# Seized bolts on Gaggia Classic Boiler



## Randleog (Jul 6, 2014)

As you can see from the image (how do I rotate!) I have the nightmare boiler problem. Heavily lime-scaled is the least of it. The two solenoid bolts and and one boiler bolt have corroded and then sheared, leaving heavily corroded stubs in the group.

Aware that an attempt to drill out the stubs would be doomed to failure, but not wishing to sacrifice the group, I ponded this for a while, then Googled it.

Apparently Ammonium Aluminium Sulphate, otherwise know as 'Alum' will eat away at the ferrous metal but leave the brass and chrome behind. I have ordered 500g of this stuff over the internet and plan to run this experiment (boiling Alum) using a leftover boiler element in my workshop when it arrives. Apparently the ferrous material (the bolts) will corrode rapidly into a rusty sludge.

I'll keep you posted!


----------



## 2cups (May 6, 2019)

Owch. I've had some luck using a dremmel to cut the head of the boiler bolts (plus citric acid and a lot of persuasion), but the stubs look like another level of problem.

Good luck with the experiment, rather you than me. You don't want to hear this, but might be time to invest in a new (or 2nd hand) boiler.


----------



## Abcan (Jan 10, 2020)

That's a right state! Are you able to file two flats on the stubs and then try turning with a spanner? Use some penetrating oil like Plus Gas or similar and soak for as long as possible. Keep us posted.


----------



## Blue_Cafe (Jun 22, 2020)

Have you tried hitting it with a hammer?

If that fails, try fire .....


----------



## MartinB (May 8, 2011)

Probably got a spare group head should you require one!


----------



## Nightrider_1uk (Apr 26, 2020)

Drill them and use Easy Outs to remove them. Soak them first for ages in penetrating oil first.


----------



## Randleog (Jul 6, 2014)

I decided to give the 'Alum' solution a shot. My workshop currently resembles the nutty professors laboratory!

The procedure involves boiling the affected item (or rather keeping it at just below boiling point for several hours) in a super-saturated solution of Ammonium Aluminium Sulphate for several hours. The ferrous (steel bolts) will dissolve into salts leaving the non-ferrous metals (chrome and brass) untouched. My wife took a dim view of using the gas hob in the kitchen for this.

As you can see, I employed an old boiler as a heating element. I made sure that a thermostat was in-circuit to avoid meltdowns. Nonetheless, this was clearly developed in a Health & Safety free environment and the opportunities for premature death are top many to mention, so I wouldn't recommend anyone else try it! Readers in the US please note, the wiring arrangement is for 240 Volts, 'in series', whereas you'd have to wire in parallel to ensure proper heating.


----------



## Randleog (Jul 6, 2014)

So, I completed the exercise, boiling the group in a solution of Alum, and the result is below.

A few caveats: it is a dangerous business. I boiled the group for about 20 hours in about 250g of the compound in a supersaturated solution. When all the ferrous (iron) material had dissolved into salts, I removed the head and found that the solids (salts from the chemical reaction) had caked hard on the group. It took me about an hour to scrape and wash them off and the result is in photographs below.

As a shortcut, I attempted to boil the head in citric and malic acid. This not only did not work but as the acid boiled away and became concentrated it caused a short circuit in the boiler element.* I WAS STANDING OVER THE BOILER WHEN IT BLEW IN A FLASH OF FLAME. *If the short had occurred above the level of the solution it would have blown hot acid from the container up into my face. Fortunately, the level of the acid had boiled away below the level of the short in the element, so this did not happen. I count myself lucky! The boiler was expendable, but my eyes and facial skin are not.

The group was also stripped of chrome. I've ended up with a viable group, but at a cost. It's not worth the time spent scraping of the caked-on deposits with a wire brush. Also, unless you've got access to cheap electroplating, its not going to be worthwhile getting it re-chromed.

An interesting experiment then, but not really commercially viable as part of a business process against the cost of acquiring a second-hand group by scrapping another machine for parts. *It's also bloody dangerous without proper equipment.* I fully intend building a scrapyard Gaggia Classic using cosmetically damaged components I can't sell on, but nonetheless form a machine capable of making decent coffee! This will be my backup machine .


----------



## ooglewoogle (Oct 2, 2018)

Cool! 😀 Also, you complete fucking mentalist. 😬


----------



## phario (May 7, 2017)

Randleog said:


> So, I completed the exercise, boiling the group in a solution of Alum, and the result is below.
> 
> A few caveats: it is a dangerous business. I boiled the group for about 20 hours in about 250g of the compound in a supersaturated solution. When all the ferrous (iron) material had dissolved into salts, I removed the head and found that the solids (salts from the chemical reaction) had caked hard on the group. It took me about an hour to scrape and wash them off and the result is in photographs below.
> 
> ...


 Thank you for being the experimentalist!

It's worth noting that, from what I understand, the grouphead is really the most expensive component of the entire machine (except the case?). I'm on my phone right now so unable to look it up.


----------



## MartinB (May 8, 2011)

Will have a spare no doubt. Feel free to shoot me a PM!


----------



## bargi (May 7, 2020)

You probably don't want to see my solution was....

https://www.coffeeforums.co.uk/topic/55155-stripped-bolt/?do=embed&comment=783694&embedComment=783694&embedDo=findComment


----------



## Rizwan R (Nov 28, 2020)

MartinB said:


> Probably got a spare group head should you require one!


 How much for the spare head


----------



## AndyDClements (Aug 29, 2016)

If Martin doesn't have one then there's one on eBay but as I don't know the seller and the image included doesn't show the ports it may not be a 3-port as we'd hope.

https://www.ebay.co.uk/itm/Gaggia-Classic-Boiler-Spares/333800666499?hash=item4db811f583:g:t5QAAOSw6qhfvQ7W


----------



## 2cups (May 6, 2019)

Just catching up on this. I must say I'm impressed @Randleog by your dedication to salvaging these parts, and also your utter disregard for health and safety! Glad you completed the exercise without a trip to A&E 😀 Did you manage to get the machine re-built in the end?


----------



## allikat (Jan 27, 2020)

AndyDClements said:


> If Martin doesn't have one then there's one on eBay but as I don't know the seller and the image included doesn't show the ports it may not be a 3-port as we'd hope.
> 
> https://www.ebay.co.uk/itm/Gaggia-Classic-Boiler-Spares/333800666499?hash=item4db811f583:g:t5QAAOSw6qhfvQ7W


 Well, assuming that the steam arm came from the same machine, it's either a Classic, Coffee Deluxe or Selecta. Not sure on the Selecta, but the Coffee Deluxe only has OPV ports drilled. And the shot I've seen of the insides of the Selecta imply it has the same internals as the Coffee...


----------

