Santiago Senior Member Joined: 8 Aug 2003 Posts: 10 Location: Melbourne (Australia) Expertise: Professional
Posted Fri Oct 3, 2003, 8:34pm Subject: How to overhaul your Gaggia
I have just completely overhauled an old coffee Gaggia. It now operates like a brand new one. It had never been seviced. the scale inside the boiler walls was 3mm thick and some pretty severe corrosion had taken place, it leaked like a sieve, heated slowly and it was producing a "rancid cup". Here's how I did it: First throw out the useless crema disk and plastic steam stupid thing. Tools: >Dremel with flexy hand piece & steel wire brush attachment >sockets spanners, screwdrivers and metric hex key set. >6 sheets of water proof sandpaper, ranging from 220-800 grit. >WD-40 >replacement group seal, boiler/group o-ring, spring and ball seal, 2 0-rings for steam wand needle valve and any other seal or o-rings you care to replace. Method: 1-Unplug it. Remove the top cover. Dissconnect wires, labeling them as you go and tape them out of the way. 2-With 13mm spanner disconnect braided water hose from top of group. 3-Use 4mm hex key to remove retaining screws from around group head (underside). 4-pull steam knob off. Carefully pull boiler and group head assembly out of machine casing (you may need to remove steam wand). 5-With the grouphead and boiler assembly out of the machine, remove the steam wand (if you didn't already). 6-Give a good dose of WD-40 or some other penetrating lubricant to the hex bolts that hold the boiler to the group head. If you can wait over night all the better. I didn't and ended up shearing one off and having to drill it and use a screw extractor to remove the remaining bolt - your choice. 7-Once you've removed the boiler from the group head you'll see what your in for. I started on the boiler first. Basically you want to remove the scale and resurface the flange or the bottom of the boiler where it seals to the group head. The one I did was so pitted and corroded it would never seal again properly without resurfacing. You could take it to a machine shop and have the guys plane it off a bit, but I settled for a flat surface, sand paper and elbow grease. If you use sand paper, use water proof and have a bucket of water on hand. 8- Start with 220 grit, wet it and put it on a flat surface. Start sanding, keeping the paper still with one hand and making figure 8 movements with the boiler in the other hand, keeping the flange flat against the surface. Rinse the paper frequently. Keep this up until all the pitting is gone. repeat the process with 320 grit paper, then 400, then finally 800 grit untill you have a very smooth, clean, flat surface. 9- Now it's time to de-scale the inside surface of the boiler. Remember that it's aluminium and soft. Avoid using burrs or anything too abrasive as it will easily cut too deep and damage the surface. Be most careful of the temperature sensing nodes protruding in from the top. I used a steel wire brush on the hand tool of a dremel and a light touch. Use gloves, dust mask and eye protection at all times. When your happy with that, then move on to the group head. clean up the steam wand needle valve and replace the seals if you wish. 10-Unscrew the shower screen and put it aside. you'll see two 5mm hex bolts. It's handy if you have a vise as these can be very tight as with all the others. Once removed, the aluminium disperser should come free. If it is stuck, screw an M5 screw into the shower screen screw hole which will push against the spring and ball valve retainer and should pull it free. 11-Once that is free you'll see a 16mm nut in the centre. a socket and ratchet should take it out. Be careful not to lose the spring and rubber seal that it is inside it (unless you have a replacement one). 11-Carefully prise the old main seal out of the group head. Mine was a common black one, but I hear blue ones are hard or impossible to get anymore. If it's blue, then see if you can get a new one before destroying the old one. 12- I just went ahead with the dremel at this point and cleaned up every surface on every part as best I could. Just getting rid of all the scale and other deposits until all the parts gleamed like new ones. Once your happy with the results, give it all a good rinse and soapy wash and rinse and rinse a bit more. 13- Group head assembly is the reverse of removal (don't forget the spring and rubber seal, i did and when i did a test run she sounded like a jet engine winding up!). Make sure all your surfaces are clean and dry. This is a good time to unblock the shower screen and screw it back in place. Prime & paint any rust if necessary. Replace any bolts that are really crappy looking. If you replace the bolts for joining the boiler to the group head, make a note of the length. New ones may need to be cut shorter. 