Gaggia Classic Disassembly and Cleaning

I recently purchased a used Gaggia Classic machine on Amazon. After realizing that it was not as “lightly used” as the seller denoted, I took apart the entire machine to clean it up. I’ve written this guide as a teardown guide, but feel free to read it from bottom-up to get a clear understanding of how to assemble this machine. Feel free to drop a comment if you have any questions or information to add.

Tools

Before you start out, I would recommend purchasing a few tools (most available at your local hardware store):

Note: You can buy citric acid at many bulk food stores for a reasonable price

Remove the Boiler

Begin by removing the two attachment screws on the top of the machine by the water spout. The top plastic water spout / sheet metal assembly should pull off towards the back of the machine.

Next, pull the steam wand knob off (it might take a bit of effort). Note that the valve in the photo above is a bit offset, this is due to my machine being damaged. Yours should (hopefully) be centered in the hole. You’ll also want to pull the push-on connectors off of the power connector on the rear of the machine, and pull all the cables off of the front switch. I recommend numbering each of these connectors before pulling them off so you can easily reconnect them.

Flip the machine over and use allen wrenches to remove the four bolts attaching the group to the chassis.

After removing these screws, your boiler should be free. Remove the boiler from the chassis and place it in a clean work area. Note that things might get messy and/or moist very soon.

Using a standard or crescent wrench, remove the chromed steam wand from the copper steam pipe. This will allow you to set the group down on a flat surface without damaging the copper pipe.

Next, detach the electronics and pump from the machine. You will need to detach the pump hose from the OPV and unplug all push-on connectors. If you leave your wire assembly as-is after you unplug all connectors (don’t bend or crush the wires!) you should be able to easily see where all of the wires connected to for reassembly.

To make life easier, remove all hoses from the machine. You should only need to remove the 3-way solenoid hose and the OPV hose at this point.

Now flip the boiler on its side. You’ll see a phillips screw head in the middle of the shower screen.

Remove the phillips screw from the shower screen, and then pull off the shower screen itself. If it is stuck due to calcification or coagulated coffee compounds, use a small flathead screwdriver to pry it off.

Now grab an allen wrench and take off the metal block that resides under the shower head. You should now be able to see the top of the group.

Using a plastic spudge, flathead screwdriver, or even your fingernails, carefully pry up the rubber gasket from inside the group.

Now flip your boiler assembly back up on end.

Using a wrench, remove the steel nut from the top of the solenoid valve. The black solenoid coil should slide off freely. Next, unscrew both of the thermal switches from the top and the side of the boiler. The high temperature switch goes on top, and the low temperature (brew) thermal switch goes on the right side of the boiler.

Now remove the solenoid valve assembly from the boiler using an allen wrench. You might want to take out the rubber o-rings for cleaning if they are badly calcified.

At this point you can unscrew the hose fitting on the top of the OPV. This is most easily done when the assembly is still attached to the boiler.

Now unscrew the entire OPV assembly from the boiler. Once again, you might want to remove the rubber o-rings for cleaning if they are looking shabby.

Now is the time to remove the steam valve. This step can be a bit tricky, especially if your machine is older. I recommend removing the two bolts and twisting the valve back and forth. After some twisting, use a flathead screwdriver to carefully pry each side of the valve until it comes free. Don’t be too aggressive, as brass is a soft metal. You’ll probably want to remove the rubber gasket as well, mine was very calcified.

Next, remove the four bolts attaching your boiler to your group, and your machine should be fully disassembled! You’ll want to remove the rubber gasket from its slot in the group, if you have an older machine this gasket and its slot will definitely need some cleaning.

Cleaning

Your boiler probably looks something like the photo above and/or it might look white with calcification. Pretty nasty. If you have a lot of white calcification, a brass brush (available at most hardware stores) will take care of it. If you have a lot of oxidation and black residue like I had, a dremel tool with a stainless steel brush attachment will get the job done.

Above is my boiler after significant dremeling and brass-brushing. It’s not great, but it’s good enough for me. Although the aluminum around the seal is very pitted, I haven’t experienced any leaks whatsoever.

To clean the rest of your components, I recommend soaking them in a solution of citric acid or special-purpose espresso machine cleaning solution (available at many online retailers). This will remove significant amounts of calcification.

If your machine is as old as mine, you might need to do some more intensive cleaning. Try using a brass brush with your citric acid or espresso machine cleaner solution. Use the brush to clean off brass fittings (especially the steam valve fitting), the group, and any other metal components. This should take off any lingering calcification or other gunk.

Now that you’ve cleaned everything up, it’s time to put things back together! If you need additional help, just read this guide backwards to get a good idea of how to re-assemble machine.

