Tip & How-To about Dishwashers
I own a Bosch SHU9915UC/U11 dishwasher and would like to share my experience in repairs so that others may learn from my adventure.
I am a troubleshoot and repair person, I have been all my life. I picked it up from my dad, used it as an nuke electrician in the navy for 8 years and have used it for the last 12 years in the building automation and controls business.
Dishwasher fills with water when off- (fill valve leaking by)
We noticed water inside the of the dishwasher some time after the cycle has been completed. I figure the unit just didn't drain down all the way after the last cycle. I run the dishwasher through a Rinse and Hold cycle, when it is done there is no water at the bottom. At this point I'm hoping that everything is better and I can get back to better things.
A few hours after the next cycle there is a puddle on the floor and one in the basement. Now I am suspicious of the water valve and decide I'll give the valve a once over and see if that fixes the problem.
I take the bottom front panel off and follow the water line to the water valve. Its a brass device with an electrical coil on top of it. It is attached to the dishwasher with a couple torque screws.
I had to shut the hot water off to the whole house so that I could take the water line off of the unit. After I shut off the water, I opened a nearby hot water valve so that I could bleed the pressure off of the pipes. I was pleased when I loosened the fitting on the valve and no water came out. I had been replacing the water pipes in my old house with copper lines and had another isolation valve that I was able to install right off the hot water line and was able to then turn on the hot water to the rest of the house.
Back at the valve on the dishwasher I backed the two screws out so that I could remove the valve and get a closer look. I wanted to disconnect the wires on the valve and found that the hot lead to the valve remains "hot" even though it is deenergized. This is another reason why you should always follow the "Disconnect the power before servicing" rule.
The water and power are finally off. I disconnect the hose on the back of the valve and pull it out. I put the valve to my lips and blow. I can hear air hissing through the valve, obviously the seat has some gunk in it or it is marred. I took the valve assembly apart and found out that the valve body has two functions, filter and fill valve. From the looks of thing I could have gotten to the filter just by removing the four screws on the valve and I would not have had to disconnect the water line. Of course the water would have still needed to have been shutoff.
I take the time to clean the filter out. After 6 years of use in an old house, its pretty dirty. If the filter gets plugged, the dishwasher may have a hard time getting enough water to run properly and would most likely cause the cycles to run longer than normal. If you have an older dishwasher you may want to clean that filter. It may not be in the same place but it should be before the water valve in order to help keep junk out of the valve.
After pulling the filter out, I notice a little black washer right behind it. I thought that it may be part of the valve seat assembly and tried to get it out. The valve is so old that the plastic post that the rubber washer is on turns to mush as I try to take the washer out. This can't be good. I get the washer out but the post and the seat area are damaged. Under the washer, there are actually more holes. If the washer was not there it would just allow more water through the valve. This problem rears its ugly head later.
I decide to move to cleaning the valve out another way. I carefully beat on it to cycle the valve manually. As I tap it (again carefully) I can feel/hear the plunger moving up and down inside the valve. I find that I can blow water backwards through the valve. I do this a few times to flush the seat out. After a bit I try to blow air through the proper way and I can't do it. This is a good sign. I manage to clean up the place for the washer and get it back into place. Its not perfect but it should work well enough until the new valve shows up.
I have by now decided that a new valve is definitely needed. The corrosion of the plastic inside the valve is enough to scare me. This valve is the only thing between my hot water line and a flooded kitchen/basement.
At this point my water valve doesn't leak anymore and I put it all back together.
Odd noise (water hammer from too much water flow)-
First run of the newly repaired dishwasher produces and occasional loud banging noise. I'm guessing its water hammer from air in the lines causing the water valve to make noise. When it keeps happening after a few uses I begin to suspect that little black washer and the deteriorating plastic. If the valve is letting too much water through it could cause banging as it tries to shut. So I head down to the basement and throttle that newly installed valve back a bit to limit the amount of water going to the dishwasher. This seemed to help with the noise.
Pump down even when door is open-(water in drip pan)
Again we load up the dishwasher and after three or four hours the dishwasher is still making noise. When I open the door, the pump keeps running and I notice that the soap is still not used (no water ever ran). I start pressing buttons like a mad man but the thing keeps pumping. Turning off the On/Off button makes it stop but nothing else seems to. There is no water in the dishwasher so I'm confused. Thoughts of the circuit board being smoked go through my head but I'm not ready to give up yet.
I read a few more things on this fixya.com site and checkout my door switch which seemed to work just fine and I become interested in the float assembly. Its one of those things that can't be gotten too easily. But I'm able to see part of it underneath. There is a red post (looks kinda like a suction cup gun "bullet" stick) over on the left side of the unit behind the water valve. I can reach a screw driver back there and move it up and down. I can hear it click when I push it down. I hold it down and turn the power on to see if the unit will run with the door open. It doesn't. I am now very suspect of this float assemble and decide to get a closer look. I disconnect the water and the power again, pull the unit out from under the counter. I am able to pull the side panel off by removing a couple screws on the front face which hold a weather strip looking thing in place (used to seal a gap between the counter and the dishwasher). Once the side cover is off it is easy to see what is going on. There is water in the drip pan. I didn't even know that there was a drain pan but now I do and water in the pan indicates that I have a leak. I assume that it is just the hose on the back of the water valve and I adjust the wire clamp a bit more. I figure that it will eventually quit and put it all back together again after draining the water.
The first run of the unit got about halfway through the cycle before getting into the same stuck in drain mode condition. So now water is getting into the pan faster than before. Great. I think about this a little more and decide it can't be the hose off of the water valve because of the way the unit is made, that line is never pressurized. The water comes into the unit and basically spills into a cup on the float device as the unit needs water. The use of the little black washer in the water valve becomes apparent. It is used to limit how fast the water enters the dishwasher. The banging noise probably indicated that the washer fell out of place and the inrush of too much water was traumatic to the water valve. The inrush of water also caused the cup to over flow and the water was caught in the drip pan. I wish I hadn't cleaned the filter now.
Fortunately for me I installed that valve and was able to close it off even more. This limited how fast the water could enter and the cup no longer over filled. So far the unit is still running after a few more uses and hopefully it will keep running until I am able to replace that valve assembly with a new one.
I know its a long read but I sure hope it helps a few people out. Good luck and be safe! Electricity can kill and a flooded basement will ruin your day.
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