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Domestic Espresso Machine
Repair
Repairing domestic
espresso machines is an activity that can be separated
into 5
distinct phases:
1) Diagnosis
2) Disassembly
3) Repair
4) Testing
5) Reassembly
Diagnosing the initial problem can be something
of an art, but the block
diagram should help with some of the
basic problems. Once the diagnosis is
reasonably certain, the
disassembly phase can begin.
At this point it's wise to note that certain
machines (mostly thermoblock
machines made in China) are
designed NOT to be disassembled by the
layman. If there are
special screws or bolts, if the fasteners are concealed, if
the
body is glued or clipped together with internal fasteners, it's
fairly certain
that the manufacturer doesn't want you poking
around inside. These
machines usually come with "Replacement"
warranties, i.e. you send them
back to the manufacturer and they
ship you a new one and scrap the dud.
In this article I'll concentrate on 2 machines I
sell, mostly because I've had a
lot of experience in tearing
them apart and putting them back together again.
However, the
principles of what I do can be generalized to suit many other
types of machines.
One important rule with all repairs concerns the
electronic connections,
particularly those for the
various electronic bits like switches, thermostats, solenoids
etc. NEVER
LEAVE THEM DISCONNECTED. If you
have to take the wires off to
remove the thermostat, reconnect
them to the thermostat as soon as it's
removed. Any time
that a wire will be disconnected for longer than a couple
of
seconds, TAKE A PHOTO so you know exactly where and how it
reconnects.
Plumbing connections tend to more forgiving
(there's usually only one way to
connect them) but Teflon tape,
thread sealant and high temperature silicone
gasket sealant are
proven methods for preventing inconvenient leaks.
IMPORTANT
DISCLAIMER!!! ANY REPAIR WORK ON MACHINES SHOULD ONLY BE CARRIED OUT
WITH THE MACHINE DISCONNECTED FROM ELECTRICAL POWER AND THE BOILER
COLD. IF YOU IGNORE THIS AND DAMAGE YOURSELF, DON'T COMPLAIN TO ME;
YOU'VE BEEN WARNED!
RANCILIO SILVIA
The first thing you need is a reasonably comprehensive
tool kit. Note that (apart from the "weird bits" set)
there are no really specialised tools involved, just metric spanners,
metric sockets, screwdrivers, pliers, wrenches and a
hammer.
GENERAL MACHINE
ACCESS
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| UNPLUG THE MACHINE!
Remove the water tank and unscrew the 4 screws. Remove the top
panel. |
Undo the 2 small screws (fine pointed phillips head
screwdriver needed.) |
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Looking down into the tank area, a screw is visible in the
cutout slot. Unscrew this a couple of turns, then slide off
the rear panel. |
Undo the 2 screws and washers (DO NOT LOSE THE WASHERS) and
remove the interior
panel. |
BOILER REPLACEMENT
When to do it?
When your boiler either won't heat up, or you're getting circuit
breaker trips due to current leakage. Element continuity can be
checked with a multi meter; if there's no continuity, you need a new
boiler. A leak around the base of the boiler (perished boiler
o-ring) can be fixed using the same basic steps.
Parts needed:
New Boiler, Boiler o-ring, spacer washers.
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| You now have complete
access to the innards of your machine. This is the latest
Silvia, the rest of the photos are
of the older model, which most people have. |
Begin by removing
the thermostats and element leads. The overtemperature (red
button) thermostat unscrews out of the body of the
boiler. |
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| Then undo the
steam pipe nut (18mm) where it attaches to the
boiler. |
Next is the 12mm
compression nut which attaches the teflon pipe from the pump
to the boiler. |
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| MAJOR
TIP: When pulling or pushing teflon tube, use a piece of fine
sandpaper or a scotchbrite pad for grip.
Pull the tube off the nipple
then undo the hex bolts from the boiler. The longest bolt
(with washer) is the one the earth wires attach to. |
In a sink or
tray, knock the boiler loose with a sharp tap with a hammer,
then pull it straight up. Clean up the base, remove and
discard the old o-ring, insert a new o-ring in the groove.
