Circa 1980's La Marzocco GS2

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IamOiman
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#1: Post by IamOiman »

I am quite unexpectedly starting a new project today that is not a lever or hydraulic machine, but rather my first pump machine. It is a 2 group La Marzocco GS2 that I purchased local from a coffee technician in Brooklyn. It was mediated by another tech who is a friend of mine from Vera Coffee Solutions in Connecticut, and his shop is where I picked up the machine this past Wednesday with my dad in a 250 mile round trip excursion to Bridgeport and back.


I knew about his machine in June, when I made an offer that at the time was rejected. However, the coffee tech is now downsizing his inventory, and I made another offer this month that was accepted by him. It was a good price I think, less than 1k. However, the machine is in pretty bad condition. The following pics are when I was picking up the machine after inspecting it for any freeze damage (there so far appears to be none).





I brought home the machine, and I have made some notes on what I think is changed and potential issues it has.

A portafilter is missing, a steamwand and its original knob were changed out, the water fill lever is broken, the steam boiler pstat and autofill have been replaced, I think there are two tiny leaks on the brass fittings of the brew boiler, one of the plastic panels was smashed and had an unsuccessful glue repair, and most surfaces are pretty scratched up and or dirty. The biggest mystery about this machine is whether it was an auto design, or if it was a manual paddle. I see the MP caps on the groups, but the frame seems to indicate the opposite. Some investigation is needed.

Even with the issues listed above, there is a prior unknown-to-me reverence for the GS series machines produced by La Marzocco, back when they were still a relatively small player in the espresso machine market compared to the giants like Faema, Cimbali, and Gaggia. GS machines were imported into the US, but according to Marzocco employees who were around in that time it was maybe 100 machines being produced a year during the 1970's (any confirmation or refuting is encouraged here on that statement). This machine is from that era, and I am hoping that I can learn to appreciate the craftsmanship and different operating philosophy compared to lever machines. I hope to show as much as possible in this project just like I did for the Cimbali Gran Luce, as there are not a huge catalogue of restoration threads out there.








-Ryan
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IamOiman (original poster)
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#2: Post by IamOiman (original poster) »

Initial disassembly

I moved the machine downstairs last night and began tearing into it today. It is not a super heavy machine compared to some of my other levers I have. I estimate it weighs 70-80lb.


The first thing I wanted to do was remove the backsplash. It comes in three panels, and the replacement valve needed to come off first before one of the panels would move. There was a cotter pin I need to take out to do that after unthreading the white part of the cap. Doing this allowed me to see the brew boiler and front more easily. There are two solenoid valves under each group that at first glance appears to have a pipe just looping around and going back into the group, but it actually has a purpose doing this.






The group caps have two bolts securing them to each group. Taking them off revealed the brass caps that seal the top of each group. There are three additional bolts to take off that secure the portafilter locking pieces and the cap against the bottom and top of the group, respectively. There is a smaller bolt that threads into the top of the group too. The former has a 6mm allen head and the latter has a 5mm head. I was able to remove the bottom housing, but the brass caps are quite stuck at the moment. I am still working on getting them off. I took off the solenoids and pipes after that.







-Ryan
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#3: Post by IamOiman (original poster) »

Disassembly and taking off boiler fittings and groups

I got interrupted in writing my posts, but continuing onwards I began to prep taking off the groups. If I understand the groups correctly, the eight bolts that thread into brass nuts under the boiler surface are metal-metal sealing. I am not sure if this is necessary, but I marked each bolt's original location with a black sharpie for the left group. They are 11mm hex heads, and the bolt on the middle right (with 4 dots on the head) is fouled by a thread from an internal pipe that I can just barely fit a wrench. I used a socket for all the other ones. Once all the bolts are off, I got the group off with a strong tug, revealing the inside of the boiler for probably the first time since it was assembled at the factory.





