# Commercial 2 Group Repair/Restoration (pic Heavy



## stub24 (Sep 22, 2013)

Hi all, just though I would share my foray into repairing a non working 2 group Grimac Zola. I bought this item as a spares or repair as it was not tested by the owner so I picked it up quite cheap. On inspection it looked in pretty good nick, all bodywork was there with 2 portafilters included.









Opening her up and I could see why it wasn't tested, most of the cables were unplugged with some cut in half, looks like it needed the wiring sorting and a good clean.









After much head scratching and drawing out the wiring on a piece of paper, I had it all wired correctly, turns out a wire to one of the three way solenoids was actually connected to the water level probe earth??? After removing 2 poles of the heating element so I could run it on 13 amps, element was supposed to be 3200 watt, I tested all of the functions and to my surprise it all worked. It had leaky connections but I was fine with that as I would be stripping it down.









More to come....


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## stub24 (Sep 22, 2013)

First step was to do the steam and water valves

Before









After









I thought they turned out quite nicely.


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## stub24 (Sep 22, 2013)

Now to remove the boiler and associated pipe work, the HX pipes took some work to remove from the groups but I got there eventually, heat and patience. Here are some pics of the hx pipes full of water but you can see some of the scale build up.









It was a similar story inside the boiler, lots of lovely scale.









I decided to descale the boiler and pipe work before proceeding further with the strip down, after many hot citric acid soaks and a polish here is the results.


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## stub24 (Sep 22, 2013)

Now it was the groups turn for some attention, the shower screens and seals were surprisingly easy to remove but the dispersion screws/discs were another story.

Before









I haven't got a detailed pic of the after but here they are with the rest of the pipework and boiler


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## stub24 (Sep 22, 2013)

Now that most of the frame was exposed it was easy to take out the electrics as a set which just left the frame, my initial thought was to powder coat it but as it wasn't in too bad a condition I just gave it a clean.

The result









Stay tuned for reassembly....

Thanks for looking so far

Stuart


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## coffeechap (Apr 5, 2012)

Nice thread keep if coming


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## ronsil (Mar 8, 2012)

Great job, very interesting, looks well worth the effort.


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## Fevmeister (Oct 21, 2013)

I wish I knew how to do that! Very impressive, well done and keep us posted with as many pics as possible!


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## GS11 (Feb 20, 2013)

nice work. look forward too more pics:good:


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## glevum (Apr 4, 2013)

I love these restoration threads...well done


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## Taylor The Latte Boy (Dec 9, 2013)

Awesome thread! How did you come across the coffee machine? I'd love to try something like this next year if I have some time, as a hobby.


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## stub24 (Sep 22, 2013)

Thanks for all the comments guys, when I had access to a garage I used to restore motorcycles so once I moved to a house without a garage repairing a coffee machine made sense. I made sure to ask permission from the other half to take over some of our living room!

Fevmeister: If you have the time its well worth doing as you get to understand how you machine actually works, I found the best way to learn these things is to just jump in!

Taylor the latte boy: There are always lots of these types of machine on that auction website, I was looking for a semi automatic version to keep the electrics simple. This one was only a 30 min drive away so i thought it was worth it.

So back to the restoration, by this time I had all the components layed out ready to go back in, I checked the element resistance to make sure it was okay before I continued. Turns out that the element was a 2400W La Marzocco one, this meant I could change the wiring to a standard 13 amp system yey! I bought some 1.5 mm 3 core wire to replace the really short power cable it came with. The re wiring was quite easy as the heating element is separate to the rest of the electronics bar the pressurestat obviously.

Wiring back in with old power cable









At this point I should say that I have not descaled the pump, the reason being that it turns freely and I didn't want to needlesly destroy the vanes.

Plumbing and pump back in









....


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## stub24 (Sep 22, 2013)

Next step attaching the groups









Before I ventured further it was time for a test









Everything seemed to work without leaking, a good sign, the pump however would not pressurise past 7.5 bar on a portafilter pressure gauge and the brew pressure gauge was no where near accurate. I will be replacing the gauge because I can't guarantee its accuracy if I just changed the position of the needle. The pump and its associated balanced by pass valve was removed, I used Paul Pratt's technique for descaling the pump.

1. Put the pump in hot citric acid solution

2. Turn the pump every five minutes

3. Remove after 30 mins

After putting it back in the machine the pump was variable from water inlet pressure to 12 bar, which is when the overpressure valve kicked in and drained into the drain cup. Success!


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## stub24 (Sep 22, 2013)

Here are some picks of the machine with its clothes on and making coffee!!









I plan to use it for a couple of months before going back to the Cherub to make sure it all works, unfortunately its a bit big for my kitchen so I think I will eventually have to sell it. Incidentally does anybody have some tips for getting a mirror polish on the, what I believe to be, stainless steel panels?

I think for my next project I would like a lever or a double boiler machine that is small enough to replace the cherub 1 or 2 groups I don't mind.

Thanks again for looking, i think I was oddly fortunate to have such a simple and straightforward rebuild.

Stuart


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## LizG (Oct 25, 2013)

Wow, looks like a brand new machine.


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## stub24 (Sep 22, 2013)

If you are interested there are more pictures here http://www.flickr.com/photos/[email protected]/


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## Milanski (Oct 10, 2013)

So cool, wish I was this handy!

Thanks for posting.


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## jeebsy (May 5, 2013)

Looks excellent now, great job


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## 4515 (Jan 30, 2013)

Great restoration project - and plenty of pics

Thanks for posting


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## ronsil (Mar 8, 2012)

That's a great job - Thanks for letting us see it


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## Charliej (Feb 25, 2012)

Nice work, I found it quite inspiring as I have the skills needed to restore a machine but not the space lol, but maybe one day.


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## Dylan (Dec 5, 2011)

Awesome thread, mirror polish can be achieved by going down in stages of polishing compound. I did some reading a while back when I had to polish a Classic and bits of info to take away were.

1. Use a powerful drill that wont slow down with pressure, around 3000RPM

2. Heat is your friend, help achieve a good shine.

3. Patience ^_^ (something I lack)

Cant remember where I got em but these are the compounds I used http://www.durston.co.uk/lan-multi/prod-c-luxor.php


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## stub24 (Sep 22, 2013)

Thanks for all your kind comments, hopefully I will be able to get my hands on more machines and share the results. I have one question about this machine, the brew pressure gauge is located between a non return valve and the pump so does not measure the hx pressure unless the brew button is engaged. Surely it would be wise to locate the gauge after the non return valve so you would be able to monitor the pressure in the hx pipe. This would then give you some idea if the pressure reaches a dangerous level as it heats up or if you have a leak in your thermosyphon loop?

thanks for the info d_evans I will check that out


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## dogday38 (Feb 15, 2012)

Really enjoyed your thread, thank you. I have neither the space or the skills but i bloody well wish i did.


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