Posted Tue Jun 12, 2012, 3:40pm Subject: Low pressure on Silvia
For a while now I have been experiencing problems with my 10-year-old Rancilio Silvia V1. I have had to increase the dosage to 19 grams to get a double shot of espresso in 25 seconds. I don't have a gauge to test the pressure, but I ran the machine last night with a blank filter and checked the flow from the OPV - it gave me about 140 ml in 1 minute. From what I read this should be nearer 320 ml. Based on this, what should I do next? I assume that there is a problem with the pump, but I wondered if cleaning/descaling might be helpful, before fitting a new pump?
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,683 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Wed Jun 13, 2012, 5:56am Subject: Re: Low pressure on Silvia
A personal opinion is that the flow from the OPV really wont tell you much but I am not an expert by any means.
My standard double shot is 18 to 19g so I really don't see an issue there either, if the shots are running fast, I would think it is more of a grinder issue (you didn't say why you went to 19g, to speed up or slow down the shots)
Rocky is a little dated too and a lot of times your shots need to be in between the steps so to make up for that, you need to add to or subtract from your dose to get the shots where they should be.
More important than the time though, how do the shots taste? If they taste good, as the commercial says, "where's the beef?"
Your post has been up for a little while with no replies so I did want to say welcome to the board!
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coffeeee Senior Member Joined: 30 May 2011 Posts: 52 Location: over the rainbow Expertise: I love coffee
Posted Wed Jun 13, 2012, 7:05am Subject: Re: Low pressure on Silvia
Hello Chris
Yes, it sound like a pump. The rate flow though not accurate is a very good start point if you don’t have a gauge and 320cc/min. is exactly what I found in my machine. A 10 years old Silvia does not have an OPV so you can’t easily adjust pressure and that difference comes from somewhere… I would start with descaling first and then repeat the flow test. If this doesn’t change anything I’m afraid you’ll need to replace the pump. Good luck Avi
Coffee is not a drink...it is an adventure... Author of Rancilio Silvia Mega-Mod and Rocky Timer Mod (see my website)
Posted Wed Jun 13, 2012, 9:34am Subject: Re: Low pressure on Silvia
Thanks for the help and suggestions. Now that I think about it, I had to take the boiler apart to fix a leaking gasket a few months ago and it was absolutely full of scale. I had to scrape it out - descalers were not touching it. I guess I need to disassemble the pump and check that out. To answer calblacksmith - the shots taste good, but have less crema than they used to - the milk is also not frothing as well as before.
JGG Senior Member Joined: 31 Mar 2006 Posts: 1,343 Location: Kentucky, US Expertise: I like coffee
Espresso: PID Silvia; PID Alexia Grinder: Mazzer Mini E (A), SJ; Rocky... Roaster: Hottop D w/PID; Thermometric...
Posted Wed Jun 13, 2012, 10:13am Subject: Re: Low pressure on Silvia
Low flow from the OPV discharge line could be caused by two different things:
A scaled-up OPV that is opening at a too-high pressure
A dying pump
Gushing shots (i.e. shots that are too fast) could be caused by many things, including:
High pressure (i.e. the OPV is opening at a too-high pressure)
Poorly adjusted grinder
Stale coffee
Worn out grinder burrs
A scaled-up OPV is on both lists, so that's probably where I would start. But my guess is that the two are unrelated and that the fast shots are the result of either the grinder or the coffee.
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