Repair La Marzocco bolt-on group by brazing to boiler?

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NickA
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Joined: 16 years ago

#1: Post by NickA »

Is it possible to repair an old-style La Marzocco bolt-on grouphead that is leaking by brazing it to the boiler? The older groupheads seem to be brass, and the boiler is stainless, so normal welding isn't an option. I was thinkg one might need to build up the bolt holes so that you were left with the rectangular outer footprint of the grouphead which would be easier to braze.

By all accounts repairing an old bolt-on grouphead that is leaking by replacing the gaskets is a bit of a hit and miss affair, so I was wondering if anyone had attempted this?

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Paul_Pratt
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#2: Post by Paul_Pratt »

Probably best not to do it. Which boiler do you have? is it the one with the studs on the boiler or the one with the 8 holes in the boiler?

If it's the latter there are some great green viton gaskets available now that work very well.

Or get a new boiler steel and you can upgrade the whole system as well.

NickA (original poster)
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#3: Post by NickA (original poster) »

It's the one with the 8 holes, so I'll try the gaskets as you say.

"Or get a new boiler steel and you can upgrade the whole system as well."

What is a boiler steel? Stainless steel groups? Wouldn't mind, but I've been quoted $3300 for a 3 group boiler here in New Zealand, so I'll have to pass on that.

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Paul_Pratt
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#4: Post by Paul_Pratt »

Sorry I meant steel boiler with steel groups. If you have the 8 hole boiler you only have the choice of paper gaskets, the viton is only for the boilers after yours (the ones with the welded studs).

Paul

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Rosscopico0
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#5: Post by Rosscopico0 »

Paul, do you know what sort of sealant to use with the paper gasket on the 8 hole boilers?

Bummer the green viton gaskets cant be used :cry:

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erics
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#6: Post by erics »

Equally important to the type of sealant is the torque value (dry or lubricated), torque procedure (pattern), and re-torquing procedure for this machine. I could guess but something tells me Paul P. (amoungst others) knows the correct answer.

And all of the above assumes that there are no unreasonable irregularities between the mating surfaces.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

NickA (original poster)
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#7: Post by NickA (original poster) »

Hi Paul, could you outline a suitable torquing procedure?

Also there is mention of a pressure testing procedure that needs to be performed if changes have been made toe the boiler (welding or grouphead seal replacement; can anyone outline this as well?

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eastpresso
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#8: Post by eastpresso replying to NickA »

Either this is a common question or Paul can read minds :wink:

NickA (original poster)
Posts: 184
Joined: 16 years ago

#9: Post by NickA (original poster) »

Wow; excellent page on reassembling a La Marzocco Paul, and thanks eastpresso for pointing me to it. I had just looked at the tear down sequence of the GS1 rebuild on Paul's site, but hadn't found this section.

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mhoy
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#10: Post by mhoy »

OMG that looks to be a complex tricky rebuild. Good luck!

Mark

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