This is an old article from 2004. I keep it around as reference for others
who are interested in restoring older commercial espresso machines.
The only enhancement I implemented was a boiler insulation which saves about 15%.
The machine is in daily use, brewing espresso based on Monsooned Malabar from
Caffé Fausto, it performs well and
I would not want to be without it.
Cleaning up a 1 Group WMF Espresso (a Cimbali M30 Bistro in
I got lucky on e-bay and bought a WMF Espresso 9503 for a
reasonable price. This is a commercial
machine built by Cimbali for WMF. It has a slightly different
exterior (more stainless steel, black bottom instead of gray and blue buttons
instead of green ones) and a slightly different internal tubing (cold water
is through steel mesh enforced and insulated flexible tubing instead of fixed
copper pipes) but is otherwise identical to the Cimbali M30 Bistro. The
machine is no longer sold by WMF, they seem to focus on super-automatics only
for their professional line.
The machine was built in 1992, and seems to have been used in the army
until 2002, then it was stored in a (thankfully heated) garage until I bought
it. My first attempts at starting it up lead to the boiler filling and
heating, but no pump activities when pressing the brew button. Water came
out, but that looked more like line pressure. Steam and hot water where
working. The programming of the buttons would not take.
With the help of a fellow espresso freak I started to look closer (the picture quality is not necessarily
briliant, they where taken with a PS digital to have a reference for
We took apart the pump (a 24V Ulka). The steel piston was not moving in
it's brass enclosure. So I figured, if the pump is already blocked by scale
the rest of the machine is probably totally scaled up.
We started taking pictures and took the machine apart. This is where we
made our first error. We did not take enough pictures of the individual
components that where taken apart, thinking that placing them into their own
boxes each would be sufficient. It would have been better if we would have
taken also pictures of the disassembly of the valves and flow
The next step was to clean out the old coffee remains and the scale. We
used about 1Kg of citric acid and quite a bit of Puly Caff. Unfortunately,
when soaking copper tubing together with other metals in citric acid, the
other metals (brass, nickel, some steels) will aquire a copper coating,
especially if there where already traces of other things on the metal. If you
do not leave the parts in too long, this will be no issue, if you leave them
a little bit longer, you can still rub off the coper sheen. If you leave them
too long, the copper will be there permanently. Not really a functional
problem, but not nice looking and a potential source of verdigris.
De-scalers based on formic acid might be better suited for dealing with
copper based tubing. Acetic acid (vinegar) is generally not recommended for
I wonder if that machine ever was de-scaled or cleaned during its time in
service. They guy I bought it from did not have the water softening cylinder
that WMF ships with the machine by default. The water dispersion plate below
the shower screen was so strongly glued to the group head with coffee
residue, it took three runs with a coffee cleaner to get it off. It really
helped to use a little pipe brush to clean the insides of the brew head, I
could still extract coffee remains after the three coffee cleaner runs.
Getting new seals and gaskets should be easy. Unfortunately it seems to be
particularly hard or expensive to get technical information on the machine. I
paid 10€ (plus 10€ UPS COD) for 5 photocopies/prints of the machine
sketches with spare parts numbers but no textual description that I received
from the local Cimbali dealer.
Other manufacturers have complete spare parts listings and machine
Thankfully, there are helpful people online, a big thanks! You know who you
I sketched my own hydraulics
diagram as a reference.
For the 1/8" connectors around the pump and the water inlet I used Loctite
542 as Teflon tape will not allow you even the slightest readjustment...
Even after cleanup, the pump would not work, looks like the coils where
fused, so I started looking around for a new pump. There are not too many 24V
vibe pumps available. I ended up ordering a 48W Fluidotech after some
research. The ULKA would have been cheaper, but the Fluidotechs are built for
continuous operation whereas the ULKAs will die if run for too long. In
addition, the Fluidotech has a higher flow rate, not on par with a
rotary, but higher than the ULKAs. Of course, I also considered a
rotary, but apart from one online suggestion without any hints on how to
really do it everyone I asked said don't do it, too much of a hassle. After
having read the
comparison of two Cimbali Juniors, one with vibe and one with rotary that
produced indistinguishable shots in blind testing, I figured it is not worth
the hassle and money to go for a rotary.
Of course I am vain, so I bought new style Cimbali handles for the
portafilters. They look and feel so much better than the old ones ;-}
I also bought the current Cimbali baskets. Much bigger than the old
ones, especially the 1 shot basket.
A new steam wand is on order. From the third party suppliers it is not
really clear which one to order for this machine, but that will be solved
pretty soon I hope.
Initally I had a third party square brew gasket. Since I switched to the
conical original Cimbali gasket, the machine is less prone to leak at
the brew gasket and it takes less force to tighten it.
Was it worth the hassle
That depends on your point of view. After one week, the machine seems to be
more picky than the Oscar and the results are not noticeable better when
it comes to espresso. Steaming on the other hand is faster and easier than
on the Oscar. The chrome "three holes around one center hole" Cimbali
steam tip is great.
I'll write more once I had enough time to really become familiar with the
machine. One thing that is surely different from a tank machine is the
influence of the cold water that comes in once the HX and the internal
piping has been completely replaced with fresh cool line water.
The baskets knock out a bit cleaner than the La Marzzocco baskets that I
have been using on the Oscar.
Having a system connected to the water line and drain is a
huge convenience factor!
Not having to listen to the vibe pump filling the boiler when the timer
comes on in the morning is also a really big plus.
- Boiler insulation
- Whereas newer Cimbalis have it, all the old ones have naked boilers,
producng lot's of waste heat (the heater switches on for 8s every minute
at the moment). I was thinking about glasswool wrapped in
aluminium foil, but gave up on the idea, I think it is too messy. Right
now I am trying to find the insulation material that is used in solar
heating system. This is supposed to withstand much higher than boiler
- Bottomless PF
- I played with a borrowed bottomless PF for a while. Great. I want
one too. It is so much easier to see tamping/packing errors. And it
gives me more crema to mix in with the milk.
- Boiler drain valve
- Currently the lowest boiler opening is just blocked by a screw. That
should be easily replaceable by a drain valve even though the parts list
doesn't show one. Other Cimbalis have it, so it should be easy to find it.
That valve could then be connected to the drain, making it easy to
completely drain the boiler.
- Heater control lamp
- Currently the machine only shows that it's on and when it is getting
new water into the boiler. I would like to have an indication of the
heating element working as well.
Are there any dual lights available that would fit where the power light is?
- Yeah, I know it sounds crazy to PID a Cimbali, but that would allow me
to easily adjust the temperature for different roasts vs. opening up the
side panel and, turning the presostat screw and hoping I hit the right
amount the first time.
|Total boiler capacity
|Nominal boiler water capacity
||24V Ulka vibration pump
||24V Fluidotech "mono" vibration pump,
Manufacturers and parts suppliers
Espresso related web sites
Other machine restauration projects
© Andreas Siegert 2004
Last modified: Fri Oct 1 23:00:28 CEST 2004