I bought a new AEG dishwasher a few weeks ago.  After finishing the
sample pack of detergent that was supplied with the dishwasher, I
started using the brand of detergent that had worked fine with my old
machine.

Then, a rather strange problem appeared.  In a certain part of the
washing cycle - some minutes after the detergent has been added, and
the water temperature has reached around 50 degrees Celsius - the
dishwasher starts to generate a faint "whistling" noise.  The sound disappears
when the water is further heated a few minutes later.

The instruction manual lists this problem in their troubleshooting
guide.  It tells that the sound is harmless, and recommends using
another brand of detergent.  This solution works for me.

But I wonder:   How is this sound generated when certain brands of
detergent is used?

Some other information that may be useful:
- The noise does not appear if the machine is run without any
detergent.
- The machine is supplied with extremely soft water.

Hi, thanks for your question.
I had never heard of that before, but I found a few interesting
tidbits on the problem. The reason that some detergents cause whisting
is that they react more quickly at a certain temperature than others,
creating small suds. Thus,as it is funneled to the dishes, it creates
a great deal of pressure and as the bubbles pop and air is forced
through a small area. As a result, a whisting sound is heard. The soft
water that you use facilitates greater sudsing. So,  the detergent
that you use that does NOT produce the whistling likely contains an
anti-foaming agent that inhibits this pressure.

Some detergents don't produce this pressure because they produce less
suds, sometimes none at all. Even the detergents that produce
whistling produce a small amount of suds, but even a little extra is
often enough to produce the sound.


Related Links

Facts About Dishwashing
http://www.sdahq.org/dishwash/dishwashing_fact_sheet4.html

SDA: Soaps and Detergents
http://www.cleaning101.com/sdalatest/html/soapproducts1.htm

Dishwasher Troubleshooting
http://www.geocities.com/~uabill/UABillDishwash3.htm#Level5


Google Search Terms Used

"Dishwasher detergent" ingredients
://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22dishwasher+detergent%22+ingredients&spell=1

Dishwasher troubleshooting
://www.google.com/search?q=dishwasher+troubleshooting&hl=en&lr=&ie=UTF-8&oe=UTF-8

Thanks again. If you need any clarification, please let me know.
Anthony (adilorenga)

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Request for Answer Clarification by blazius-ga on 21 Apr 2003 23:43 PDT

Your suggestion sounds probable, but I do not find much support for
the "whistling bubbles" claim in the documents you linked to.  How did
you think of that?  :-)

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Clarification of Answer by adiloren-ga on 30 Apr 2003 18:47 PDT

I corresponded with the diswasher manufacturer for specific information.

I got a probable answer, but the answerer has still not replied to my
answer clarification request (after 5 days).  A better
supported/clarified answer would have earned 4 stars.