The easiest way to check an E-61 machine for scale build-up is to remove the gicleur chamber nut and mushroom and do a visual inspection of both the removed parts and the internals of the grouphead which are now before your eyes.

Tools Needed: (a) 7/8" or 22 mm or 8" Crescent wrench for the gicleur chamber nut; (b) 1-7/16" or 36 mm or 12" Crescent wrench for the mushroom nut; (c) needle nose pliers; (d) electrical tape for wrench openings. Note that some 12" Crescent wrenches may not have a large enough jaw opening to fit the mushroom nut - measure before you buy.


If you are working with a Vibiemme machine, you do not need the larger wrench for the mushroom nut but will need a 5 mm allen head wrench to remove the hex bolts which hold the mushroom in place. Apply some electrical tape or the equivalent to the wrench openings.


Start by having the machine off, unplugged, and, preferably, at room temperature. Apply a "counter-hold" to the mushroom nut using the 36 mm wrench and remove the gicleur chamber nut with your 22 mm wrench. The stainless steel gicleur filter screen may or may not come off with the nut. It doesn't matter - use the needle nose pliers or your thin fingers if it stays with the grouphead.


End of Part I - stay tuned for Part II.

Now remove the "mushroom" using a 36 mm wrench.

The scale buildup on the mushroom AND the walls of the mushroom chamber are good indicators of scale buildup on the internal surfaces of the hx.

The mushroom chamber walls have an area of about 10.5 square inches and, along with the hx surfaces, can effect the rate at which the machine recovers after making an espresso drink. I have soaked my entire mushroom in simple white vinegar many times and hence the scale buildup for this particular photo shoot is zilch but you can easily see what it looks like when it is clean.


End of Part II - Stay tuned for Part III

After you remove the mushroom assembly, remove the brew valve spring and brew valve using needle nose pliers. Soak all of these parts in descaling solution or white vinegar for about thirty minutes and then rinse all parts under running water, cleaning the mushroom with a green "scrubby".

I poured some white vinegar or descaling solution into the chamber with a blind basket in place and the brew lever in the brew position (this ensures that the drain valve is closed). I let this soak for about 30 minutes and used a toothbrush on the mushroom chamber walls. The result is as shown after draining the solution.


Re-Assembly:

Ensure that the mushroom assembly is rinsed well and that all of the small holes are clear by holding the mushroom up to a light source. There are four holes which feed the gicleur chamber and then, of course, the 0.70 mm gicleur (typical) itself.

With the brew lever in the exhaust position (all the way down), plop the brew valve in place and place the spring over the brew valve. Now screw the mushroom into place hand tight. Tighten with the 36 mm wrench - just snug - maybe 1/12 of a turn maximum.

Place the gicleur screen over the gicleur itself and screw the gicleur chamber nut in place hand-tight. Tighten with the 22 mm wrench - just snug - maybe a little over 1/12 turn.

Flush the machine well - maybe for about 5 minutes - remembering to not run the pump for over 30 seconds or so before giving it a rest for a similar period of time.

This is not meant to be a descaling procedure but the methods proposed will certainly remove a goodly portion of scale (if present) from the areas mentioned. Once you do this (and I can understand the trepidation), you will wonder why it took so many words to describe a simple procedure.

Nice post. Let me add one thing that experience has taught me. If you have a plumbed in machine, turn off the water. Otherwise you will need to mop your floor when you remove the group bolt.

Thank you for such a wonderful instruction, it made the process a lot less intimidating. It was nice to see that after almost 2 years of using softened water the scale was almost nonexistent. The hardest part of the whole procedure was getting the mushroom threaded back in against the pressure of the spring and then worrying if I wasn't damaging the threads.

Thanks for the tips. I had a pretty bad case, b/c of ignorance of descaling procedures and water hardness. I was using the test strips and thought my water was very soft.

Is the bronze like color normal after using the white vinegar solution for cleaning ? ( I guess the finish was taken off by the chemical reaction?)

picture: over a year use and some bad scale build up. per this post, soaked mushroom in white vinegar 30 mins then scrubbed off scale

I am NOT a plating expert but I do believe the 'mushroom" was subjected to nickel plating (the "silvery" appearance) but not the chrome deposition as were all of the visible parts of the E-61 grouphead. The bronze like color is simply the native naval brass that the part is machined from.

Scale buildup on the mushroom, lacking any documented evidence to the contrary, is INDICATIVE of scale buildup throughout the remaining surfaces of the hx loop.

You did remove the top nut that hides the gicleur and gicleur screen/filter ??

Yes I removed the top nut and screen and spring as well. All soaked in vinegar and cleaned. I also forgot to mention, I am doing this routine as a precursor to a full blown HX and boiler descale session. I thought your article was a great thing to do to get the bulk stuff out.

Thanks.