15- Insert the replacement main seal for the group. Refit steam wand, needle valve and cam. 16- When bolting the boiler back on to the group head with the O-ring in place, bolt it down evenly in a star pattern like they way you do the head on your car. 17- You can flip the cup warmer plate if you wish. On the underside of mine it was brand spankin' and only required little polish to look like new. 18- Now with the boiler and group head together again, refit some of the lower, 'hard to get at' wires and carefully lower the the boiler and group assembly back into place. 19- Refit the braided water inlet hose to the top of the group head. 20- refit the rest of the remaining wires (hope you labeled them at the begining). 21- screw in the group/boiler retaining nuts. I added washers, which it didn't originally have. 22- refit the water filler and cup warmer. Refit the steam knob. 23- Clean up your basket filters and the inside of the porta filler. 24- Fill it up with water and plug it in for a test drive. Put a container under the group without the porta filler and put one under the steam. turn it on, run the pump and open the steam valve to flush it out. Do 2-3 full water reservoirs or a least untill you have clean hot water that has no odour to it. Your all done and ready to make a brew! Total cost: $25 Australian. Total time: 2 hours You can now use a de-scaling product regualrly and it will have some effect. In my opinion it was well worth the time and effort. Sure it's a cheap machine anyway. Some may say "why bother?". To me it's another machine back on the road pouring exellent cups of our favourite liquor and not adding to our already out of control landfills.
Posted Mon Oct 6, 2003, 10:15am Subject: Re: How to overhaul your Gaggia
I didn't see this Friday Night post and overhauled my Gaggia Coffee Sunday Afternoon. This is an excellent set of instructions. I didn't think of the idea of using a Dremmel for cleaning ...good idea. The dremmel wirebrushes I've seen are only about 1.25" long. How did you manage to reach all the way down to the bottom of the boiler ? For cleaning, I used:
Screwdriver tips (gently so as to remove scale only without scratching the soft aluminum)
Plastic Scouring pads (green)
Razor scraper and brass wire brush. ...the objective being to remove scale while minimizing scratches to the aluminum.
For the flat mating surface of the aluminum boiler, I first removed loose scale as much as possible with a razor scraper. Then I had a wide flat fine file which I used to gently file the surface -firmly holding it flat on the surface at all times. It worked perfectly.
Some additional comments on your steps (for others who might do this in the future): Step #1: I was able to leave almost all wires connected to the boiler, removing a total of only 4 connectors - two wires to the power-in and two to the pump. Step #21: The four screws that attach the boiler to the grouphead are metric capscrews. They corrode because they're steel and they attach the alminum boiler to the chrome-plated brass grouphead. I replaced them (a good hdwre store will have them) and wrapped the threads in Teflon Tape (plumbers pipe tape) to minimize corrosion and ensure that they'll be removable in the future.
Regarding the rubber seal between boiler and Grouphead; this is a standard rubber o-ring. It is a metric size and it's extremely unlikely that you'll be able to find it anywhere but from a Gaggia Parts source. You'll probably be able to re-assemble your unit using the old O-ring but it's probably better to have a new one on hand to be on the safe side as pitting/scaling on the aluminum can affect the o-ring.
Santiago Senior Member Joined: 8 Aug 2003 Posts: 10 Location: Melbourne (Australia) Expertise: Professional
Posted Mon Oct 6, 2003, 9:06pm Subject: Re: How to overhaul your Gaggia
A flexi drive hand piece is how I got all the way in the boiler. Looks a little like a dentists hand piece and is a standard Dremel accessory. It will be interesting to see whether the plumbers thread tape stands up to the high temperatures. I used Ti-Prep anti-seize compound. I think it has copper dust in it. It will handle higher temperatures than the machine can achieve. As for the o-ring, you must use a food grade o-ring. If you use a standard one, there is a possibility of poisoning yourself. Good to see someone else taking the time to overhaul their machine. Don't they they operate soooo much better?
