Shots suddenly started blowing out

Beginner and pro baristas share tips and tricks for making espresso.

#1: Post by Benos »

I put this up in case it helps anyone with this issue.

Equipment: ECM Synchronika w/flow control / Baratza Forte.

I've been at home espresso for 15 years, and I am a freak-show in the quality control, consistency department.

Starting suddenly, for the last couple months, most of the shots are blowing out. Watching the bottomless portafilter, the shots that don't totally blow out look like they are struggling not to.

I've been using the same roasted beans for the last 10 years, which I get from a local roaster, so the beans are always fairly fresh.

And this is interesting, although I can't see how it is related. Right about when the shots starting blowing, I began home roasting. Most home roasted shots were blowing out... so I thought the blowouts were related to not having the roasting process dialed in. But when I pulled shots with the roasted beans I have been buying for years, they blew out equally.

I keep the pressure on the machine, with a blind portafilter, real close to 10 bars. Which is where it was when I got the ECM, and for the first 6 months, or so, to when the shots started blowing out, I was pulling the most consistent, tastiest shots ever.

I backflush at the end of each day, and at the first of each month clean the grinder with Cafiza.

By now I have every process of the grinding / packing / shot pulling process down to a science, and I have not changed anything in many months. So why shots are now blowing out is a mystery.

On a whim, I decided to recalibrate the Forte. Turns out the 2mm recalibration screw-and I'm guessing whatever it is attached to-is missing. I've made several repairs to that grinder over the years, so I ordered a new one, a Compak K3 Touch.

In the meantime, by using the flow control on the ECM-and grinding super fine-I can almost save the shots by keeping the brew pressure down to 8 - 8.5 bars.

I'll let you know if I am back in business when the new grinder arrives. (Should be in 1 - 2 weeks, according to Majesty Coffee.)

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#2: Post by Nunas »

Can you post a video?

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#3: Post by cafeIKE »

Ever rebuilt the group?

Benos (original poster)

#4: Post by Benos (original poster) »

The ECM is only about 6 months old.

Benos (original poster)

#5: Post by Benos (original poster) »

I took a video (mp4) but can't figure out how to post it, yet.

Benos (original poster)

#6: Post by Benos (original poster) »

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#7: Post by Nunas »

Wow, that's some gusher. Are you measuring the output; I'm guessing that there was way more than 1:2 (i.e., 18 g in, 36 g out)? I see two things. First, I think the grind's too coarse. Second, I see evidence of channeling and/or poor sidewall seal, which could be related to poor puck preparation. Of course, these could be related to the grind. Really stale coffee could do this too.

So, I suggest you grind finer as the first step. Don't worry if your shots are taking a bit too long compared to the 25/35 second 'rule'. It's more important to get a nice even flow and a good taste than to adhere to some arbitrary standard. If grinding finer does not fix it all, then you might try stirring your grinds with a needle before tamping. Finally, if there are still some problems, especially side-channeling, try the compass rose tamping technique. That is, once you've got the puck tamped about half way, and dead level, bear down a bit more on the tamper and slightly rock it N/S, E/W a few times, slowly increasing the pressure. Be sure to end dead level. IMHO, a level puck is the most important part of the prep process.

BTW, I don't think this is likely to be an issue with your espresso machine. If there is a mechanical issue, it would be the grinder.

Benos (original poster)

#8: Post by Benos (original poster) »

Thanks Nunas. I have tested everything that could be possibly tested with what I have. I will hopefully report back with happiness when the new grinder arrives.


#9: Post by zefkir »

Try with grounds from your local roaster to compare.

I've pulled shots just as fast but much cleaner. I would also check ground distribution within the puck. Deep, bottom to top WDT with the proper tool*, followed by small vertical tap and level tamp is by far the most reliable way to ensure that.

*9 acupuncture needles in a 3D printed handle available in a number of Etsy shops

Spurts like that can also be caused by particles stuck in the holes of your basket. If you grind near the size of the basket holes that can happen a lot more often, especially when the ground distribution in the puck is uneven.

Benos (original poster)

#10: Post by Benos (original poster) »

The sad news.... with the new Compak Touch, the blowouts are even worse. :(
The ECM brew pressure is set to 9.5 bars.
No matter how fine I set the grind... down to the point of serious clumping as they come out of the grinder, the shots spray all over the place... and the pressure at the grouphead only goes up to 2 - 3 bars.
With the Baratza Forte, I can set the grind to a little finer than "normal" and the ECM will pull an almost decent shot at 8.5 bars.
Do you think there could be any connection between the blowout issue and this post:
ECM Synchronika OPV will not stay adjusted
It doesn't seem to me that there could be, because the water volume and pressure at the brewhead are consistent.