Has this guide helped you out? Spare a few pennies and feed a poor college student!

Ethan is a computer engineer and open source hardware/software developer from Michigan. He enjoys AVR and linux development, photography, mountain biking, and drinking significant amounts of home-roasted coffee. Find out more at ethanzonca.com.

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31 comments on “Gaggia Classic Disassembly and Cleaning
  1. Marcus says:

    Cool — Thanks for posting this!

  2. marius says:

    Nice job !

  3. Oliver says:

    I think the pitting may indicate it was cleaned with vinegar, which I think I read reacts with aluminum. The boiler of my old machine became much more leaky after I ran vinegar through the system–to the point that I sold it cheap to someone interested in rehabilitating it.

  4. Very neat and clean images that made me understood very well. Thanks for sharing this. I am gonna try it soon.

  5. Rory says:

    Hi Ethan,

    I serviced my Gaggia Classic today using only your guide for assistance. I’m glad to say it went swimmingly. I replaced all seals (the boiler seal had been leaking) and cleaned the insides using a Dremel + wire brush attachment. The only thing I failed with was removing the steam valve. I just couldn’t get it to budge at all. Regardless, the machine is now working much better than before and is clean inside and out.

    I just wanted to say thanks for taking the time to put up this excellent guide.

    – Rory

  6. james wallace says:

    Things should improve with Gaggia’s new descaling instructions, using only the steam valve and turning the machine off while the chemicals do their work. This means it is virtually a cold (or lukewarm) process rather than their previous instructions which had the heating elements switched on throughout the whole process. Best wishes, James

  7. Rik says:

    Great pics and description Ethan.

    Thanks. It’s a fairly simple job but that doesn’t mean it isn’t a hell of a lot easier to do with a resource like yours.

    My machine was well overdue for a strip down and it is so badly corroded inside the boiler that it makes your’s look like it just got shipped from factory to showroom.

    Right now I have the “metal block that resides under the shower head*” sitting in WD40 in the hope that a hugely stubborn Allen Bolt will come off tomorrow. It’s one off two pieces that won’t break away. The OPV assembly wpon’t come off from the boiler either.

    (*the block which needs taking off in order “to see the top of the group”)

    In the meantime I have just one question.

    You say we will “want to remove the rubber gasket from its slot in the group, if you have an older machine this gasket and its slot will definitely need some cleaning”

    I don’t want to remove it unless I can find a replacement. It looks like it’ll fall apart if I try to move it. Any ideas re where to find a replacement gasket?

    Rik, Sydney, Australia

    • Hey Rik, there are actually a couple sites selling replacement parts for the Classic since it’s such a popular machine. Check out partsguru, they sell pretty much any part you might need. Good luck with your stuck allen bolt!

    • Craig says:

      Hi Rik,

      This thread’s a little old, but just in case… I’ve been able to all my Classic parts from http://dibartoli.com.au/ in Bondi Junction. All by mail, but they probably do walk-ins as well.

      Cheers

  8. Rik says:

    Thanks for the info. One other thing I’d like to know is if you or anyone knows if non-aluminium boilers are available for this or other home espresso machines.
    Frankly I’m a little disturbed by how much aluminium has eroded and doubtless made it into my diet. Big pits and holes.

  9. Steph says:

    This is a great explanation but I am totally at a loss with taking things apart. I have regularly de-scaled my machine and recently took apart the group head and replaced the rubber seal with a brand new one but for some reason water does not appear to be going up the tubes into the machine…the pump makes the usual sound but not a drip of water anywhere! I am hoping that it is something really simple as beginning to get demented! Any help would be gratefully received, I have had my machine for over a couple of years…missing my coffee :-(

    • Peter Brannon says:

      Hi Mick,

      I did the complete strip down (twice) to no avail. After more research I checked the continuity on the solenoid which indicated it had failed so I found a replacememt on the internet and installed it. (Lesson learned ?….. Check the solenoid first ! )

      The flow through the brewhead was now magically restored to normal, but my steam had mysteriously and annoyingly disappeared! After a bit more research I replaced the steam thermostat. Now everything is back to normal (except a previously non existing noise has developed, like the braying of a demented donkey followed by noisy rapid bubbling just before the steam light comes on. Any thoughts on this from the experts ?)

      Anyway, I don’t regret doing the strip down as it familiarised me with my machines inner mysteries, and at least I know it’s clean!

      Good luck with your problem. I can forward the solenoid suppliers details if you need them.

