Gaggia Tell 2 Group and Reserve Rebuild

DMH

Managed to remove all the group studs using the double nut method. Boiler and heat element threads and studs are all good. Do you think I need to do anything with the boiler? The guy selling the machine said it needed 32 Amps. I think these elements are 1750W each which at 240V should be about 15 amps. If I run a couple of 2 group elements then I would be looking at 2500W total which may be achievable with a standard 10 amp supply. Not fussed about heat up or recovery time since this whole exercise is nonsensical. Naturally I will have my electrician verify the logic and wiring before I proceed. [attachimg=1][attachimg=2]

DMH

Got the groups open. They don't look too bad but I need to give them all a good clean to see where I am. Unfortunately the large hex nut on one of the groups is seized. Can't recall if I read on a previous rebuild that only food grade materials can be used within the group. If this is correct I may to find a big spanner or alternatively clamp the hex nut and bolt the group flange to a long piece of wood to provide a bit more leverage. [attachimg=1][attachimg=2]

DMH

Can anyone recommend a good powder coater and electroplater in Melbourne. Not fussed about location? Thanks

Koffee_Kosmo

I'll be watching this rebuild / restore thread with keen interest :thumb: You did not waste any time with it :angel: I think you will find powdercoaters pretty easily in Melbourne KK

C-man

this should come up good!

DMH

Does anyone out there have any experience on how to zero a gaggia pressure gauge. The unit is precise but reads 0.7bar too high. Do I need to remove the hands and then reinstall in the correct zero position? [attachimg=1] [attachimg=2]

UNM

I thought 32 amp was unlikely. Two 1750 elements sounds quite believable. As the machine has space for two elements, you have a lot of options and it could be configured so a simple jumper install allows it to run 10, 15 or 20 amp. For now, I would be inclined to run it as is on 15amp, or with a single element on ten amp if you do not have a handy 15amp outlet. Since the boiler is out, you may as well nip up to your local car wash and give it a blast with the pressure washer. Unlikely it needs any more than that. To remove that bolt, you could try putting it in the freezer for a day then give it some heat. Repeat as necessary. Removing needle and repositioning seems like the easiest way of resetting the gauge

DMH

Thanks for your help. I think I'll just wire up a single element for a 10amp supply with the option to wire up the second element at some point down the track. The pressure gauge has now been rectified. I will give the boiler a bit of a blast and intend to reassemble it with new gaskets, SS studs and SS bolts.

kofekitt

Nice work so far , i had an identical 3 group Tell, i think it was also originally from Melbourne! I restored it, but ended up dismantling it for parts for an even older 3 group Gaggia. Most parts for the valves etc are still available, i even have a few spare valves if you end up needing anything. Groups are best converted to the 3 or 4 seal and 'v' ring set-up to replace the old asbestos seals. The currently available spacers sold from most suppliers are not usable in my opinion. Let me know if you'd like the contact details for some brass 'v' rings and seals.

Brett_H

What a brilliant thread! Thank you for sharing your wonderful project!!

DMH

kofekitt wrote:

Nice work so far , i had an identical 3 group Tell, i think it was also originally from Melbourne! I restored it, but ended up dismantling it for parts for an even older 3 group Gaggia. Most parts for the valves etc are still available, i even have a few spare valves if you end up needing anything. Groups are best converted to the 3 or 4 seal and 'v' ring set-up to replace the old asbestos seals. The currently available spacers sold from most suppliers are not usable in my opinion. Let me know if you'd like the contact details for some brass 'v' rings and seals.

Hi I'm pretty sure that I have seen pictures of your machine and it was one of the factors which helped me to decide to take this on. Any idea when these units were built. My machine does not have any indication on the boiler but I can faintly see Coffee Mio written in black texta. Coffee Mio are Melbourne based and are/were the Gaggia agents. I believe they actually built machines in Melbourne and have a similar machine in their museum. When I get a chance in the next week or two I will drop in and see them. In regards to seals I am intending to use the 4 seal and V ring set up option and therefore would greatly appreciate your source for these items.

DMH

Brett H wrote:

What a brilliant thread! Thank you for sharing your wonderful project!!

No need to thank me. Apart from playing with my L1 I am a total novice in this area and this forum is a knowledgeable and very friendly source of information.

DMH

Hi I'm having problems in that the pressure-mercury switch is not holding pressure. It appears that the pressure switch is manufactured in two main sections which are threaded and a diaphragm is sandwiched between the two. The diaphragm appears OK but I have leakage on the main thread. Before I use brute force to open this can anyone confirm that these can actually be opened and if some form of o ring is required. Thanks [attachimg=2][attachimg=1]

kofekitt

PM sent with contact info for parts, Can't help with that Pstat sorry as mine had the wobbler weight and was converted to Sirai. The contact details i sent you may be able to help with that pstat though. Good luck

Koffee_Kosmo

I know that Bezzera use a special high temperature - food grade - non hardening - thread lock sealer Hope this helps you in your build The one I would recommend is the Permabond A131 But do your due diligence and research it for suitability http://www.permabondllc.com/TDS/A131_TDS.pdf [attach=1] KK

DMH

Inside the pressure switch. The existing gasket is quite hard, brittle and now broken. I'm sure any high temp material will do the job but I am starting to lean towards a sirai pressurestat. Also I appear to be missing the wobbler weight and the machine was equipped with what looks to be a spring loaded pressure relief valve. [attachimg=1] [attachimg=2]

kofekitt

If the machine had a functioning pressurestat, there should be no need for a wobbler weight, but some still have them as a safety feature. The valve you have pictured is a standard safety valve, which has a spring and a teflon seal normally. You can just replace the spring and teflon seal, but most people just replace with a new valve - Note ; gaggia use a 19mm safety valve, not the more common 3/8"

borat123

I can vouch for the Sirai pstat. Not expensive and the dead zone on mine is less than 0.2bar. Bezzera also have a combo safety / anti-vac valve which in my case saved me having to plumb in another connection.

DMH

Frame and outer panels are at the sandblasters prior to powder coating. The stainless steel panels, trays and other components are with my favourite fabricator for refinishing. I have ordered the element gaskets and boiler basket and am having the boiler to group head and the mercury pressure switch gaskets fabricated. I also have new bolts for the boiler end plate. I couldn't get engineering studs for the groups and elements so I plan to cut these from a length of 316SS M8 threaded rod. The machine was originally supplied with brass nuts to hold the group head so I have purchased SS dome head nuts. Since SS to SS can be a real pain I also picked up nickel based antiseize. I will have a bit of a go with polishing the boiler and piping but pretty much now have the frame, external body and boiler area under control. I plan to have a play with the mercury switch once I have the new gaskets and will decide once I get a feel for the consistency of the switching pressure. I will replace the pressure relief valve but to my surprise my unit and I think many other older gaggias are not equipped with vacuum relief valves. I assume that these units are started up with a steam tap open. I have various spare ports so I will also install a new anti-vac valve. The groups are mostly apart but the pistons are seized with the connecting pins. I will give them a few days with WD40 before I apply heat. I have ordered new springs but wait until the groups are properly apart and cleaned before I do much further with them. I haven't touched the reserve group but I know it has a broken handle. At this stage if I can source a third lever group I would be happy to ditch the reserve group

Koffee_Kosmo

borat123 wrote:

I can vouch for the Sirai pstat. Not expensive and the dead zone on mine is less than 0.2bar. Bezzera also have a combo safety / anti-vac valve which in my case saved me having to plumb in another connection.

I remember talking to you at the time about the all in one Bezzera anti-vac valve Turned out to be a good mod :thumb: KK