Rancilio Silvia suddenly stopped making crema

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
thedude323
Posts: 1
Joined: 3 years ago

#1: Post by thedude323 »

Hello, I own a Rancilio Silvia with a meBarista PID. Yesterday it suddenly stopped making crema, it makes a very black, thin coffee that is more bitter / sour than usual and again, it has absolutely no crema.

I use the same coffee and parameters all the time so something changed and I cannot figure out what it is.

The grinder is a Nuova Simonelli and the grind setting hasn't changed.

I weight 16.8 - 17.2 gram of ground coffee for each double shot.

I weight 30-35g of coffee per double shot and it takes between 30-40 seconds to pour.

I do measure every shot I make because I have a scale on my coffee machine just for that purpose so those are actual measurement and not approximations.

I also use a bottomless portafilter so I can tell there is no channeling.

I connected my phone to the PID to make sure the settings were all fine and even changed some to make sure it was still responsive. Everything seemed fine. (Note: I changed settings to check the responsiveness, I reverted my changes afterwards). The settings are a 96 Celsius brew temp with a pre-infusion of 3s and 100% pump power.

The coffee temp in the cup was 71 Celsius which seems fine to me although I usually don't measure that.

I read that detergent residue on the cup could cause this so I even tried thoroughly rinsing a cup to be sure.

We always use the same coffee and this happened in the middle of a batch but just in case I went and bought fresh coffee. Same result.

I typically get very consistent results. None of my parameters have changed so I have no idea what is going on. I called a repair shop and his only guess was the pump losing power. But since it still flows at the same rate I'm not sure that make sense so before running out and changing the pump I would like a second opinion.

Thanks a lot !

slaughter
Posts: 89
Joined: 3 years ago

#2: Post by slaughter »

My guess is either the pump or scale in your water route. How is your water flow? I suggest to run a full cleaning procedure and check again

Marco_305
Posts: 2
Joined: 2 years ago

#3: Post by Marco_305 »

Hello, I have the same problem with my Silvia. I'm using it for more than 15 years. Suddenly the coffee is black. Taste is ok, but crema is missing. Nothing changed. Pump and electrovalve are ok. I'v checked it by changing parts with another Silvia. Water seems to be hot enough. Machine is cleaned. Any clues?

JRising
Team HB
Posts: 3664
Joined: 5 years ago

#4: Post by JRising »

Without seeing it, I would advise adjusting the grinder.
You have to dial in the grinder to ensure that the coffee in the portafilter is providing the correct resistance to flow to cause the pressure drop through the puck to be a little over 9 bar. If you haven't adjusted your grinder, who knows what's going on in the brew chamber. If you haven't adjusted it for a long time, make a big adjustment finer so that you can prove to yourself that the grinder can choke off the flow, then adjust back slightly coarser and slightly coarser in little steps until you're getting good espresso. Remember, unless you're opening a fresh bag, every 12 hours of coffee that was roasted exactly 6 days prior each time, in a climate controlled building where the humidity and temperature can't change, you're not using the same parameters every time.
We're so lucky that grinders are adjustable, take advantage of that feature.

If, on the other hand, the coffee is so fine that it is nearly choking the machine and there's still no crema, then you blame pressure. If blaming pressure, is there excessive flow over the OPV, or is the pump actually stalling?

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Randy G.
Posts: 5340
Joined: 17 years ago

#5: Post by Randy G. »

Ruling out the barista, and if the water has not changed, a very sudden change like that points to the equipment, particularly when using the same batch of coffee. I also think changing the grind to try to force some crema appear is a good start because it is quick and easy. Check how much water is returning to the reservoir during an extraction through the return hose (the shorter one). It could be the OPV needs attention and it is causing low brew pressure. Same with the pump. Another way to find out is to take the machine to another location and use someone else's grinder, and use your grinder on someone else's machine. Examine the burrs of your grinder to make sure that they have not been damaged and for a loose or misaligned burr.
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Pressino
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Joined: 3 years ago

#6: Post by Pressino »

Could be many things, but I'll go out on a limb and say the likely suspect is the grinder. If you have the skills open it up to check the grind chamber and burrs. Could be gunked up with stale grounds or the burrs could be worn out.

The temp in the cup doesn't tell me what the brew temp actually is. I'm going to assume that it is OK.

Marco_305
Posts: 2
Joined: 2 years ago

#7: Post by Marco_305 »

Crema again!

The first thing I've checked was the amount of water flowing back into the reservoir. It was a lot more than expected, so it could be the OPV. It took some time to remove and open it. After many years there was a lot of chalk inside, but no chunks. I cleaned everything and assembled it again. Now the Silvia is working like before. Thanks to Randy for your hint!