      Regards

    • DDutch says:

      You’ve probably solved the problem by now but it seems the 3-way valve in your machine is stuck. This is the little black box connected to the bottem of the boiler. Take it off and try to disassemble it as far as possible and make a note or take photos, so you know exactly where all the parts belong. Be careful, there are some very tiny parts inside. You can clean them with warm water en let them soak in a bit of Gaggia descaler for an hour. Clean them again and reassembly. Your machine should give water again, at least through the steam valve.

  10. Peter Brannon says:

    I would be very grateful for any advice you could offer.

    My two year old classic (which has been descaled regularly) produces hot water and steam through the wand but not through the brew head. I followed the guide on another site to remove and clean the solenoid, (which had no signs of scale). Unfortunately this has not solved the problem.

    I am considering following your excellent guide to completely strip and clean my machine. Do you have any other suggestions before I do that ?

    many thanks for your time.

    • Mick Hough says:

      Peter – I’m in the same position. Having taken both the brew head assembly and the solenoid off, and given them a thorough clean, it hasn’t solved the problem. Did you have any replies about what to do next, other than a complete strip-down? I’m planning to have another go with some descaling chemical before going any further. Any advice welcomed!

  11. Craig says:

    Hi Ethan,

    Awesome post, thank you. My machine has an issue where there’s basically no water coming through the group head. I’ve put a new pump in but apart from being remarkably quieter there’s no difference. On the picture labelled ‘group head’, the copper(?brass?) pipe that comes through, is that supposed to be clear? Apart from that do you have any ideas? Really appreciate any advice!

    • If you think that the pipe might be clogged, definitely run a pipe cleaner or brush through it! You can try blowing air through it to see if it is completely blocked (it is routed to the slightly copper-stained hole on the side of the group in that photo, if I remember correctly).

  12. Duncan says:

    What a fantastic website! I just fixed my problem with some hardcore limescale remover (old school with wine vinegar), but I’m sure at some point in the next 10 years I’ll be turning back to this. Brilliant, brilliant blog!

  13. Lynn says:

    Wondering if you might be able to help me-machine is only 3 months old and des caled twice. Group head only drips water. Cleaned shower screen and removed group head to clean. Looked inside machine at connections, hoses etc. all looks great and brand new. Steam and hot water work fine. Have primed it several times. Thoughts?

    • Craig says:

      I had much the same problem Lynn, (although it took me a lot longer than 3 months to get there!) turned out that the shower plate (not the screen, but the metal block it’s screwed into) was blocked. I took that off and cleaned it and all’s well.

      That’s the short answer, full version is that firstly the plate was very hard to get off. (about 9th pic down, “Now grab an allen wrench and take off the metal block that resides under the shower head. You should now be able to see the top of the group.”) Found a tip on another website that if you find a screw that’s the same as the one that holds the shower screen on but longer, screw that in and keep going it will dislodge. Cleaning was another matter all together. Tried all sorts of things but the ‘gunk’ was baked solid. Used a Dremel (actually a Ryobi, but same thing) with a wire brush attachment to get rid of it all. There’s 4 small holes in this plate that the water comes through and it doesn’t take much to block them or the flow to them.

      Good luck!

  14. Makoto Takashina says:

    Hi, Ethan, My Gaggia Classic looks different from your pics, but anyway, someone stupid put coffee into the water tank and ran it while I was not home. As a result coffee clogged the plastic tube. I can see coffee in the tube trying to get through. I was able to remove one end of the the tube which was screwed in with metal piece, but cannot remove other end, which seems welded (?). So, I cannot clean it. Any suggestion? Is it worth to struggle, because coffee may have been already deep into the system beyond the tube already.

    • Hmm, you might be able to get a pipe cleaner or drain snake down the pipe and pull some of the gunk out. If you have an ultrasonic cleaner, that might work as well. Good luck!

  15. Michael Nugent says:

    After looking at my broken Gaggia Classic on the kitchen counter for two years and after one failed attempt, I decided to repair it over a holiday weekend. Your article was absolutely invaluable and guided me all the way. I had to supplement the main washer at the bottle of the boiler with a very thin plastic addition. Now it’s fully back in action! Cheers – Michael (Dublin, Ireland)

