Sorry for the long description that follows, but I think it is best to give the full sequence of events.
I have a Bosch dishwasher Model SHE55R55UC/64, manufactured and installed Dec 2011.
About 1 year ago (Feb 2014) the dishwasher stopped working during a wash cycle. There was water left at the bottom, the dishes were not properly rinsed and it would hum if we tried to run it again. I called Bosch, the technician fiddled with the drain pump and got it working, but it was not as quiet as before. The technician said it would be somewhat noisy and at some time we might want to replace the drain pump.
Everything worked fine (reasonably quiet) until 1 week ago, when the same problem started again. I manually pumped out the remaining water, then removed the filter and screen at the bottom of the enclosure, removed the drain cover and examined the drain impeller. Everything looked OK. The impeller would turn by hand, although in steps (not totally smooth). I also removed and examined the backflow valve, everything looked OK.
I then removed the kick plate and removed various parts to get to the drain pump and removed it. I put a cheater cord (AC cord with spade connectors at the end) on the pumpís terminals, it worked fine (spun smoothly and was quiet).
I put the pump back in, poured water into the bottom of the dishwasher, and again operated the pump using the cheater cord. It pumped the water out, although it was noisy. Putting some pressure against the pump body made it quiet.
I reassembled everything back and did a wash cycle, everything was working fine, although the pump continued to be noisy (but muffled by the insulation). So, not sure what the original problem was and what solved it, or why the pump was very silent by itself but noisy when put back in.
Ran another load 2 days later. The cycle starts by draining any water, then it is supposed to fill, but I could hear sounds but no water coming in. After reading some internet suggestions I poured water into the bottom of the washer and ran it again. Now it did fill with water and the cycle ran, but when it came to drain it just made loud humming noises but no draining.
So, one more time checked the impeller, everything is OK. Ran an empty cycle, water drained out OK and the dishwasher filled and ran. Drain pump is still somewhat noisy. Also, it does not drain continuously. It runs and pumps some water out, then stops, then runs again in maybe 10-15 seconds, then stops, and so on 3-4 times. Does that indicate the controller is sensing a problem and re-trying the drain a few times?
So, at the end not sure what is the problem. Not confident it is fixed. Any suggestions on what is the problem and what I should do Ė the obvious answer is change the drain pump, but not sure if it is the culprit, it runs very quietly and smoothly if I pull it out and test by itself.
Also, a few questions:
Is there a test program for this model? Iíve seen some for others which involve pushing a combination of 2 buttons and starting the machine, but none for my model. Tried pushing various buttons but none seemed to activate a test program.
This model is fully automatic, it doesnít even tell you where in the cycle it is (fill, wash, drain, rinse etc), nor is there a way to advance through the cycle, so it seems the only way to test anything is to start at the beginning and wait for a full 2 hour cycle to go through. Is there a way to advance through the cycle manually for test purposes?
Any help is much appreciated.