Little to no extraction suddenly - all things equal (Gaggia Evolution/58mm)

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
DoppioRistrettoMan

#1: Post by DoppioRistrettoMan »

Hi, all,
New member but old dog. I am having a problem with a Gaggia and hoping for some suggestions. I'd like to give a brief history so you know where I fall experience-wise.

I've been an avid Third Wave espresso drinker and home-barista for the better part of 15-20years. I roast my own coffee or buy fresh-roasted, and when the planets align, I can pull a pretty tasty shot - usually 3 out of 4 times.

About 20 years ago, I picked up a Gaggia Evolution and Cunill (semi-commercial) grinder. As many of you probably know, the Evo is basically a Classic with a different shell. I pull fantastic and tasty shots (at least for my taste) - typically a double, restricted. They were yummy enough for me that I did not need to tinker, update, upgrade or replace anything, so this has been my set up for years.

About 5 years ago the Gaggia began to leak around the brew head, and I assumed it was the gasket, so I set it aside planning to repair it. Well, weeks turned into months turned into years (don't ask). Last year, with Covid keeping things boring, I decided to address my leakage. I replaced the brew head group gasket and I was right back in business for a while.

One day about 4 months ago, my water went cold. No hot water from either spout or steam wand. But I had power to the unit. I replaced, both, the brew stat and the steam stat with no luck. I spoke with Gaggia and they said that the thermal fuse could still be bad even though there is power going to it. I replaced the thermal fuse and...bam! I was back in business!

I have been pulling fantastic shots for last couple months. But this past week, a new problem occurred that is frustrating me.

Suddenly, I am getting little to no extraction from my shots. The grind has remained the same (maybe tweeked a hair depending on age of beans and humidity). My tamp is consistent because I use a distributor/tamper. But suddenly now, from the moment I turn the machine on til I stop, it just runs with no brew coming out for a good long while. After about 30 seconds (which is usually near the end of my pulls), I will start to get some liquid and by the time 45-60 seconds have gone by, I have maybe about a teaspoon of an awful tasting, over-extracted sink shot. WTF?

Has anyone experienced this on a home machine, particularly a Gaggia?

Like I said, I have adjusted the grind accordingly like I always have when pulling tasty shots, and my tamp is very consistent. So I am stumped.

Here is a link to a video of the current problem:
https://drive.google.com/file/d/1J0z2-Z ... sp=sharing

Here is a link to a video of a different (yummy) shot from 3 weeks ago using EXACTLY the same parameters:
https://drive.google.com/file/d/1cAGyRI ... sp=sharing

Any suggestions or advice is greatly appreciated!!!

Thanks in advance!
Ray

DoppioRistrettoMan (original poster)

#2: Post by DoppioRistrettoMan (original poster) »

Wow.
Such a helpful bunch.
Thank you for nothing.


Ms./Mr. Mod:
I have perused your confusing and cumbersome Help and FAQs and cannot find how to cancel my account.
Please feel free to delete me.
I will not return.
Ray

JRising

#3: Post by JRising »

It sounds like your boiler is starting from "Not full". You have many years experience with the machine so we'll assume you know to top up the boiler after steaming, so the possibility that the boiler is boiling off its water and letting it escape (possibly as steam) is my assumption.
If you open the steam valve immediately before brewing, do you get more than a few drops of water out of the wand? If the boiler were full, you should get several millilitres just due to the boiler being at boiling temp. If you get nothing but a drop and a thin hiss of steam, the boiler obviously isn't topped up.
Where might the boiler be leaking? Possibilities include backward toward the pump (if it has a priming valve, its own check valve may be shot). over the brew valve, if the showerface always seems damp even while the machine idles, this is worth looking into. Over the expansion valve, you may actually see this as movement in the clear hose after the machine is fully heated and sitting idle.