  16. Gnev Zmaja says:

    Great and detailed post, thank you for your effort, if I haven’t ran across this article I would never got involved in dissembling this machine…now I’m glad I did it…Just to add one thing that might help someone not so experienced in wiring and electricity. Before disconnecting wires from the front panel switch block I took a picture so I can work out wire coloring to connect them back afterwards…this haven’t seemed to be enough information though…blue wires were not all at the same voltage (contrary to my logic) so when I connected them back switch block was working improperly…so take care of the blue wires, follow the one which comes from AC and take note of the remaining two blue wires and mark their switch connectors properly before disconnecting. Another wiring confusion that can arouse are heater(boiler) contacts (3 black and one yellow wires are connected to four pin connectors) This is in fact two resistors connected in series as two of the black wires are same wire(short circuit) Mark this wire and make sure that you don’t short circuit same heater (which could happen if you follow only wire color logic) as this will result in having all the voltage on one heater and other one off the power. Cheers from Belgrade, Serbia

  17. Fouad Brikci says:

    Fantastic informations.
    Just to tell you : Thank you
    From Montreal, Quebec Canada

  18. cheng li says:

    Hi Ethan,
    Yesterday my Gaggia was having trouble, little water was pouring, and at the end of the day there was almost no water was coming out.
    It was obvious something was blocking the head, because the milk steamer didn’t had any problems with the water.

    I’ve followed your steps and disassembled and assembled the Gaggia Classic, but when attached on the power it allways short circuits. I have googled and read the same thing happened to another person
    http://coffeesnobs.com.au/brewing-equipment-midrange-500-1500/34645-gaggia-classic-electrical-issue.html

    Here he mentions the problem is with the boiler element. I know from my experience with my Whirlpool oven that if the heating elements get wet (happens when you don’t use the oven for three months) this will short circuits the ground in my house.

    The solution is to temporary break the ground line on the 220V power, switch on the machine and heat up the boiler until the heating element becomes dry. (1 hour will do it).
    Then you can attach the ground again on the 220V.

    Problem is fixed and my Gaggia is working good! Thanks for the info.

    Sorry for my poor English, if I make any grammar errors, please forgive me.

  19. Colin M Baker says:

    Hi, If the plate that the spray plate screws onto is well and truly corroded like mine was, turn the (empty) machine upside down, remove the spray plate and the 2 Allen screws and use a plastic hypodermic syringe to inject citric acid mixture into the holes and be patient, leave the machine for at least an hour to break down the lime scale inside. You may need to add more solution during this time to keep the holes filled.
    Then get a long 5mm machine screw and screw into the shower plate fixing hole and it will jack the back plate away from the brew head. Be patient, if at first it doesn’t come free, let it soak a bit longer. It does work.
    Very useful article, many thanks.

  20. Steven says:

    I’ve done all of this a few times but there’s one step I can’t accomplish:

    “Now grab an allen wrench and take off the metal block that resides under the shower head. You should now be able to see the top of the group.”

    That metal block may as well be sealed on. The allan bolts come out easily but the peice they secure seems permanently stuck on. I suspect the only reason I can’t pump water through the group head anymore is due to calcification between these parts. The rest of the parts are clean.

    Any advice?

    Currently I’m resigned to selling it for parts (let me know if you’re interested), since the rest of it is in good working order and I replaced the pump last year with one that has brass fittings.

  21. Steven says:

    I can’t get the metal peice off the group. The allan bolts come out easily, but the metal peice seems like its sealed on. Any tips?

    • Colin M Baker says:

      See my posting about stuck plates, inject citric acid descaler into the bolt holes (with the machine upside down) and leave to soak for at least an hour, then put a long thread 5mm screw into the shower plate hole and carefully turn it to force the plate out. If it won’t come easily, leave it to soak for longer. Keep the solution topped up. It does work, but may take some time.

  22. Andy Kay says:

    It might be worth mentioning that you would want to let the whole machine fully cool down before stripping it. Mine was still warm in places and I think that’s why my High Temperature switch screw snapped while I was unscrewing – meaning I have to buy a new boiler and switch.
    Also even if the group head is stuck – do not use WD40 – you wont be able to remove the lubricant from the metal parts and your coffees will have a slight taste to them for a long time!

2 Pings/Trackbacks for "Gaggia Classic Disassembly and Cleaning"
  1. [...] The bubbling in the water tank is the over pressure valve releasing the built up pressure, because you obviously have a blockage somewhere in the group assembly, most likely from, as you mentioned you live in an area with fairly hard water and lots of calcium which requires much regular de-scaling or a good water filter. It does not take much to block up any number of small holes. If you have mechanical aptitude these machines are really very easy to work on. They are built like old cars, fairly simple to identify parts, lots of space and built to last, so very serviceable. If not you should just take it to a coffee machine service tech. If that was my machine i would strip it down to bare parts, clean everything and reassemble then reassess the situation from there. This is a decent pictorial. Gaggia Classic Disassembly and Cleaning | [protofusion] [...]

  2. […] Ethan Zonca runs through taking apart a Gaggia Classic […]

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