Hi, I have a draining problem with a Bosch SHV4803-UC12 dishwasher.
Under normal operation, the basin dosen't drain.

When I disconnect the drain hose from the wall and redirect it to a
bucket, it drains fine. The motor works, I can see water going through
the little transparent plastic trap thing under the panel, and I can
measure 120VAC getting to the motor. It *sounds* like it's working
fine too, but I can't be sure.

The household-end of the drain hose goes into a pipe in the wall, not
any visible above-sink air trap or anti-siphoning mechanism that I can
see. It just disappears into the wall, not the garbage disposal,
y-connection, etc.

When I pour water into the drain hose into the wall from above a
certain level, water continues to go down, and there is little
blockage. If I pour too fast, it'll back up, but it quickly clears.

If I take the drain hose and lower the end to a foot or so above the
floor, water comes up, indicating there is water sitting at that level
somewhere else, and I can't pour water down.

This indicates there is water above the drain somehow, and when I blow
through it I'm somehow blowing this extra water through the pipes. I'm
really not sure what's going on. If I stop blowing before it's clear,
I can hear water sloshing in the pipe back and forth, as though
something is pushing it back.

In all cases I can blow through the hose, and after *much* difficulty,
can eventually clear the hose and blow air, though it's still
difficult. When I then pour water in, it again backs up. We've tried
drano, etc., to clear it, but I'm pretty convinced it's not a gunk
blockage, since it'll take a LOT of water if I pour it in from above a
certain level.

A plumber told us that this is normal and nothing is wrong with the
drain in the house, and that sometimes a dishwasher needs backpressure
to keep the pump primed. But I've been reading that often this is to
prevent unwanted siphoning of the drain.

But I know the drain in the dishwasher can pump water into a bucket.

Is the dishwasher drain motor supposed to overpower the backpressure in
the drain? In other words, is my motor somehow weak and damaged,
enough to pump the water into a non-backpressure bucket, but not enough
for the drain? I don't get it.

Is my drain clogged, or do I need a new motor?

thanks
michael

In article .com, writes:
| Hi, I have a draining problem with a Bosch SHV4803-UC12 dishwasher.
| Under normal operation, the basin dosen't drain.
|
| When I disconnect the drain hose from the wall and redirect it to a
| bucket, it drains fine. The motor works, I can see water going through
| the little transparent plastic trap thing under the panel, and I can
| measure 120VAC getting to the motor. It *sounds* like it's working
| fine too, but I can't be sure.

Does your Bosch use a separate drain pump motor, a positive solenoid valve
to redirect the main motor, or one of those little free-floating flappers
that is somehow manipulated to select between drain and circulate? I've
observed that the latter seem to be very dependent on the "correct" back
pressure. See:

http://groups.google.com/group/alt.h...315e0466cec0df

I suppose even a separate drain pump might now depend on the preferred
(mandatory?) open-drain hookup. For what it's worth, I just installed
a new KitchenAid S-series which uses a separate pump. I thought I was
going to finally have to bite the bullet and make my drain configuration
(which is like yours) "standard" (a non-trivial task) but it works fine.
Still, the new unit is much more flimsy than the ~20 year old KitchenAid
it replaced...

Dan Lanciani
ddl@danlan.*com

No, this has a separate drain pump. This weekend I'm going to remove
it and open it up to see if there's anything stuck in the impeller or
whatever. Maybe that's sucking power away from the motor and
preventing it from developing proper pressure. I'm doubtful.

Michael

Hi,

*Sounds* more like the house drain is restricted than the d/w drain
pump is bad. Run a temp hose from the d/w to a bucket/pail and run test
a rince cycle to see how the d/w reacts.

jeff.
Appliance Repair Aid
http://www.applianceaid.com/

Hi,

I disconnected the hose as you suggested and ran the drain cycle.

It appears the drain motor isn't strong enough to pump the water up
above about the level of the main basin, or slightly above. This is
far belw the ~3feet or so of the water level in the drain pipe in the
wall. This suggests a bad drain pump motor assembly. However, the
motor impedance reads 16.5 ohms just like it should (according to the
repair guide for this particular model).

Do you think it's more likely to be a mechanical problem in 1) the
motor or 2) the pump assembly? Eg impellor broken, bearings, gunk,
etc. I have convinced myself it's not electrical.

thanks
Michael

Hi,

ok, found the problem. The drain impeller vanes were broken. I'll
order a new assembly tomorrow.

michael

Glad to see you are getting somewhere with it!

The drain impeller vanes were broken

Wonder if something hard like a bone or such got in there?!?

http://www.repairclinic.com/referral.asp?R=153&N=935403
Drain pump assembly SHV4803UC-12

jeff.
Appliance Repair Aid
http://www.applianceaid.com/

Yeah it's weird. We've never run the dishwasher without *both* the
coarse and fine filters, so I've no idea how they broke.

michael