# gaggia classic 2001 - water unclear, taste sweet/metallic



## dncarreira (Jul 8, 2018)

Hi there.

I've bought a 2nd hand gaggia classic, the sticker on the bottom says 11/2001.

I have noticed that water coming out the brew head has a sweet taste. I know this is subjective, but that's what it tastes to me. After searching online I now think this may be a metallic taste after all - not sure though...

So I pumped some water into a glass container and I can see some kind of suspension on the water that clears after a while but not completely.

I then proceeded to backflush with pully (with correct product). Washed with plenty water just letting the machine pump clean water through the brew head. No change.

Then I descaled with gaggia descaler. A few flakes got out. I though that was not too bad. Then I started flushing water waiting for the flakes to stop but they never did. Always some 2 or 4 small flakes still come through after 10l flushed...

I made a video of one of the initial flushing. You can see the quantity of the flakes on the bottom of the glass flask. You can see clearly the suspension I'm talking about. The foam at the top does not appear anymore (I guess that was still the descaler showing up?).

I then took some photos of the machine insides. It looks quite good to me, but then I zoomed to the bottom corners of the boiler and got a bit worried. I can see some residue that I don't know what it is.

So I'm asking your advice. What should I do? Replacing the boiler seems a bit out of my league... so if that's the case I'll be considering selling to someone more apt than me. Hoping something easier that I can do to remedy this...

Thanks for your time.

Duarte

Video:

https://photos.google.com/share/AF1QipMC2Onlc9EtPoj8zne6LKCUUvZtBct3CGXg1dcLPFYQl9 rC2clPbz9zjLzy8yF4ew/photo/AF1QipNyKyUIaUflEZCqBTHFwkuopfVwtu5Gqke3TMaF?key=U E01MEM3Q1g4bHZQclBUZEt6b29YVkNXSHBRdUpB

General top view:










boiler bottom corner 1:










detail:










boiler bottom corner 2:










detail:


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## dncarreira (Jul 8, 2018)

well I have just found another thread in another forum that describes my situation exactly:

https://www.home-barista.com/espresso-machines/neverending-citric-acid-residue-after-descale-t11840.html

The difference being mine is an old machine, not new.

The main suspect seems to be galvanic corrosion. But no solution though.

Searching for galvanic corrosion on gaggias I don't find any solution. I can disassemble the machine and give the boiler an acid bath and hand sand it and the base. But this seems counter-intuitive to me as I would corrode the aluminium and facilitate water contamination with metal. Or is this bad reasoning?

The flakes that come out from the machine do go down on water and do not float "up"... but are white. So I'm thinking it's scale, not metal.


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## ashcroc (Oct 28, 2016)

dncarreira said:


> well I have just found another thread in another forum that describes my situation exactly:
> 
> https://www.home-barista.com/espresso-machines/neverending-citric-acid-residue-after-descale-t11840.html
> 
> ...


It certainly sounds like the boiler is scaled up. If it's been filled with tap water in a hard water area it's a safe bet it will be. Are you sure it's a metallic taste & not chalky? The Espresso Shop sells a service kit with all the seals you need & new thermostats too as they can degrade over time.


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## El carajillo (Mar 16, 2013)

If it has been left standing with water in for a long time it probably is loose scale and should be ideally cleaned out by dismantling, continual flushing may well move the scale and block the solenoid valve necessitating a strip down.


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## dncarreira (Jul 8, 2018)

I've only had it for 3 months and have used ph 7.6 bottled water for the first2 months and then ph 6,5 after since my coffee roaster told me alkaline water could be the cause for some bad taste I'd been getting. A bit less alkaline water seemed to solve that.

Before that I don't know how it was used...

The problem with dismantling is that I'm really terrible at that! And in Portugal there isn't really a community of home espresso owners to help out or even provide that service.

I'm thinking 1st thing to do is analyze the water coming out because now I'm worried with al contamination... if it checks out ok then I'll start studying the dismantling process with more detail.

thanks for the input.


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## dncarreira (Jul 8, 2018)

Forgot - as for taste, honestly it tastes sweet to me... haven't gotten a 2nd opinion though... it just seems just slightly sweet hot water...


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## ashcroc (Oct 28, 2016)

dncarreira said:


> I've only had it for 3 months and have used ph 7.6 bottled water for the first2 months and then ph 6,5 after since my coffee roaster told me alkaline water could be the cause for some bad taste I'd been getting. A bit less alkaline water seemed to solve that.
> 
> Before that I don't know how it was used...
> 
> ...


Plenty of guides on YouTube to help you as well as several threads here. They really are quite simple to work on. Just label the wiring to make sure it goes back correctly & take loads of pics for reference when putting it back together. Until you've stripped the boiler you won't know what condition it's in. Worst case you're looking at a new boiler needed but it could very easily just need a descale.