onoscafe Senior Member Joined: 26 Feb 2003 Posts: 55 Location: Toronto Expertise: Professional
Espresso: Gaggia Classic Grinder: Gaggia MDF Drip: Pyrex percolator from '50's Roaster: buy vac pac beans from Italy
Posted Tue Oct 7, 2003, 1:29am Subject: Re: How to overhaul your Gaggia
After you remove the boiler from the casing, flip it upside down (with the steam valve still in) and pour a solution of citric acid and warm water. wait about fifteen to thirty minutes and rinse with warm water. you will be surprised how much scale will be removed. If there is scale build up remaining repeat the process and then remove the valve and clean the opening.
Posted Tue Oct 7, 2003, 9:07am Subject: Re: How to overhaul your Gaggia
What's the easiest way to buy citric acid locally?
Are you sure that citric acid causes no adverse reactions with the Aluminum ? ( i.e. reactions that might render the Aluminum unsuitable -even temporarily- for food preparation )
After you remove the boiler from the casing, flip it upside down (with the steam valve still in) and pour a solution of citric acid and warm water. wait about fifteen to thirty minutes and rinse with warm water. you will be surprised how much scale will be removed.
I'm currently replacing the o-ring in Gaggai boiler. You mentioned that a food grade o-ring must be used. I've spoken to a guy at a fitting specialist and he seem sure that all Nitrile o-rings are foodgrade and mentioned that all the local coffee machine repair people use o-rings from his shop. Can you let me know if the food grade o-rings you use are made from another compound other than nitrile.
morzh Senior Member Joined: 25 Nov 2003 Posts: 152 Location: NJ Expertise: I love coffee
Espresso: La Pavoni Europiccola... Grinder: Mazzer Mini
Posted Tue Aug 3, 2004, 6:16am Subject: Re: How to overhaul your Gaggia
I did this to my Gaggia Coffee a week ago.
Opened up the boiler and cleaned it well.
One thing you did not mention (or maybe you did but I missed it) - there is the copper tube inside the boiler, through which the hot water goes eventually into the PF. I found massive amount of sludge mixed with copper oxide etc inside this tube. It did not block it thoroughly but did present some obstacle, plus being of organic origin God only knows what was in it and what taste it would impart on my espresso.
I recommend the tube to be cleaned, at least with a Q-tip or a narrow brush with some baking soda or mild abrasive.
A question: since you did the full job you might have some ideas as to:
My Gaggia, before the cleaning and after it would barely push water through the spring-rubber ball valve. I excluded things like Pump (it is fine and develops enough pressure), ducts (every opening in the way of the water is clean) and so on. A hint: the problem is pronounced when the hot water is run through the grouphead; while it is still cold the flow is OK. Another hint: loosening the spring (not tightening the hex bolt that holds it by a thread or two) eliminates the problem: the water comes out fine and the quality of the espresso is also fine.
Would you think the rubber ball itself may expand from the temperature (being old: the shape and initial size are fine) and plug the opening so it impedes the flow even if proper pressure is developed by the pump? (the fact that the pressure is there is obvious from two signs: 1. The water if the steam knob is opened, squirts really strongly, reflecting from a cup's bottom all over the place and 2. The pump would start spitting water from the safety valve back to the water tank).
As I said when the hex bolt is loosened, it fixes it all and the Gaggia will brew through very hard-tamped fresh ground very finely beans in the double basket in 25 second no problem, with great taste results.
Posted Tue Aug 3, 2004, 8:54pm Subject: Re: How to overhaul your Gaggia
Mike, I think it has to be the rubber plug - mine is cone shaped, not semi-circular on top. You could test it by putting the assembly into a glass of hot water and seeing if it expands. Anyway, there is no danger of the loose bolt coming out since it will hit the aluminium dispersion plate before the threads run out.
Gary, I did a google search on "nitrile" and "food" and it seems all sorts of nitrile hoses, gloves etc are FDA approved so you should be fine - it only releases toxic chemicals if burnt but that should never happen in a coffee machine else lots of other components are likely to become toxic too.
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