bosch Dishwasher won't drain all the way
« on: August 18, 2009, 10:19:20 AM »
I have checked the drain hose which is totally clear and have hotwired the drain pump which is working fine.  The dishwasher does drain some during the cycle but leaves a couple of inches of water once the cycle is over.  Cancel/Drain does not pump any water out.  I am reading 15 ohms on the drain pump so I think the wiring harness is ok.  Every thing else looks to be in order and float switch and water fill switch clean and working.  The only thing I can think of is the control board which is less than six months old is bad.  I did not run into any errors on the test mode.  

What else could cause the drain pump to run for about two seconds and then stop?  Is there anything I am missing?

Thanks in advance!

Offline JWWebster

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Re: Bosch Dishwasher won't drain all the way
« Reply #1 on: August 18, 2009, 12:28:57 PM »
I don't kmow about bosch but some diswashers leave a little water in the machine to keep the pump seal and bearing from running dry. At the beginning of the cycle they toss out the old water by running for a few seconds.
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Offline JohnnyRoaster

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Re: Bosch Dishwasher won't drain all the way
« Reply #2 on: August 18, 2009, 12:53:04 PM »
This is more than just a little water in the sump.  The water is about two inches deep and stops just short of the door opening.

I am not sure if there is a timer on the control board that does the final drain or if it relies on the water switch.

Offline JohnnyRoaster

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Re: Bosch Dishwasher won't drain all the way
« Reply #3 on: August 18, 2009, 01:53:48 PM »
I just noticed there is a back flow valve that could be allowing the water in the drain tube to flow back into the sump after the cycle is over.  Has anybody else ever run into this?

Offline JWWebster

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Re: Bosch Dishwasher won't drain all the way
« Reply #4 on: August 18, 2009, 02:20:59 PM »
I have heard of a backflow malfunction where the disposer let junk flow back into the dishwasher. Don't you loop the drain hose to prevent that? I hate dishwashers.
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Offline JohnnyRoaster

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Re: Bosch Dishwasher won't drain all the way
« Reply #5 on: August 18, 2009, 02:38:26 PM »
Yes there is a loop but no air gap.  The hose is about eight feet long and could syphon the waste water back from the other side of the loop without the back flow valve in place.  I will try shortening the hose and see if I end up with less water after a cycle.  I ordered the back flow valve for 3.65 and paid 4.95 to have it shipped :-\

Offline JWWebster

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Re: Bosch Dishwasher won't drain all the way
« Reply #6 on: August 18, 2009, 02:43:14 PM »
their ain't no outlet for appliance parts near you?
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About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair and other general BS I love to post. The letter sends me email.
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Offline JohnnyRoaster

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Re: Bosch Dishwasher won't drain all the way
« Reply #7 on: August 18, 2009, 03:54:30 PM »
I think the Bosch parts are pretty hard to come by.  Even the repair guys have to order them I think.

 

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