There was still water inside the boiler, filled about 2/3 up. The old gasket looks pretty gnarly, and there is long term buildup of hard water deposits inside the group and boiler. To drain the boiler, I used a syphon to get most of it out. I also drained water in the steam boiler for a little under 3 liters total taken out. It is not something I recommend drinking.







To take out the clip holding the brass nuts, the four little prongs were bent inwards gently with pliers. The clip is not very thick and does not need a lot of force to bend. It requires some finicking and adjustment to get the clip out, but I got it done.




Before removing the right group, I had to take off the heat sensor. Since the brew boiler is filled with water, there is little or no steam to produce pressure, so instead it's managed by temperature sensing. This guy just slips out after taking off the wiring and right group solenoid pipes. Once taken out, I marked the group bolts with a pink sharpie and repeated the process.








Other fittings and valves were taken off too. The steam and hot water valves secure directly to the frame, but the left valve has a square hole, and the right valve has a round hole to fit into so the latter has a clip to secure it better. The heating element on the brew boiler will not be removed until I descale the insides.




-Ryan
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#4: Post by IamOiman (original poster) »

Boiler removal and more disassembly

With the groups and majority of pipes off I could prep for boiler dismounting. There is a stainless bracket in the rear that attaches to the boiler supports and body panel frame pieces that comes off as one part. Various fasteners, some not original, needed to come out.



Among the last pipes remaining are two water inlet pipes going to each boiler. There is a solenoid valve that normally spans between the two pipes (the brew boiler by default always has water going in with a mains connected) for the steam boiler autofill, but for some reason it was missing on this machine. I had to first remove the steam boiler pipe, then the brew boiler pipe. Otherwise the pipes would foul each other trying to come off without taking off the check/one way valve on each inlet.




There are various M6 bolts that secure the boilers to two boiler support frame pieces. The brew boiler has four bolts total, two on each side on the top and bottom. For some odd reason I see four holes arranged in the same pattern on the boiler supports for the steam boiler, but I only saw one bolt on the top element side that actually secured the steam boiler to the supports. Maybe someone forgot to add three brackets! I removed the boiler support on the autofill side so I could slide out the brew boiler first.






The steam boiler has a lid with five bolts that are the same style as the group bolts, where the bolt heads have a metal-metal sealing contact with the lid, but they are bigger in thread and head size (12mm and I think fine M8 thread). I marked the bolts and noted the wiring before taking off the steam boiler too. The boiler nuts were a little tight, so I removed them after taking the boiler off the chassis. The boiler support will not come off until the lid comes off, and as of tonight I have not been able to remove the lid from the boiler. It is very stuck on there due to deposits and old gasket.







The sight glass was one of the last things that I took off the steam boiler. The top pipe came off just fine, but the lower pipe had a really wacky incident where it appears that the solder or braze going into the boiler failed. I did the slightest tug with my 24 mm wrench and the fitting that is normally rigid and secured into the boiler started moving. Really crazy thing to see and an unexpected issue, but I think I can fix myself or otherwise get assistance.





I got pretty far in the disassembly process I think. There are some more things I did after the following pics but I'll write those up later. I will need to make a decision down the road about how I will want to configure the groups to manual or something like it was currently setup when I bought (as a schizo EE). I'm about 4 hours of work in at this point






-Ryan
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smite
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#5: Post by smite »

Great thread thanks for sharing. That machine really seems like it needs a ton of work. I look forward to seeing more of your progress. Any thoughts on how you will treat the outside of the machine? Will you try to restore the original look or something more customized?

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#6: Post by IamOiman (original poster) »

This is a machine that I am considering doing an full restore, like new chrome and everything. Very expensive if I go that path but it would look stunning. I think I will try to bring it back to factory spec from the exterior side. The FB sticker on the frame may be lost or taken off, but Daymond, a tech with Kent, is potentially working on some stuff getting refabricated like that sticker.
-Ryan
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#7: Post by IamOiman (original poster) »

Taking off the group brass caps

Each group has a brass cap on top that were both quite stuck on my GS2, presumably due to the gasket and old buildup. To get them off, I locked each group in the vise and used a utility knife blade to wedge between the cap and group. Doing this from multiple angles of attack and lighly rapping the blade with a hammer (using a handle for stability), I was able to separate the caps from the groups enough that I could pop them out with a bigger wedge. I know the bottom brass piece where the shower screen threads into can come off, but it is quite stuck at the moment too so I will try again later after soaking them.






