I have a Rancilio Silvia. It is about four years old, and has been fine for making the Americanos my wife and I drink daily - until recently, when I noticed an increase in the time it was taking to extract the usual amount of coffee. I loosened up the grind a bit, but several days later it was taking more time again. I suspected low pressure, perhaps a pump going bad. I called 1st Line for advice and it was suggested that I de-scale the machine, so I did, but there was no change in its behavior. I also notice a bit of lag before water comes out of the wand, and occasionally a slight percolating sound coming from the machine. Can anyone suggest a course of investigation?
Put a blind filter into the group and turn on the brew switch while watching the return tube in the reservior. If no water comes out suspect the pump.
I removed my pump and powered it with the inlet hose in some cheap vinegar. I directed the outlet hose back into the jar of vinegar. After running the pump for about a couple of minutes I let it sit with the vinegar in it. After the hour I ran the pump again. You may have to prime the pump by sucking on the outlet hose while the inlet is under the vinegar.
After that all was well with my machine. I did not have to dissasemble the pump. While in the midst of this I posted a question about the pump losing pressure and got some replies with links to drawings of the pump to use if I had to take it apart. I'll look for the string.
Feral_Boy Senior Member Joined: 12 Dec 2007 Posts: 21 Location: Snowmass Village, CO, USA Expertise: Just starting
Espresso: Silvia Grinder: Macap 4 doserless
Posted Sun Oct 31, 2010, 10:16am Subject: Re: Rancilio Silvia - low pressure?
Today I found the time to tear the machine apart. Here's what I found:
1) With a blind filter in place, water does return to the reservoir, though more slowly and with more delay than I suspect is correct. (Though I have no basis for this suspicion!) 2) I took the check valve (inside the vibe pump) apart and found no scaling at all. 2) With the case dis-assembled, I noticed a hissing. I'm not 100% sure, but I think it's coming from the OPV return. There is no sign of leaking (staining, mineral buildup) anywhere. The percolating I've heard is the sound of steam returning to the water reservoir from this OPV.
Is this (i.e., the noisy return) normal and I'm only noticing it because of the slowed/delayed pours?
My next step is to fabricate a pressure gauge for the PF to check my brewing pressure to see if the pump is faded, but I live in the middle of nowhere (Roaring Fork Valley, CO) and don't know of a convenient source for parts.
Any thoughts, or recommendations for a parts source?
You have a constant leak over your relief valve. Disassemble it and look at the rubber or teflon faced seal. If just cleaning them and descaling the body of the valve then reassembling it seems to allow it to seat properly (And prevent you from blowing through the valve), then it is probably good to go for a while longer. If not, replace it. This comes up as Rancilio expansion valve Not sure if that's right for your Silvia, I would assume your machine has the expansion valve teed right at the pump. Dunno. But it's easy enough, stop the leak, adjust it to only leak once 9.5 Bar pressure overcomes the spring, right?
Sorry for the tardiness of my response, bcarrigg90. This was a couple of years ago, so I'm depending upon my fuzzy memory. I cobbled together a pressure sensor from my original portafilter (which I was no longer using) and some hardware store parts - an air compressor gauge, brass "T", reducers, and a petcock. I believe the PF has a standard 3/8" pipe thread and so the "T" was bought to match that. The gauge and petcock were 1/4" pipe thread, and the reducers are there to fit them to the 3/8" "T". (The petcock, with some adjusting, allows for a standard pour while checking the pressure.) All together, it cost maybe $15. I determined that my brewing pressure was too low (and I don't know offhand what that pressure is supposed to be), and tried unsuccessfully to raise it. I then took apart the OPV. Nothing was visibly wrong with it as far as I could tell - the spring may have been fatigued - so I replaced the OPV with a new one. That solved the problem. I then used my cobbled gauge to adjust the new OPV setting.
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