So, for the update on Elektra Microcasa a Leva weak steam problem, I filled the machine with distilled water tonight and turned it on. It got to pressure as usual and when I got close by there was a new noise coming from it. It seemed to be coming from the steam wand. So I tried to blow some steam and it worked perfectly but the noise was still there.

I listened more carefully, turned the machine around to discover that a tiny bit of water was now coming out from A HOLE IN THE BOILER!!! Need I say I am not in a good mood. There was a small rust patch there when I bought the machine. I didn't notice it before getting home as it was against a wall when I first saw it. I didn't worry too much about the rust and thought I'd enjoy some good shots and worry about the rust in the coming weeks. It seems that the protective oxides that were removed by the descaling process might have been preventing water from leaking out that hole.

The hole seems pretty small as the machine still gets up to pressure and only a tiny drop gets out from it and then evaporates from the heat of the boiler. I now have to figure out how to repair (or most probably have someone else repair it) the boiler. There is also rust at the base of the piece that connects the sight glass to the boiler.

Any ideas?

I don't think it's rust because the boiler isn't steel. You could be describing pinholes. Sometimes those can be sealed with Loctite 290.

Well, it awfully looks like rust but you're right that it doesn't quite make sense. The connection between the boiler and sight glass is partially eaten through as if rust was eating it. I don't get it. I'll take pictures tomorrow.

What are pinholes? How do they happen?

Pinholes are tiny holes. One way they can occur is with aggressive descaling. Brass can also break down in ways that Robert Pavlis has described elsewhere. Since he's involved in this thread he might explain. It's possible that what you are describing is accumulated scale from bad water. Hard to tell.

Another way pinholes can be sealed is with brazing. I have an Olympia Express Cremina where I sealed pinholes with Loctite and haven't had problems. It's a common and inexpensive way to deal with the problem. It is also possible that fittings are not securely sealed, and that can sometimes be helped with threadlocker. Or, sightglass gaskets may need tightening or replacement. I think photos would help a lot, good quality close-ups if you can provide those.

Thanks! I'll post pictures tomorrow. I just hope it can be easily fixed. If not, I might contact Pootoogoo as he seems to be quite an expert in restoration and local to me.

So, here are the pictures:

This is where the water coming out from. The height of the "stain" is around 20mm:



This is another corrosion stain that's about 5mm high.:


A third one, around 5mm as well and near the sight glass connection to the boiler. (picture on its side):


The connection between the sight glass and the boiler (picture on its side):


And a green stain I don't like underneath the piece that's in between the steam wand and the boiler.


I'm starting to get a little bit pi**ed at myself for not inspecting it better before buying.

Any pointer on how to fix all of this?
Thanks!

Patrice,

Thank you for the excellent photos. Those leak points look troubling. Perhaps rpavlis will comment, since he knows about this and has a machine like yours. Here is a thread he wrote about such corrosion issues.

Corrosion prevention in espresso machines

Are you able to see anything on the inside of the boiler? (I have an inexpensive boroscope for such inspection but that is not part of everyone's toolkit.) I also like your idea of having Sebastien (pootoogoo) look it over if he is available.

I have a bore light to look inside the boiler but don't see much except that the descaling process took away some protective oxides. I tried to take pictures without much success as the opening of the boiler is so small. I'll try to look again tomorrow and post here if I find anything that could help.

The seller was using Brita filtered water (he had the machine for around a year, I think) and I don't know what kind of water the initial owner used for the first twenty years. I was told the machine was professionnally serviced about a year and a half ago but I don't know if they also checked the boiler at the same time.

Thanks for all your help! Let's just hope I can fix this and that I don't have to pull it apart to sell the remaining pieces...

I suspect the problem was that a former owner used water with high chloride concentration. Perhaps other pollutants could have contributed too.

I hate to sound professorial again, but I think I should explain the chloride problem. Copper metal cannot react with water or aqueous acid in an oxygen free atmosphere. However we do not live in an oxygen free atmosphere! Copper can, and does, react with oxygen. in water that is slightly alkaline, neutral, or even very slightly acidic copper oxide is insoluble and coats the copper (or copper alloy) and protects the metal very well for a VERY long time. Descaling with acid tends to remove some of the oxide coating, or all of it when the acid strength is high. The oxide coating will soon reform, but if one keep descaling again and again, one is gradually removing metal.

Now--enter the real villain, chloride. Cuprous chloride is insoluble in water. Solid CuCl is actually a larger molecule, typically a tetramer. (four of them associated together.) Oxygen can oxidise the cuprous ion to cupric. The cupric ion remains in the structure and reacts with elemental copper forming more cuprous ion. The insoluble copper chloride material just stays there and as the reaction proceeds it "eats" the copper.

The reaction can be written in a somewhat simplified way thus:

Cu⁺ → Cu²⁺ + e⁻
Cu²⁺ + Cu → 2Cu⁺

The O₂ from the atmosphere accepts the electron ( e⁻ ) and the reaction keeps going over and over. Every "turn" of the reaction system ends up converting one metallic copper atom into another cuprous. When given a chance this just keeps making more and more cuprous ion in the form of cuprous chloride and eventually there is a deep pit or hole in the object.

The reaction happens much faster at higher temperatures.

Before people understood chemistry this process was given the name "bronze disease". Remember that brass is really zinc bronze. However, pure copper can also do this. Our University had to replace a lot of copper pipes because this reaction resulted in their developing holes and our having indoor "rain".

This is less likely to occur in slightly alkaline water because the oxide coat can protect better.

Polishing away the pitted area and treatment with strong carbonate solutions, allowing the part to soak for a few hours can be used as treatment.

Robert, thank you for sounding like a professor so that you could fully explain the chemical process. What would you do to patch those holes once the reaction has been stopped?