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## L&R (Mar 8, 2018)

Probably your machine is full with scale and residue. It will need full dismantling and cleaning. Descaler can't help when the boiler is clogged.

Use WD-40 or similar before trying to undo rusted boiler bolts. Good luck!


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## dncarreira (Jul 8, 2018)

ok guys thanks for the encouragement.


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## dncarreira (Jul 8, 2018)

So I have sent water from the machine to a lab for analysis. I asked for metals and calcium, namely aluminium and copper+zinc (brass) since these are the main components of the boiler and boiler base where galvanic corrosion occurs. For the ride I asked for iron and nickel. Some surprises here...

These are the results:

Parameter ............ units ............... result ........ regulated limit for human use

*Al* .............. ug/L (same as ppm) .. *3,8e+3* .... 200

*Ni* .............. ug/L ......................... *1,8e+2* .... 20

Iron ........... ug/L ......................... 34 ........... 200

Ca ............. mg/L (1000x ppm) ..... 32 ........... none

Copper ...... mg/L ......................... 0.056 ....... 2.0

Zinc ........... ug/L (ppm) ................

So there is leeching of aluminium and nickel. I expected Al and Zinc from the boiler. Nickel I don't know where it's coming from...

I've read about nickel effects and it seems to be quite harmless. As for Al haven't read anything yet, but from what I heard opinions range from harmless to giving you a fast ticket to dementia.

I think this is a big warning sign to buying or using oldish coffee machines. And got me thinking about other stuff we use in the kitchen too...

I now have to decide wether to dismantle and clean/replace the boiler, or sell it to someone more handy at this kind of thing. Any takers by the way?


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## dev (Jul 28, 2017)

If the machine has the original Aluminium shower screen, you should never use something like Pully Caff. Also the descaler used for the boiler should be a mild solution of citric and lactic acid.

It's really not that hard to take the machine apart and clean the parts individually, once in a while.


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## L&R (Mar 8, 2018)

These machines are dangerous, give them all to me


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## dncarreira (Jul 8, 2018)

L&R said:


> These machines are dangerous, give them all to me


I wouldn't go so far, but definitely consider selling reasonably priced...


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## dncarreira (Jul 8, 2018)

I'm reviving the thread because I have disassembled and cleaned it! Very happy with myself at the moment...

Some pics of things before cleaning:

















And after acid bath and scrubing:


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## Morningfuel (May 19, 2016)

That looks like an improvement...!


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## El carajillo (Mar 16, 2013)

Definite improvement  I would suggest you obtain some wet&dry paper and something flat to work on eg ( small piece of glass)

Fold and rip the paper into 4 pieces 4" X 4", place it on the glass and wet with water + wash up liquid, gently rotate / rub the base of the boiler on the paper, rinse and repeat until you have a smooth - non pitted surface for the seal to sit on. :good:


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## lubos257 (Apr 7, 2021)

Hi, I'm just solving exactly the same issue. I'd like to ask, if the taste of water was improved after descaling (have you tested the chemicals again?)

My story is , that my boiler looked very similar - I descaled it yesterday. The counterpart of boiler , is massive brass part which is nickel plated.. the plating on my part is damaged, so it can be the source of nickel in the water.

There is copper tube inserted in that massive part - and the green oxidation on it !

I found two issues in my case. 1. I have an old machine and use it occasionally, and 2. sealings in the machine are old.. If the water stands in the boiler longer time, the water leak through the bottom sealing, and the air goes in to the boiler. I think, the copper oxidize in green color when exposed to wet air, like to roofs of old churches - this is definitive not healthy type of corrosion, but I hope it can be solved by changing of sealings (which I'm doing right now)

Different electrochemical potentials of materials like boiler (I don't know the exact Alloy , AlMg? ,or AlSi?) and Copper tube, or damaged unnickeled part of brass part can cause dissolving of boiler. This is probably the reason of pitting corrosion in the pictures.

I thought about changing the Copper tube for stainless steel - this would be great for eliminating of green oxidization. On the other hand, the electrochemical potentials between stainless steel and Al Alloys is even higher, in comparison with copper. So the pitting corrosion of boiler would be faster.

I think the ph of water should be in some range like 4.5 - 7ph, because more acidic or alkalines breaks down surface of Al2O3 which should be naturally created on the surface of boiler and this should protect it from corrosion issues. If the water would be in good range, the Al2O3 should protect also from electrochemical corrosion.

I suppose, that descaling proccess causes short time corrosion..but for 10years it can be days of wrong conditions..

Lubos


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