Date:         Wed, 26 Jul 95 0:29:42 EDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         jag@cs.rochester.edu
Subject:      Westy sink waterpump


Some time ago there was some discussion about the westy's submerged-
in-the-tank water pumps. (Used in late westys, 82 and later I believe. 
The earlier westy's had the water pump mounted outside of the tank).

My pump had been getting unreliable lately, and I decided to take
a close look at it instead of just buying a new one. The pump is a VDO
brand, and has the marking 7l on it. This could be a model, or a
liter/minute rating.

The pump looks like a miniature of a submerged style basement sump pump.
At the bottom is the pump housing, and impeller. It's all glued together,
but by carefully prying with a screwdriver I managed to open the lower
part containing the impeller.

I experimented a bit with it open this way, and found that I could
get the pump to start and run fine if I pushed a bit on the motor
axle. When put back together again the pump would run a few more
times, but then die. At this point I suspected either bad contact
in the commutator, or that one or more, but not all, windings were
bad. 

To get any further I needed to get access to the electrical motor in
the upper, sealed part of the pump. This proved harder to do than
opening the lower pump housing. Prying with screwdrivers and knives
just broke off pieces of plastic, but wouldn't move the top cap off.
In the end I ended up sawing carefully around the flange of the top
cap, and managed to saw away the glued part without wrecking the
flange itself.

Once I got the flange off to my surprise and horror black, rusty water 
poured out. It's a wonder the pump had at all turned this way. I couldn't
get the DC motor out of the plastic housing. Maybe it's integrated into
the housing somehow. Maybe it's just rusted in there. 

The good news is that I got the motor working again by flushing out
the water and rust with "liquid wrench". I also took out the water
seal on the shaft between the upper motor part and the lower impeller
housing. There is just one, somewhat flimsy looking rubber seal.
I'm no longer surprised my motor was full of water. In fact I wonder
how that seal could ever had kept the motor dry through natural
pressure variations caused by different tank water levels, and
varying outside temperatures.

For a while I though that since the motor appeared to be able to
run even when full of water, and it would be hard to keep the water
out of there if the housing was filled with air (since air is easily
compressed, allowing water to enter), maybe it would be a good idea to
fill the housing with a non-corrosive fluid instead. I contemplated
filling it with liquid wrench for a while. Then I realized that it
would be worse to have the liquid wrench leak into the water tank, than
having water in the pump. 

Before reassemblying I stuffed the water seal with grease, and lubricated
the motor bearing with a little light oil. The housing was glued together
with epoxy. The pump has worked fine since this "overhaul".

If I were to do it again I would use a simpler procedure. Since the
motor wont come out anyway it would be enough to drill an access
hole in the top of the motor housing. There is a 20mm empty space between
the upper lid and the motor. The motor can be drained and lubricated through 
this hole. To get to the seal, the lower part has to come off though.

/Martin