Refurbishing an old Rancilio Silvia

I bought an old Rancilio Silvia at ebay. This espresso machine seems to be somehow very popular – at least you can find a lot of information about it in the Internet including people upgrading it with a PID, pre-infusion, applying insulation to the heater and doing various other modifications. So it’s a good choice if you want to dismantle, repair und put it together again. Mine came in a really horrible state. The metal base was completed rusted, all plumbing was untight and if that would not have  already been enough the DHL guy smashed it to the ground so the base was bent and one of the rusted weld points was broken.

The vertical metal supports are bent by roughly 3 degree….
rost is everywhere
rust ate up a good millimetre of steel


Dismantle Miss Silvia

Taking it apart was not a difficult job. This coffee maker is very well engineered. You can sense that Rancilio produces professional coffee makers for gastronomy and the home style machines benefit from that. This is not only about the brass heater but the general construction like the thick metal sheet and the massive base.  All parts including the outer metal sheets are mounted to the base construction and can be easily removed after turning out the specific screws. Only the back metal case gave me some headache as the  screw was dull so I had to kill the screw head with an impact driver and a 4mm drill bit.

Derustifying the base

First I removed the the loose rust chips with a screwdriver followed by a treatment with my sanding disc which can be mounted to any impact driver. The result was not very satisfying, especially as I couldn’t reach all the corners very well. So I bought some hammerit fluid to get rid of the rust with the power of chemistry. I was probably not patient enough but  even after the 2nd treatment I still had way to much rust attached to the base.

Hammerit applied to all rusty areas


I remembered an article about rust removal with the help of electrolyse which has some big advantages over my previous attempts:

  • Rust gets removed in all areas that are covered by the electrolyte
  • No metal gets removed or damaged
  • After setup all work is done by the electro-chemical process, not yourself, except for the final clean up

I used a cheap ikea box I had at hand filled it up with water so that it would cover the complete bottom of the Silvia’s base frame. I added two packs of baking powder to create the electrolyte.

Two thin metal sheets acted as the anode (where you connect the plus cable of your power supply). The base frame was placed in the electrolyte bath and the minus cable connected to one of the screws on the base.

I didn’t exactly knew how much power I should apply and the instructions I had were not really precise on this. I started with 24Volts which resulted in a 3 ampere current which seemed fine to me. The chemical reaction started right away visible in little bubbles that came up from where most of the rust reside.

I kept the process going for almost 48 hours and after that, all rust had gone and the metal was covered with a thin layer of black ….., which I removed with a brass brush.

Cutting the metal sheet into two pieces for the anode(s).
….I actually didn’t cut it but bent it into both direction multiple times.
….the electrolyte gets blackish after a couple of minutes already.
The complete setup including power supply.
I used a multipurpose charger, a cheap 12 volts car battery charger would work fine as well.
This is how it looked like after 48hours operation.
And this is how the anodes looked after the process completed.

Priming & Varnishing the steel base

I bought primer and black varnish aerosol cans at amazon and applied that first coat of primer right after I had removed all the coverings from the electrolyte bath to prevent it from rusting again. Since black on black isn’t a nice contrast I took a screw driver and swept through all corners with gentle pressure to find areas where the primer didn’t join with metal or old varnish but with loose leftovers from the electrolyse process. I sanded those areas again and applied another coat of primer.

Initially I wanted to fill all the areas that were treated badly by the rust but since they were all not visible after assembly and it wouldn’t give any structural improvements I decided against it. I smeared epoxy into some of the gaps that might be  reached by water during operations though. Also I epoxied the transitions between the frames where one of the weld points broke.

Base Frame after the first coat of primer
The primer didn’t stuck at some areas where I didn’t remove the electrolyte mud properly.
Epoxy covered by primer.


Decalcifying all water-bearing parts

In parallel to the work on the base frame my wife and I decalcified all water-bearing parts. Dismantling the boiler, the steam valve and pipe was quite difficult as all screws and coupling nuts didn’t want to turn at all. I applied some WD 40 which helped a lot and after a lot of carefull back and forth movements with the appropriate wrenches I could finally loosen them all. Well, the nut that connects steam pipe & valve still didn’t want to move after a 24 hour bath in WD40 so I had to use a pipe wrench. Unfortunately I left a lot of marks on the nut and the connection with the pipe was so tight that I turned a spiral into the pipe. We decalcified the boiler with citric acid and all other parts with vinegar essence

A lot of calc appeared after the boiler was dismantled. I Can’t imagine that the coffee from this machine was still tasty.
It seems that this happens even if you decalcify your machine on a regular basis.
so I will probably need to open and clean the boiler every couple of years for full maintenance.


The spiral copper pipe might break in the future and needs to be replaced.
Nice too see that even the hardest calc affection is 100% reversible. All surfaces are really smooth after 24hour citric acid treament
We placed all parts in a tub to avoid acid spreading everywhere
We put pipe cleaning brushes inside the copper steam pip to keep the acid on the calcified area and to remove the calc mud afterwards.
Same trick with the pipe brushes on the steam valve.
Some kitchen utilities helped to level the lower parts of the brew unit.
Some fabric to keep the acid fluid on the areas that required treatment.

Soldering broken parts of the steam pipe

After all the descale work was done I started to mount the boiler on the base frame again. Next I wanted to mount the steam pipe but then I realised that one of the fittings broke when I initially dismantled the machine.  I spent half a day to find a replacement but could only get one for a more recent version (V1 or V2) of Miss Silvia. So I ordered the necessary equipment to solder the brass fitting. After a 3 day compulsory break I got a burner powered with camping gas, silver solder, flux and a ceramic stone. I applied some of the flux to both parts of the broken fitting, placed them on the ceramic stone and heated them up until they started to become red. Then it was just a matter of touching the crack with the silver solder and two or three centimeters melted instantly and nicely infiltrated the crack and covered the surrounding areas. Much easier than I though!

Steam pipe after soldering with silver solder.
The silver solder nice covers the entire crack and settled even in the inside of the pipe.



The reassembly process was as straight forward as dismantling the maschine. I applied some teflon seal tape to all the threads of the water-bearing parts because none of them seemed to be water tight when I got the machine (water arrears on all connections). I just had an issue with placing the electric connectors to the right positions on the switches. I initially had numbered them all carefully but forgot to note the free pins on the switches. Fortunately there a free circuit plans available in the internet. I did a dry run without any of the metal covering sheets mounted to see if everything would be water-tight. And it was besides the steam-valve which I will accept for now and fix with the next maintenance.

Before installing the outer case I insulated the boiler to reduce warmup-time and genreal energy consumption. There are pre-cut sets available at ebay but I decided to go for the cheap way and just ordered 1000 x 100 x 10 mm of Armaflex HT which can be easily trimmed with a utility knife.

Armaflex HT insulation of the boiler.
All “warm” parts are covered with insulation.
Before dismantling I numbered all the electric connectors.

Argh. Although being super careful some smaller scratches did appear on the newly painted base frame.
Miss Silvia at its final position in our kitchen.

Final thoughts about my Rancilio Silvia refurbishing project

This project was a lot of fun, especially as I learned some new techniques like hard soldering with silver solder or the  electrolyse derust method. Also, this type of espresso machines will always require some regular maintenance that goes beyond the usual decalc flushing with citric acid. Knowing the machine in detail will make such maintenance a lot easier and less expensive in the future.

So and how does the coffee taste? Well, we just had a couple of not so great espressi and still need to learn all about temperature surfing, beans, grinding and so.

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