# Sour espresso / low extraction



## the_partisan (Feb 29, 2016)

I've been trying to dial in my Gaggia Classic (post 2015) with the Kinu M47. Unfortunately not having the best luck. Using "stock" (it only comes with pressurised basket, I'm using an extra Gaggia basket)

0+7, 15gin , 45g out - seems like additional 10g of liquid comes out after I stop the shot, and leaves the puck very wet - tasted pretty sour, though somewhat drinkable.. measured extraction, was 15-16% or so. (unfortunately didn't have the syringe filters at hand, so this is unfiltered)

I tightened the grind to 0+6, 15g in, but this time grouphead was leaking water all around the basket, and had to abort the shot. I thought I tightened it reasonably, or so I thought. Should it need really hard tightening to pull an acceptable shot? Is it an temperature issue?


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## KingoftheHeath (Nov 22, 2019)

Have you checked the gasket?


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## the_partisan (Feb 29, 2016)

KingoftheHeath said:


> Have you checked the gasket?


 No, but the machine hasn't been used much. What should I check about it?


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## Dave double bean (Mar 31, 2020)

Check the gasket has been put in the right way up and the shower screen isn't too tight

The gasket has a rounded edge and a sharp edge, it's sharp edge facing the screen, even better order a new one and for yourself

Sent from my HD1913 using Tapatalk


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## the_partisan (Feb 29, 2016)

Is it a rule in thumb in general that the gasket shouldn't leak even if you grind very very fine?


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## BlackCatCoffee (Apr 11, 2017)

The most common reason for leaks is that the grouphead seal is dirty and has coffee on it preventing a proper seal. Perhaps check that.

As you say your machine is post 2015 I assume it is not the very latest Classic? As such it may not have a 3 way solenoid and you will likely experience 'soupy' pucks as the pressure is not relieved effectively.


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## Rob1 (Apr 9, 2015)

The gasket shouldn't leak at all. A leak could affect the max pressure.

What were the shot times?


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## the_partisan (Feb 29, 2016)

Something like 25-30 sec


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## the_partisan (Feb 29, 2016)

I tried removing the gasket, but it was not really possible - requires whole disassembly of the boiler unit which is extremely hard to reach. Seems like I would need disassemble EVERYTHING, including front panel etc.


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## KingoftheHeath (Nov 22, 2019)

There's a gasket in the group head - that's the one you need to get out


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## the_partisan (Feb 29, 2016)

KingoftheHeath said:


> There's a gasket in the group head - that's the one you need to get out


 Yes, I saw it but you can't get the group head out without removing the whole boiler.


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## KingoftheHeath (Nov 22, 2019)

Right I'm with you. I think it does come out without the disassembly but it takes some effort. YouTube should be your friend for a tutorial video. I recall just cutting it out in chunks when I had my Classic. Then replaced with a silicone one.


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## KingoftheHeath (Nov 22, 2019)

But your newer model might be different, if so then I'm afraid I don't have the answer


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## the_partisan (Feb 29, 2016)

Yes it's totally different, you need to disassamble/disconnect the whole unit basically to remove the gasket.


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## the_partisan (Feb 29, 2016)

While trying and failing to remove the boiler, and after putting it back I found this very small piece remaining out.. hmm, no idea what it does, though..


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## flyboy320 (Mar 9, 2020)

the_partisan said:


> While trying and failing to remove the boiler, and after putting it back I found this very small piece remaining out.. hmm, no idea what it does, though..


 I know you posted this a little over a month ago and have probably figured it out, but that's the clip that goes in the black steam knob. It holds the knob tight over the steam valve shaft.


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