Note that all the crap in the base is a consequence of boiler
overheating. |
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| Remove the overpressure
valve (OPV) hose from the old boiler (don't lose
the spring clip.) Give the bolt (left hand) end of the valve
(NOT the barb) a sharp downwards tap with the hammer,
then unscrew the OPV. |
Now comes the
most difficult part of the whole process. Inside the OPV there
may be a copper compression spacer washer or two, or three. Even if there isn't,
you might need a combo of thick and thin washers to get the
OPV TIGHT, in the correct position, on the new
boiler. |
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MAJOR TIP: Play with various washer
combinations until you can screw the valve up TIGHT in the
correct position.Once the washers
are right, I anoint the threads with pipe sealant, then use
10cm of teflon tape on top of the sealant. |
Then it's a matter of
screwing on the OPV until it's good and tight in the correct
position, an upside down V. Doesn't
have to be exact, but if anything the right hand side should be
a fraction lower than the picture. |
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Before reassembling I run a bead of
high temperature silicone gasket sealant around the edge of
the boiler as "insurance" against leaks. Attach the OPV hose
before putting the boiler back into the
machine. |
Finally, I trim 5mm off the
end of the teflon pipe before pushing it back onto the nipple (you can
only do it once), then reassemble everything in the order I removed it.
Make sure all the boiler hex bolts are good and
tight. |
MAJOR TIP: DO
NOT OVERTIGHTEN THE OVERTEMPERATURE THERMOSTAT OR THE TOP
THERMOSTATS' BRACKET SCREWS. Otherwise they'll break off in the
boiler body and you'll be in all sorts of trouble. As tight as you
can get with 2 fingers on the screwdriver or socket is
enough.
MAJOR TIP: TEST
THE MACHINE FOR LEAKS ETC. BEFORE PUTTING THE PANELS BACK. IT'S MUCH
EASIER TO FIX STUFF AT THIS STAGE.
STEAM VALVE
RENOVATION
When to do it?
When you're getting water leaking from the steam wand itself
(washer) or along the shaft (o-rings) or down the length of the wand
(o-ring.)
Parts needed: Steam valve washer, 3
O-rings.
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| Remove the steam
valve knob by pulling it out from the machine. |
Undo the steam
wand nut (18mm spanner) and remove the wand by pulling it
down. The o-ring may be on the end. |
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| Undo the
connecting nut (17mm socket). If the o-ring wasn't on the end
of the wand, it will still be inside this nut. Remove
it. |
Undo the boiler
connecting pipe (18mm spanner) then the locknut. Remove the
steam valve from the machine. |
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| You now have to
undo the stainless steel bit from the brass part of the valve.
I find it easiest to lock the brass bit in a vice
first. |
The shaft can
then be screwed out and the o-rings & washer replaced.
Note that the washer is held on by a little
bolt. |
Reassemble and replace everything
in the order you removed it. MAJOR TIPS: Screw the shaft out as far as possible
before tightening the stainless steel bit as much as possible. Put
the o-ring on the end of the steam wand before pushing it into the
connecting nut. Tighten the brass locknut as much as possible before
doing up the steam pipe.
SOLENOID VALVE
REPAIR
When to do it?
When the solenoid valve leaks during brewing, usually accompanied by
a "pipe hammering" effect. (Cleaning required.) When water will
flow from the steam wand, but not the group.(Coil
replacement.)
Parts needed:
o-rings (rare), solenoid coil. Very rarely a whole new assembly is
needed.
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Undo the two
screws and slide the front panel out to the right. This gives
you complete access to the solenoid valve
assembly. |
Undo the spout, then the coil retaining
nut. |
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| At this point the coil can be removed by simply
pulling it down off the valve shaft. If it needs replacement,
it's a simple matter to pull the existing electrical wires off
the old coil and attach them to the new one, one at a
time. |
If the problem is grit in the valve, it can be
unscrewed at this point and removed for cleaning. |
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| The slug and spring come out for cleaning. They
will only fit back in one way, making reassembly
easy. |
If there is a problem further upsteam in the
valve, the rest of the body can be removed by undoing 2 hex
nuts (in older models, flat head screws) and removing it from
the group assembly. |
COMMONLY AVAILABLE SPARE PARTS
LIST.
The Silvia has been constructed using in many cases
"commercial" parts from Rancilio's other machines. This means that
commercial parts suppliers can often have just the bit you
need, which can be especially helpful if you don't have ready
access to an authorized Rancilio dealer. In Australia
the best online parts supplier is www.coffeeparts.com , and I have
supplied their parts numbers for the commonly available bits
below.
