# I am perplexed.



## nightslayer (May 29, 2016)

Gaggia Classic paired with a Nuova Simonelli MDX. Beans are from a local roastery (a plug for Silver Oak in Cambridgeshire - they are pretty fab), three weeks from roast (with the second week spent sitting in the freezer since I use my beans in two batches after I buy them one week post-roast). I pull a shot a day.

My routine is to preheat machine for an hour, then weigh 18.5g, grind (for those familiar with the Eureka/Simonelli settings, my grinder sits between settings 7-8.5 depending on lightness of bean and age) and thwack while grinding to reduce clumping. I then sweep out the chute, purge and sweep it out twice, then thwack some more, while tapping the doser to dislodge grounds held there by (discharging) static. I then tap the pf to distribute (a la Matt Perger), then tamp with sufficient pressure till the tamper is buried, twist with no pressure to polish, then lock in, and then pull.

The pull is done with an Auberins preinfusion PID, which runs the pump for 1s, stops for 2s, then runs the pump for 30s. I cut it off when the output hits 36g (so with drips it usually ends around 37).

So my problem - I am getting to the end of this bag. Yesterday I carried through my usual routine (grind setting for these beans: 8), and the machine, strangely, gave me 25g output in the full 30s (usually I get to 36g within 25-28s or so). So I figured I'd shift the grind to 7.5 or so for today. Today I also decided to scrub out my showerscreen and sponge down the surface of my shower head (didn't have allen keys handy to remove it), to remove quite a bit of oils which had accumulated.

Carried out the routine today, and the machine completely choked up. Tried again with the same grind figuring maybe somehow there had been retention in the grinder because I hadn't cleared out the doser sufficiently (though unlikely), choked again. Tried again with the grind at 7, still choked.

At that point I had run out of beans, so I tried it with a bunch of stale beans I had sitting around that someone gave me as a present, which generally tend to channel like crazy and require a higher grind. At 18.5/setting 7 the machine likewise choked. Tried it again at setting 6, and the stuff was just slowly dribbling out. Had to dial it down to setting 5.5 before I got the usual crazy spurts like I would expect to see.

So my question - what on earth could have happened in between a day to cause my machine to randomly choke up where all my settings are unchanged? I've got a pressure gauge on the Gaggia and output is reading 10 BAR as per normal.


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## mremanxx (Dec 30, 2014)

Only thing that I can suggest would be, check your 3 way valve is not venting into the drip tray, water taking the easy route once pressure in OPV is reached The other would be your pump failing, getting the pressure but flow is being reduced,

Many more on here with lots of experience with this machine, mine is limited I am afraid.


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## MediumRoastSteam (Jul 7, 2015)

Ages ago when I had my Classic I ran into a similar scenario. I changed "nothing" and my machine started to choke.

After a few perplexed days, I figured out what I did differently: For me, I had my machine on a timer, one that I had bought 10 years ago sort of thing. When I plugged the machine directly into the mains, the problem went away.

I am not saying that your problem is the same, but it is worth while isolating every single possible variable.

Hope you get to the bottom of this.


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## nightslayer (May 29, 2016)

Ah yes I was afraid it might be the pump - anyone knows what the indications of a failing pump are? I figured if it is outputting 10 bars then that variable shouldn't be an issue, correct?

Also, my machine is plugged directly into the mains; I have a timer which toggles the pump on and off (i.e. my PID) but I don't think that would affect anything would it?


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## MediumRoastSteam (Jul 7, 2015)

Can you grind coarser so that you kind of get an espresso-like shot in 30s? If that works, happy days, and don't worry about it. Now, you will need to isolate your variables to diagnose the problem, and that can take some time. If isolating the PID is a simple task, try it and see how it goes. Then move on to the next and keep going.


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## nightslayer (May 29, 2016)

Update: Grinding coarser seems to have solved the problem. But this is strange, since now my grind setting is sitting at 6.5 for a light-medium whereas previously it'd have been 7.5.. but fresh beans and a good 2oz of of espresso/crema for 36g which tastes just fine so I suppose all is alright with the world. Nonetheless - am still perplexed over how my grind setting could just have shifted by one? The Nuova Simonelli MDX is quite a tank so I doubt my tapping the doser to dislodge grounds should have affected it much?


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## MediumRoastSteam (Jul 7, 2015)

nightslayer said:


> Update: Grinding coarser seems to have solved the problem. But this is strange, since now my grind setting is sitting at 6.5 for a light-medium whereas previously it'd have been 7.5.. but fresh beans and a good 2oz of of espresso/crema for 36g which tastes just fine so I suppose all is alright with the world. Nonetheless - am still perplexed over how my grind setting could just have shifted by one? The Nuova Simonelli MDX is quite a tank so I doubt my tapping the doser to dislodge grounds should have affected it much?


I wouldn't lose any sleep over it. I suppose people can come up with a theory, but it's only a theory. 

Enjoy the coffee.


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## mremanxx (Dec 30, 2014)

Agree with above, if you are back to getting good coffee don't lose sleep, just drink good coffee


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## Josevonspain (Feb 27, 2017)

Haha totally


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## 4085 (Nov 23, 2012)

It is not unusual for beans s to need large adjustments as you get towards the end of the bag and they begin to stale. I often find this. It is the same if I put 250 gm into the hopper and forget to top it up. The lack of weight to push the beans through alters the grind coarseness quite considerably


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## nightslayer (May 29, 2016)

I am aware of that, but staling usually requires a finer grind - what these did is they went and choked my machine half to death when they were on their last legs. And I also single-dose, so my settings are based on single dosing. Also, the plot is now thickening (though also it seems, at least for now, to have come to a close) - so I bought a new batch of the beans, got a decent pour, albeit a couple seconds too fast, at about ~6.3 or so, and I thought that was that - my grinder had just magically shifted by one grind setting, but I was getting espresso and all was good.

The day after that I decided to up the fineness to ~6.7 to slow down the extraction - surpringly, I got an absolute gusher. And so now my grinder is again sitting at ~7.3 where it used to before that odd abberration explained above, and things seem to have returned to the status quo. What on earth?


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## dsc (Jun 7, 2013)

Variability in the beans inside the bag perhaps? I do agree you should be going finer not coarser with the beans aging, but perhaps the beans towards the lower part of the bag are different from what was in the top part? is this a blend or a single origin? I always wonder how roasteries make sure that beans in a blend are thoroughly mixed.

T.


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## Mrboots2u (May 10, 2013)

What size is your tamper again ?


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## Mrboots2u (May 10, 2013)

What size is your tamper again ?


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## destiny (Jun 4, 2015)

What is the flow like out of the group without a pf? Does it look normal or reduced?


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## nightslayer (May 29, 2016)

Strange; I thought I had replied. Anyhow, DSC - I use single origin beans!

Mr boots: I use a 57mm, though the issue here is the machine choking and not gushing, and for four pours in a row after months without a similar issue, so I doubt it would be edge channeling?

destiny: Flow seems alright, I'm not too sure what a reduced flow looks like! But given that I've just cleaned out the showerscreen surely the flow should be less restricted, if anything?


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## destiny (Jun 4, 2015)

Reason for asking was a possible blockage in the supply of water that look like choking.

While doing a shot have a look at opv tube and see how much water is sent back. Otherwise if you have a way of checking what opv is set to this would be my next suggestion.

Any chance it could be scale?


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