Hi all

I recently did a thorough overhaul of my simonelli Musica and repaired a whole lot of stuff. Most notably:
- new rubber for gasket and entire steaming system (piston, pipe, nozzle)
- new expansion valve on the group head
- new anti-suction valve on the boiler

Sealed everything with Teflon tape where necessary.
Everything went great for about 2 months.

The problem I'm having now is, whenever I'm flushing the group head, every now and then I hear some kind of "pssshhhhhh" sound, as if the water that's being dispensed is also drawing air. This wouldn't be a huge concern, if it didn't mess up my espresso.

Every now and then, when I engage my portafilter and draw a shot, it cuts off after about 7 seconds. Interestingly enough, not a single drip of espresso was delivered. Normally, the first drop comes out after about 3-4 seconds. If I re-dispense water, then the timing checks out again (first drip after about 3 seconds, shot takes around 25 seconds), but the espresso is very not good: no body, no texture, watery consistency.

I suspect the reason for this malfunction is because the machine is pushing air through the puck instead of water. As air is compressible, the flow meter is probably going nuts and thinks it already dispensed enough "water" and cuts off the shot (after 7 seconds already).

My question: where is this air coming from? Is it entering the group head due to a bad seal on the expansion valve/garbage collector? Or is it entering even before that? Where is the flow meter located? How does it work?

I have investigated the issue. I think it might be the solenoid valve, but I can't be sure.

I have found that the coil support of the solenoid valve (see image attached) can't be tightened completely, as the screw thread rotates along with the screw. Is this normal? The coil support appears to be made out of 2 parts: one containing the hexagon nut pointing towards the grouphead (part 1 in image), and another part with the screw thread that dispenses water towards the garbage collector (part 2 in image). Both parts look as if they are supposed to be a singular part, but when i tighten the screw on the right of the solenoid valve (the screw around part 2), part 2 rotates independently of part 1. Is this normal? It does not feel right. It looks as if the place where they connect (denoted with arrow and number 3 on the picture) should not allow for rotation. If this is indeed the faulty part, then it is possible that this is where the air comes from. Can anyone please verify?

Much thanks in advance
Bjorge

Firstly, you're correct that that threaded section of the three-way valve should not rotate in the shaft. It is a press-fit joint and should hold tightly. However, That is up at the drain-port end of the valve, the drain port end of that valve is open to atmosphere (the back-flush drain) while the machine is idle and subject to brewing pressure when the machine is brewing, never would it draw a partial vacuum and allow air into the brew circuit. Be ready to replace it soon, if it's falling apart, it isn't going to get better.

Second, I'll take a guess at your issue being a leakage outward from your brew circuit while idling. The water in there is above boiling temperature, if not maintained under pressure it will boil, the steam will continuously expand and te water will be continuously displaced from the circuit through any leak possible.

1: Brew Valve leaking. The drain-port end of your brew valve is less than perfect, maybe the plunger inside isn't perfect either. If the brew circuit water is leaking over the brew valve you might see drops from the drain valve or dampness or steam from the shower screen while idling.

2: Check Valve. I don't know for sure where the Musica's brew-circuit check valve is, but if it's leaking internally (allowing flow in the checked direction) then the brew circuit water is going to escape over your priming valve or back through the idle pump. This may be obvious if you notice that the pump outlet is terribly hot.

3: Expansion Valve. If the brew circuit water is constantly leaking over the expansion valve (not the normal allowance after 12+ Bar, but constant leakage regardless of pressure) then eventually the brew circuit will have nothing but steam in the upper half.

Once the machine has idled long enough for it to be half liquid water and half steam, the machine will blast that steam through the grouphead for several seconds ruining your coffee until the machine has displaced all the steam and liquid water has filled the circuit. I think this sounds very much like your issue.

Because your brew valve is already known to be loose at the one end, I suspect it. You may want to replace it first if the leak isn't obviously from somewhere else.

Hi JRising

Thanks so much for helping me out. I'm quite new to espresso machine maintenance. I truly appreciate you running things by me.

