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Rancilio S20 three-way solenoid leaks when running either group head

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Discussions > Espresso > Machines > Rancilio S20...

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tsruhnke
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Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Mon Jun 4, 2012, 2:33pm Subject: Rancilio S20 three-way solenoid leaks when running either group head

Hello All! I recently completely descaled my Rancilio S20 and it is working much better but the group heads still have low pressure and leak during the entire brew process out of the backflush/ 3-way solenoid at the same volume as the group head itself. It also makes an extremely loud buzzing/electrical pump noise when I try to pull shots. I have attached a picture of the leak and appreciate any advice on solving this issue! Thanks! (Click for larger image)

tracerbullet
Senior Member

Joined: 13 Feb 2012
Posts: 157
Location: Saint Paul
Expertise: I love coffee

Posted Tue Jun 5, 2012, 7:24am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

I'm only familiar with Gaggia home machines but when it comes down to it all machines seem to be similar in function. Since no one else has replied I'll see if I can give you a few ideas: 1) Unlikely but possible - Is this part of the overflow path? The pump will put out a higher pressure than an OPV (assuming you have an OPV, a bypass pressure regulator). That bypass has to go somewhere, to the water reservoir or perhaps right back to the pump. I guess I'm saying - depending on the plumbing path of your machine it's possible this is supposed to flow water at this time? Again this is unlikely but it's worth asking. 2) If it's a dump-off pressure release after the shot, like the stuff I'm used to, to release pressure off the puck so you don't spray coffee everywhere when you remove the portafilter - then it's simply not closing all the way. I guess this is most likely here. In that case solenoids seem to all be the same. The black plastic piece with the wires is the actual solenoid, its a coil that gets electricity sent through it. You'll likely find a single thin nut holding it to the valve. You can remove that nut and pull the solenoid from the valve. At that point normally the valve itself has a nut cast into its body, and you can remove the valve from the boiler (or remove it from whatever it goes into which is attached to the boiler). Do it slowly as there are parts inside... Inside you'll see a plunger with a rubber tip and a spring. For some reason that tip may not be sealing. Could be that the rubber is worn out, become very hard, or the opposite and has disintegrated. Could be that there's debris or scale in there keeping it from closing. Could be that the whole thing is full of scale and just not able to move freely. I'd disassemble it, it's fairly easy. Open it up slowly and have a look inside and see what's keeping it from closing. Hope that helps... I don't have this machine and haven't worked on one but maybe that gives some ideas if nothing else?

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Tue Jun 5, 2012, 8:08am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

It does have an OPV on top of the boiler (descaled) which has a slow steam leak so I'm guessing the pressure is a bit too high which I will need to address. I believe this may be causing a switch to be flipping off and killing the heating element after half a day? Not sure. (Pic attached of the switch). And it is the dump-off pressure / backflush, however it runs water continuously as I run the brew head. The brew heads both do the same thing, have way too little water come out of them to even consider pulling shots, and it makes an extremely loud noise when they are running (could be coming from the "flowmeters" that are on top of the heads and run to the copper lines of the brew heads at the boiler. I already disassembled the solenoid (along with the entire machine (first every rebuild attempt)) and descaled everything (group heads, valves, tubes, boiler) but the "plunger" and the spring which were grimey but seemed okay. The copper valves themselves were still a little dirty (black grime like grease) when I reassembled, but mostly clean and scale free. I have some pictures of before the machine was descaled at which time it pretty much acted exactly how it still is. Thank you for your response! (Click for larger image)

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Tue Jun 5, 2012, 8:10am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

Flowmeter (Click for larger image)

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Tue Jun 5, 2012, 8:12am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

Switch that flips off after hours (sometime in the night). and causes the element to make a louder electrical noise when it flips (Click for larger image)

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Tue Jun 5, 2012, 8:13am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

a closer view (Click for larger image)

tracerbullet
Senior Member

Joined: 13 Feb 2012
Posts: 157
Location: Saint Paul
Expertise: I love coffee

Posted Tue Jun 5, 2012, 10:57am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

You mentioned black / grimy, is there a chance that substance is the rubber tip of the plunger itself disintegrating? I recently helped my neighbor fix a solenoid on their frig that flowed water to the icemaker, and the whole time I kept thinking how similar it was to our coffee solenoids. It too had a black grime in it, which turned out to be the plunger rubber tip itself disintegrated. Well that's not the right word but - anyhow that's what the substance was. For them it kept the thing stuck closed. For you it might be enough of it missing that it can't seal? Is the tip a nice piece of rubber or is it maybe too soft and / or not completely there any more? If that all checks out is there chance that the wiring is wrong and it's being told to open when you really don't want it to be? Can you hear it click or feel it vibrate/ Or check it out with a multimeter to see if it's getting current? Just some random ideas, again not knowing your equipment at all.

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Wed Jun 6, 2012, 10:10am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

I took the valve apart again to check it and compared it to the images of new parts from the internet and all looks right. As I keep messing with the machine however, I am beginning to think it may have something to do with the pump. The machine sat for about 5 years before I began work on it and I have heard that the pumps are usually shot on them if they sit for more than a couple years. I didn't suspect this before because it filled the boiler just to its auto shutoff point just fine, however could it be that it just doesn't have the power to support water flow through the group heads? (This could also be the source of the extremely loud noise I was referring to, but it's impossible to be certain). I began taking the pump apart, which I hadn't done in my restoration process, and am stuck because I don't see any obvious issues with the exception of scale on a spring that came out of the side of it (and the two water hookups won't come off with any amount of force). I'm hoping it can be cleaned or oiled (the knob surrounded by the bearing is relatively stiff)? There are no leaks, pictures attached. (Click for larger image)

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Wed Jun 6, 2012, 10:11am Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

Pump motor (Click for larger image)

tsruhnke
Senior Member

Joined: 20 May 2012
Posts: 13
Location: Des Moines
Expertise: Pro Barista

Posted Wed Jun 6, 2012, 1:18pm Subject: Re: Rancilio S20 three-way solenoid leaks when running either group head

Well after further further testing I have concluded that it is in fact the solenoid on both sides that is making the ridiculously loud noise. I ran the head and it makes the noise. unplugged the wires from the solenoid and the pump runs silent and no noise (and water comes only from the solenoid obviously). I also tested just the solenoid with a screwdriver down the middle per an article that I found and it pulled on the screwdriver like it said it should so i believe it is functioning. And during this test it didnt make the noise. I also noticed that the pressure valve is varying insanely when brewing from a couple bars up to nine). I posted a video to youtube for a better visual: http://www.youtube.com/watch?v=rSwDY3wpQmw

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