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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

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.)

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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

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

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.

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.

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.

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.

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...

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.

TIPS AND TRICKS

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.

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.