Breville Dual Boiler Mods and Maintenance - Page 90

Need help with equipment usage or want to share your latest discovery?

#891: Post by jaker »

Fixing some leaks on a recently acquired second-hand BES920.

Can anyone tell me what lies beneath these tube nut fittings? (my search attempts failed)

Are they the same type of seals used for the other locking pin fittings?

Also, any special techniques for removing the nuts - or just brute force?



#892: Post by BaristaBob » replying to jaker »

Are the tubes under the nut fittings actually leaking? Since Breville went to these, I haven't heard of anyone needing to fix a leak under the nut fittings.
Bob "hello darkness my old friend..I've come to drink you once again"


#893: Post by jaker » replying to BaristaBob »

Good question... In the past couple days, I'd seen tiny leaks (small bubbles coming up through nut) forming a small pool on top of the nut - but I just switched the machine on for a good 5 minutes and waited for the leaks and didn't see one.

I won't be changing anything I don't need to so shall continue to monitor.


#894: Post by iyayy »

luvmy40 wrote:How much coffee?

I have the occasional stuck puc. Not often, but it happens. I am using the stock baskets with the IMS precision screen and grind 16-18 g in the double.
just like to add,
i drink all roasts, dark, very light, etc. adjusting clearance with the breville tool down to .5~1.5mm actually helps, but some beans just get stuck more often, and some never did regardless of roasts.

also basket matters. my ims 22g on sticky beans sticks 90% of time. too polished hence less friction maybe?

vst 15g is 50/50, and usually adjustable to not stick. stock basket is least prone to stick.

i didnt find screen to make a difference, im using stock screen since ims screen sometimes spills water at edge. cant figure that out.

end of the day i just spend extra time cleaning the head if it sticks, but wiggling the portafiler can sometimes help dislodge the puck.


#895: Post by jasiano »

so the last day or so I have noticed the water flow from my BDB has been... uneven... took off the shower screen/disk to look at the part of the group where the water comes out and see this

that black part where the water comes out feels like a sort of plastic and something else compound, and it looks completely stuffed. Very bumpy and uneven, there are parts that look like it melted, the white parts are where the black colour paint(?) finish has come off when it wiped it with a cloth.

Is this a sign that it's just degraded and needs to be replaced because of wear and tear or is it 'normal'? Machine is only 15mths old and used regularly but also cleaned regularly (i.e. back flush daily, clean water run through a filter & softener because my local supply is quite hard, the shower screen and puck and PF basket get a soak in cafiza once a month and they are usually already pretty clean).

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#896: Post by bringyoutomyhell »

AFAIK that bubbling is "normal" and starts to happen to all BDBs after a few months of use. It shouldn't impact water distribution


#897: Post by DanyEss »

Hey Gentlemen,

I've been quite busy with my BDB (it is called Gastroback or sage here in Europe, badge engineering, though...)
So far I have mine equipped with rotary pump, plumbed to RO, additional needle valve for flow control and three way lever valve to by-pass it (full flow from pump).
So far I have also made some replacement parts for my machine (reversed engineering and CNC machining), but if someone interested I can make series of those.
I have following parts tested / available:

1. Shower screen disc - original is PTFE coated aluminium, mine is food grade stainless.
2. Portalfilter collar - machined from mitsubishi ertalon ( food grade)
3. PTFE gaskets for 3 way valve
4. Replacement Seal kit for stream wand

Here is the link to all pictures related to this build: ... jKRuyjvf50

If we can gather a good lot I might be able to book machining capacities and make pricing calculation.

Hit me up if interested.




#898: Post by jasiano »

bringyoutomyhell wrote:AFAIK that bubbling is "normal" and starts to happen to all BDBs after a few months of use. It shouldn't impact water distribution
Okay. It did seem odd, all other things equal the water flow suddenly started flowing different...
The black colouring came off a bit after I wiped it but now seems to have stopped flaking as well.

I'll just keep going with it :)

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#899: Post by bringyoutomyhell » replying to jasiano »

This came up on the espressoaf discord and every single one had it, so yeah I think one should just roll with it. It was there for you even weeks/months ago but you just didn't know it. So I don't think it's related to the change in flow anyway :D