700151 Group Gasket
700347 Water
Distributor
700164 Shower Screen
700326
Showerscreen Bolt
700299 Portafilter
511673
Portafilter Spouts
700179-22 Solenoid Coil (Brasilia Page
1)
700177 Solenoid Valve (Brasilia Page 1)
524767 Solenoid
Valve o-rings (Brasila Page 1)
617160-22 Ulka Pump
LELIT PL042 COMBI
Most of the steps outlined below
apply to machines from Imat, Nemox and Lelit, as well as obvious
rebadges such as the LaPavoni Napoletana. I have concentrated on the
models with 3-way solenoid valves as they are the most
complex.
SPECIAL TOOLS
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| There are 2
indispensable "special" tools needed for this class
of machines. The first is an 8mm socket with the outside edge
ground down sufficiently to give access to the group collar
nuts. |
The second
tool is a 14mm ring spanner ground flat so that it can undo
the thin, soft edged brass water distribution nut and
allow showerscreen removal. (Note that showerscreen types and
fixtures may change from machine to machine, and the current
Lelit machines don't have this screen and nut
combo.) |
GENERAL MACHINE
ACCESS
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| Getting in to the machines is simple, there are
only 2 small phillips head screws to be removed. One is behind
the grinder hopper .. |
..and the other at the corner of the water tank recess. The
whole top then lifts off. You'll have to remove the filter on
the end of the inlet hose to free the
hoses. |
ELEMENT REPLACEMENT
STEAM VALVE
RENOVATION
SOLENOID VALVE
REPAIR
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| Unlike the
Silvia, this is as good as it gets for access to the internals
in these machines. In order to fix stuff like the element,
solenoid or some bits of the steam valve, you have to remove
the boiler first. |
The first step in
removing the boiler is freeing the indicator light,
accomplished by pressing a finger on the little orange cover
on the machine's front, then pulling the light away from the
cover. |
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| Then using a
15mm spanner undo the split retaining nut on the steam valve
until you can slide it free of the shaft. |
The shaft can
then be unscrewed and removed through the front of the
machine. Stuff like o-ring replacement or shaft touch up can
be done at this stage. |
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| Next step is
removal of the wiring; the thermostats unscrew. Remember to
reconnect and/or label and photograph as you go along. Remove
the wiring and outlet hose from the solenoid valve as
well. |
Then undo the
water inlet hose (12mm spanner.) Most machines have this brass
nut and ferrule arrangement. Do NOT try grasping the hose with
pliers, use sandpaper or a scotchbrite pad. |
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| It's easier on
the latest Lelit machines. With these fittings you simple
depress the green plastic ring and pull the hose out of the
fitting, and replacement is accomplished by simply pushing the
hose back into the fitting. |
At this stage you undo the group collar nuts and remove the
group collar. The whole boiler, steam arm and solenoid
assembly can then be lifted clear of the machine. This is the
point where the steam arm o-ring and the solenoid coil and
valve can be removed and replaced. |
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| Now comes the
tricky part. The water flow through this boiler to the group
goes >>boiler input>>steam
assembly>>solenoid valve>>teflon
pipe>>copper pipe>>water distributor. First undo
the 10mm compression nut and remove the pipe from the
nipple. |
Then unscrew the 12mm nipple nut from the top of the copper pipe
through the boiler. Do not damage the thread or lose the
o-ring... |
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| Now you can
undo the 4x8mm boiler bolts and separate the halves. |
At this point things are
easy; you can replace the element, replace the boiler o-ring,
whatever. The reassembly goes in reverse order, but with the
addition of a little bit of silicone at the top of the copper
pipe, and around the element and boiler o-rings. And make sure
that the group collar is on the right way before doing up the
nuts. MAJOR TIP: Don't Forget to push the
solenoid drain tube back onto the nipple before testing the
machine.
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TIPS AND
TRICKS
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| The steam valves on these machines are needle
valves, and tend to wear as the machines age. Filing about
0.1mm of brass from the flat seat about 1cm from the needle
tip allows the valve to do up a tiny bit further and
compensates for wear. |
Removing stuck showerscreens can be a pain, but
removal can be helped by using a hammer and flat head
screwdriver at the edge of the screen to "chisel" it in the
anticlockwise direction. When the screen begins to rotate
you should be able to undo the screw. |
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| Sometimes the showerscreen is so dirty no amount
of detergent or scrubbing will clean it. Heating it to red hot
over a gas flame burns away the crud clogging the holes
quickly and effectively. |
The quickest way to remove old group gaskets
from any machine is to screw a couple of self tapping
woodscrews into them and pull the screws out with pliers. Even
if the gasket comes out in chunks it gives you a chance
to chisel out the rest. | |
