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cjc  
#1 Posted : Sunday, November 30, 2008 6:33:49 AM(UTC)
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cjc

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I have a Bosch SHX46B dishwasher that about a week ago started making strange noises during the cycle. The noises happen two times during a regular cycle: once soon after the beginning of the cycle, once later towards the end. The duration is variable, lasting from 30 seconds to a few minutes.

The noise is best described as a "moaning" vibration that reverberates throughout the entire house via the copper hot water pipes. Consequently, we can no longer run the dishwasher before going to bed.

Over the long weekend, I disassembled the shutoff valve under the sink and cleaned it out, thinking possibly there was an obstruction in the lines causing a "whistling" effect. While the R&R was definitely needed, it did not solve the problem. I next verified that the impeller (well, I think it was the impeller--blue spinning vane in the bottom of tub--anybody have a parts breakdown diagram?) was spinning freely and not clogged.

Ran the cycle again and, when I heard the noise, noted that I could get rid of the noise and vary the noise by turning the water shutoff valve under the sink.

I removed the water valve assy. and noted that there was some gunk collected along the sides of the inlet screen. I cleaned it then attempted to test the valve using 120VAC applied to terminals, but did not get what I expected.

How is this valve supposed to work? Should I be able to blow air through it (constricted, but air will still pass) when it's out and disconnected from the dishwasher?

Does anybody know where I could get a troubleshooting or service manual for this dishwasher?
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cjc  
#2 Posted : Sunday, November 30, 2008 2:50:35 PM(UTC)
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cjc

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Okay. I did more tinkering/troubleshooting this afternoon and discovered the following...

I believe that it's the water valve assembly. I removed it, cleaned it (screen on inlet had some stuff gunked up on there), wanted to try to check operation on the valve but could figure out how it was supposed to operate. I suspect that there's some kind of internal temp-sensor switch that doesn't let it operate when inlet temps aren't high enough.

Anyway, after cleaning, I reconnected the valve and ran a rinse/hold cycle. About 8-10 minutes into the cycle the valve started buzzing. I confirmed that it's the valve that is buzzing because I put my hand on it and can feel the vibration strongly. The vibration is not strong in the hose on the outlet side (through it's strong on the copper line running to the valve). Also, if I cup my hand around the valve the sound gets attenuated.

It's now almost 20 minutes into the cycle and it still hasn't stopped buzzing. It sounds like when I was a kid and made a buzzer by wiring up an DPDT relay through itself so that when the relay was energized, it turned off power to its coil.

My suspicion is that, if there's some kind of internal thermal switch, it's hosed and is doing something similar, and causing the buzzing/vibration.

Can anybody confirm the operation of this valve and its integrated solenoid? Is there anyway to troubleshoot this beast other than getting a new one and trying it out?

I suppose it could also be vibrations in the line between the shutoff valve and the valve assy. itself, but I pulled that line and ran it clean. Maybe I need to just try running that line free into a pan or something at full blast.

Any help appreciated.
denman  
#3 Posted : Sunday, November 30, 2008 5:08:31 PM(UTC)
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denman

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Your Model Number is short a couple digits.
Just search find parts section of this site with the full part number. I looked at one unit using just the SHX46B the valve was around $24.00.

You could check that it is getting 120 volts.
If it is getting 120 and buzzes replace it.
THIS FORUM IS DEAD!!!!!!!
cjc  
#4 Posted : Monday, December 1, 2008 12:04:53 PM(UTC)
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cjc

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As a quick followup, I found the part locally (i.e., could install today) for $19.50 and installed it. The dishwasher has run one full cycle without problems so hopefully that got it.
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