I am told this is not the worst buildup out there, but it there is not a little amount. I may try to descale the insides only if I see the chrome is in good shape after cleaning it up. I know the pipe inside will come off after unscrewing the big hex nut.



-Ryan
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#8: Post by IamOiman (original poster) »

Disassembly of the sight glass

The sight glass has two pipes running from the top and bottom of the steam boiler. The bottom pipe was really clogged with deposits that I could rinse out. There appears to be a little drain or purge thread on the bottom of the glass body itself that has an allen head screw connecting to a thread. I did manage to get everything apart except for the broken boiler thread fitting that is still attached to the sight glass pipe.

To take off the glass I used a pin spanner wrench with 4mm pins to do the job. It was actually not very stuck, and loosened pretty easily. The glass is intact as is its o-ring gasket. The allen screw and its little fitting also came off relatively easily after heating it. I am pretty certain this entire sight glass assembly is still available today if I do need anything replaced.







-Ryan
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#9: Post by IamOiman (original poster) »

Valve disassembly

I picked apart all the valves except for the replacement steam valve. The steam and hot water valves have their own tap rods with similar gaskets. The steam valve has a piece on the end that is free spinning while the hot water tap rod has a rigid style and a smaller blind gasket. The o-rings appear the same between the rods, and may be the same ones used on Cimbali taps.




There are two 1 way/check valves for each boiler. The plated one goes to the brew boiler and the brass one goes to the steam boiler. The o-ring on the one way bushing inside appears to be a common style found on other machines.



The water inlet can be tricky if you are not careful. There is a very thin hex nut that compresses a gasket around the manual inlet tap rod. There is already evidence someone attempted to take it off and partially rounded the nut. I used a lot of heat and then a pair of knipex pliers to securely loosen the nut. The body that the tap rod and gasket are inside also unscrews. I dug out my pipe wrench to loosen it after more heat. I rarely use the pipe wrench, but sometimes there is simply not a good position to grasp a piece with both a vise and a wrench. Luckily I did not need to dig in the wrench super hard and there are minimum teeth marks on the piece. I did not take apart the tap rod itself (which has another gasket) because it is stuck with deposits.






The manual water lever is separate from the inlet valve. It was broken at some point in the past, and I will need to make a replica or source and original (probably the former).

-Ryan
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#10: Post by IamOiman (original poster) »

Stripping the frame bare

The frame has to big parts to it, a lower frame and an upper portion that holds the boiler and panels. They are secured by five M6 bolts that once removed simply allows the upper frame to come off. This reveals a lot of crud that I had to clean off, and allows me to remove parts like the feet and drain tray.




The feet all thread into the lower frame. There are little screws inside the feet that normally secure a cushion, but two feet had damaged screws and the other two had salvegeable screws. I used an oil strap wrench to get them off.





The last thing to take off was the data tag. It pops out via two rivets punched from the inside. At this point I consider this to be the end of disassembly. The lower frame has holes cut in where the make-shift buttons were installed. Perhaps that is a hint of what this machine originally was configured as? There is a similar machine on Kaffee-Netz that appears to have the buttons on the lower frame. I think it's the volumetric version with flowmeters, and seeing the flowmeters inside the group caps would indicate to me that perhaps my caps are original too. What happened was the machine was converted from an AV to EE equivalent with the flowmeters removed. I can't guarantee that is what happened but I think it's a good guess.
https://www.kaffee-netz.de/threads/noch ... gs-2.75023


-Ryan
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