# Bezzera BZ02 rebuild



## gdurham (Mar 18, 2015)

Hello all,

I recently purchased a BZ02s (2002) and it looks like it has seen better days. I pulled the boiler out of the unit and removed the element. I would like to soak everything in citric acid, however I am unable to remove the group head (chrome). Is this okay to soak still? What is the proper way to clean the HX? What gaskets are recommended to be replaced? I know that I need to replace the group head gasket and the gasket between the boiler and element. Any others I should order, please let me know and Ill get them going. Once this is done, I would ideally do a flush of everything. Is there a recommended way to clean the chromed components? I.e. hot water dispenser, group head, and frothing wand.

Thanks!

Greg


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## Dylan (Dec 5, 2011)

Others here recommend against soaking the Chrome group head in citric, I soaked mine for a couple of days in citric and it didn't seem to damage it or remove the chrome, but I was getting it de-chromed so I had nothing to worry about.

If possible, block the exit holes of the group head and only use citric on the inside, as you are safer this way.

The bolero actually does't look too bad, a lot of tear downs on here have taken apart the boiler to find buckets of scale inside.


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## gdurham (Mar 18, 2015)

So, what i can do is block the holes of the boiler and the hole on the group head. Fill both with the citric acid solution, and this way it will clean the inner workings go the group head and the inner workings of the boiler. Hopefully i understood that correctly









Can I do something similar for the heat exchanger? Fill it with the citric acid solution and let it sit for a couple hours?

Finally, are there any recommended ways to clean the chrome'd components safely? And any recommended seals to replace while I have the machine in a torn apart state. Thank you for all your assistance!

-Greg


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## JohnPrime (Nov 2, 2014)

Hi Greg, doing a nice job there.

Here's my BZ02s refurb thread.

What's the problem with getting the group head off? Is it the caphead screws that are stuck? When I did mine I found them to be really tight. I was loath just to use a big socket handle so I unscrewed them with a battery screwdriver on a low torque setting. There's much less impulse (mathematically torque x time) using an impact driver. If you have or can borrow one of the little battery impact drivers even better: the job should be easy. The worst that can happen is stripping the threads and having to helicoil or re-bore them, which is no biggy in the greater scheme. Be careful with the citric acid if it's in danger of getting near threaded holes in copper. I sealed mine with hot-melt glue to protect them.

Re seals. I just replaced all of them.

Good luck with the refurb. It's a cracking machine built like a tank


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## Dylan (Dec 5, 2011)

Yea, I did my boiler that way, removed it, blocked up all the holes and then filled it with citric. You could likely do the same thing with anything other part. My boiler took a 72 hour soak to get it properly clean.

John - I can't see how citric will damage a thread?


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## JohnPrime (Nov 2, 2014)

Dylan said:


> John - I can't see how citric will damage a thread?


If you're aggressive enough with the citric (I was, at first) it will. You'll knock off first the peaks then progressively more of the thread. You turn it into copper(II) citrate and you're left with a sort of wobbly drill-hole instead of a female thread. Admittedly I had it all heated to 40°C


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## gdurham (Mar 18, 2015)

Thanks for all of the information! JohnPrime, do you have a list of seal locations by any chance? The diagrams I have for this machine don't do a very good job pointing out what seals there are, so I can get them all done at once.

Thanks!

Greg


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## gdurham (Mar 18, 2015)

Also, how did you end up cleaning the group head once you removed it from the boiler plate?


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## JohnPrime (Nov 2, 2014)

You're welcome! There's a full parts pdf somewhere on the interweb, so I just followed that. Found it here.

It wasn't easy to find suppliers, though. Principally I used espressoXXL.de for the stuff that I couldn't get at the usual UK suppliers.

The group head wasn't that bad tbh. I think a bit of oven cleaner (the stuff with caustic soda in it) got rid of most of the crud. You've just got to be careful if you're using any scrapers not to damage any mating surfaces.

HTH

J


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## gdurham (Mar 18, 2015)

Got it descaling, thanks for the tips! In regards to the group head, once i remove it, I can just clean it with oven cleaner? Is there anything safe to soak it in?

Hopefully I can get the seals I need in the next few days and have it back together and start pulling shots.

Do you have any tips for pulling shots with this machine? Thanks again for everything!

-Greg


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## gdurham (Mar 18, 2015)

Thanks johnprime for the suggestion of using an impact driver to get those bolts out of the group head. Popped them right out. I'll upload a few pics of the cleaned up boiler and heating element. Wondering if I should go through any further or if it is worth getting it hooked up and doing a de scale at that point pumping water through the entire system. Thanks again everyone!


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## Dylan (Dec 5, 2011)

JohnPrime said:


> If you're aggressive enough with the citric (I was, at first) it will. You'll knock off first the peaks then progressively more of the thread. You turn it into copper(II) citrate and you're left with a sort of wobbly drill-hole instead of a female thread. Admittedly I had it all heated to 40°C


Good to know, I didn't notice this at all with any of the bits in mine, and I used a sting solution, but worth being aware of!


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## JohnPrime (Nov 2, 2014)

gdurham said:


> Thanks johnprime for the suggestion of using an impact driver to get those bolts out of the group head.


It's surprisingly effective, isn't it? I've just rebuilt an old Land Rover under the careful supervision of somone who knows what he's doing, and that was one of the things I learned.

Re: How to brew. The main thing to remember is that these are HX machines and they do need a cooling flush before brewing. There's a thread on coffeegeek with 40 pages of bedtime reading here, all about Bezzeras with a fair bit on BZ99 and Livia 90 which are pretty much BZ02s with a nicer frock. ISTR someone doing some temperature logging and the conclusion was that a 6-8 second flush (including the steam/water dance at the beginning) is about right. Adjust with experience, obvs.

Also the shower screen is relatively low wrt the group gasket: essentially it invades the space in the portafilter a bit, so you might not get 18g in an 18g basket, for example. I read somewhere that you need 2mm space between the top of the dry puck and the shower screen. You can test this with a 2p piece placed on the puck. It should barely indent the puck with the PF fully home. I find I usually have 14-16g in a 18g VST. YMMV.



Dylan said:


> worth being aware of!


I looked up the chemistry. It's very complicated and soon got way beyond my understanding. The upshot is that it's very unlikely to do any major damage unless you soak in hot, concentrated citric for a long time.


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## gdurham (Mar 18, 2015)

Here is what the boiler looks like after spending the evening with the solution soaking in, looks so much cleaner its amazing. Thinking about pulling apart the valves and soaking them as well and get everything nice and clean!


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