# Gaggia classic incredibly sour (yes it is a new problem)



## Chris1992 (Oct 3, 2016)

Hello everybody,

After lurking these forums for years I have finally met my match in a, for me, unsolvable problem.

It started with a no flow problem. I completely striped down the machine, opv, solenoid, boiler, the works. Got it back together it worked but the coffee didn't taste great. It got worse. My espresso's are so sour and I think I have tried everything.

First of I made pressure gauge on my portafilter and set my OPV low (currently just 7 bar).

This did not work.

Then I installed a pid to better monitor the temperature, I reckoned that the brew stat was shot. I'm still waiting on a pt100 rtd sensor from MrShades but in the meantime am using it with a k thermocouple which does work. But that didn't do the trick either.

I still feel like the flow is a bit to fast but I had my coffee ground really fine by a local coffee shop, finer than my grinder can go, and the pressure is as said really low. Still it seems fast and remains really sour.

My flatmates are mocking me and my unfruitful tinkering.

They are trying to get us to buy a nespresso machine, I don't want that.

Are there any suggestions, please!

Thanks in advance!!!


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## GCGlasgow (Jul 27, 2014)

What grinder are you using? Might be that which needs changed.


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## El carajillo (Mar 16, 2013)

As above Ref grinder. Is the grinder thoroughly clean ? are the burr's sharp ? no stale coffee buildup.

Shop ground coffee will stale very quickly (small grounds exposed to air =







.

Try increasing the temperature and let the shot run longer.


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## Obnic (Jan 14, 2014)

Chris1992 said:


> .....my coffee ground really fine by a local coffee shop, finer than my grinder can go, and the pressure is as said really low. Still it seems fast and remains really sour!!!


If you have a fine grind, your pressure is low and still the shot is gushing then you almost certainly have a wicked channeling problem (water finding a fast route through the puck so it is underextracting most of your coffee and overextracting a very small part).

This issue is primarily about how evenly you distribute the coffee in the portafilter before you tamp, and how level and flat your tamping is.

This issue will be aggravated if you use coffee that was ground a few days ago.

Search 'distribution' for all kinds of advice including WDT which may help.

I am assuming because you said you're using a thermocouple that you are extracting at 93-95c?


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## Robbo (Feb 17, 2016)

As above re- distribution but if still got same problem then most likely needs grinding finer.


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## Chris1992 (Oct 3, 2016)

Thanks for all the replies!

Well I tried a lot of different temperature settings. And I got my previous coffee from a shop around te corner where they grind themselves so the time between grinding and making wasn't long. I will definitely clean my own grinder. I stayed with my girlfriend this week and don't know the model and make of my grinder by heart







but I got it from a friend and it isn't much but it is a bur grinder. And I used to get good tasting coffee white this set up.

Thanks for the advice on channeling I will look in to that further but they way my coffee tastes at the moment is so extreemly sour. My mother owns a classic as well and buys preground she still tramps with the plastic tamper and her coffee is normal tasting. So I find it heard to believe that this level of sourness only stems from stale coffee.

I will continue on this quest and hope that I can figure this out.


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## MWJB (Feb 28, 2012)

Can you give us any info on your shot parameters (dose weight to 0.1g, beverage weight to 1g, shot time)? Sourness is usually underextraction, if you can't grind finer, try pulling longer (but weaker) shots.


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## Chris1992 (Oct 3, 2016)

Yes I'll report back with more information when I'm home. I will upload a film of an extraction here.

and again, thank you all for your suggestions


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## Chris1992 (Oct 3, 2016)

yes I will post a video of me preparing a shot this weekend or Monday. I am very excited to start with this but I'm not home yet.

thank you for all your replies.


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