The brew valve (I suspect this is the same as "3-way solenoid valve") is indeed a tad worn out (Below i provided pics of the plunger and the valve). I suspect both are Parker valves. I'm about to order a Lucifer valve with ruby seal from bluestarcoffee.eu, which they believe to be more durable, and more suited for hard water areas (I live in a hard water city; I do filter my water with a Brita, but unsure how well this solves the problem).

I believe it is most likely problem 2: leakage in the brew valve. I replaced the expansion valve not so long ago and tightly sealed it with loctite 55. I do not know what the check valve is though. The shower head indeed drips every now and then when idle. I'll replace the brew valve and post an update. Thanks for the advice!

Bjorge

From your most recent post, including that you see some moisture at group evenwhen idle, I think your new 3-way solenoid Lucifer will solve it completely. Good luck and let us know the result.

JRising you are a genius
this is exactly what i'm facing
glad to see your reply
thank you

Thanks for your answer. I installed a brand new solenoid valve (including new piston new brass thing that goes against the group head, new magnet and all). Sadly, it didn't help
The Musica still dispenses air. I've attached a video below of the problem. What else could be the issue? Non-airtight overpressure valve on the group head? Something in the pipes behind the group head?

It's worth noting this problem only presents itself after sitting idle for a while. Pulling a shot right when it's warmed up works fine. It also starts dispensing water after having pushed out the air.

Another note: when inserting a portafilter with a closed basket and pressurising the chamber, the garbage collector works fine as long as the chamber isn't pressurised all the way. If I cut off the shot early, it depressurizes through the garbage collector. If I let the chamber pressurise all the way (like a couple of seconds of having the valve open) and I cut it off then, the garbage collector does nothing and the chamber remains pressurised. I have to disengage the portafilter, and as soon as the pressure in the basket drops a little bit, only *then* does the rest of the water flow through the garbage collector.

I have disassembled almost my entire machine (didn't open up the boiler, nor heating elements or small valves at the top; I did disassemble all the pipes on the left completely), took the opportunity to clean the pipes a bit with vinegar, cleaned the threads and applied new loctite 55 on every thread that required it.

Still, the Musica dispenses steam. I tried te-installing the old expansion valve (since the problem arose around the time I installed the new one), with new loctite as well. Still dispensing steam.

At this point, I'm out of ideas. The only pipes I haven't touched are the one at the bottom of the group head, and the one coming from the sirai pressure stat.

Am I just really bad at applying loctite? Am I missing something? Should I have went for PTFE tape like the owner before me? Should I just accept the machine is worn out and can't be fixed?

Is it simply overheating?

I thought the Musica was a heat exchanger machine, I don't know the NS machines well at all, though. That just looks like a long, but successful cooling flush in the video, to me. It doesn't look like the boiler water has been mostly displaced. There's still plenty of liquid recondensing on the showerface in the video, just plenty of steam with it because the superheated water coming through is going to flash to steam when it passes its final pressure drop, it's at boiling temperature and finally back in atmospheric pressure where it can expand. I get the impression from the first few seconds of that video that the boiler is probably higher than 120C, but that's only comparing it to ECM or Rocket machines in my mind.


Correct me if I'm wrong, if that machine is a dual-boiler and the brew boiler isn't significantly over 100C.

Hi JRising

Once again, thanks for helping me out.

The machine is indeed an HX, and brew temp is likely to be high. The boiler was set to 1.5 bars (above atmospheric pressure), which yields quite high brew temperature. I've lowered it to about 1.2 bars (the recommended range appears to be 1-1.5 bars), and I provided a video of catching the water in a preheated pitcher with a thermometer below.

Of course, my little experiment is very lacking, as the water will have cooled down quite a bit by the time it hits the pitcher with the thermometer. I can't immediately think of a way to do it better for now; I don't have a scace device or any other portafilter thermometers.

The steam hits temperatures of 80°C and above, but after letting it run, it ends up stabilising around 77°C in the pitcher, the three times I tested. If I can assume that this is the "temperature in the cup", i.e. about the same temp my espresso would have, is this a realistic temperature?

I feel like the steam is less extreme than before, but it's far from absent. Is this normal behaviour? Because I would think that the steam could be due to the fact that there is no portafilter engaged, so the pressure drops significantly, and the pressure in the portafilter might prevent the water from evaporating when you would actually be pulling a shot.