Rancilio Silvia Brew Pressure Trouble

[dim]

My Silvia used to produce very decent shots, but its recent the quality is really, really bad. There seems to be a problem with pressure, I don't know how to resolve it and need a few suggestions.

The machine seems to choke, even without any resistance. A have unmounted the water spreader, and let some water down (without porta-filter), is was rather dripping then flowing. I played around with the pressure valve but no success at all. I also tried to descale the machine (I used vinegar-water 1:1 mix), the pressure was MUCH better when the vinegar-solution was running through, but it fell back to 'dripping' as soon as I used pure water again.

I made a test, you can try it with your Silvias to compare:
I put everything to its previous state (mounted the water spreader and put the pressure valve to its original position). Then, I plugged-in the empty porta-filter (no basket) and let water down for 28 seconds, catching it under the porta-filter as well as the water coming from the overflow hose.

I ended up having exactly 2oz in the front-cup AND 2oz from the overflow hose (4oz in total). I can't believe that this is normal, why should the machine pump any water through the overflow-valve if there is no resistance at the front? Something must be blocking the water-supply, do you have any idea what it could be?

I really appreciate every advice, thanks in advance,
Dim

[jggall01]

...The machine seems to choke, even without any resistance....I ended up having exactly 2oz in the front-cup AND 2oz from the overflow hose (4oz in total)....

Sounds like the 3-way valve is not opening completely when in the brew position.

Jim

[mhoy]

How old is the machine?
Do you use soft water?
Have you ever descaled the machine?

Mark

[Randy G.]

I agree with the two previous posts, in general order of most likely:

1 - a clogged or mis-functioning 3-way valve. Disassemble and clean as per these instructions:
http://www.drjtech.com/silvia/
You can test that - does water flow at a good rate through the hot water wand when the hot water function is used/ If yes, then either this or #2 is probably the reason it is not working correctly.

2 - if it is clean, it could be the coil has failed. Using an ohm meter, you should be able to read low resistance in one direction and near infinite in the other.

3 - depending on age, there is a small possibility that hard water deposits have built up and caused clogging somewhere.

4 - it could be that the hose from the reservoir to the pump is either kinked or clogged.

5 - if the test in #1 for the water flow through the hot water wand shows low flow, it could be a failing or clogged/dirty pump.

6 - when testing the flow rate for brewing, does a lot of water (or any water) come through the bypass hose? if it is a lot of water do the same check with the hot water wand function. if the hot water flow is low but the bypass hose is flowing a lot of water, it could be a mis-functioning overpressure relief valve.

That should keep you busy for a while!

[dim]

Hi Randy,

thank you so much for your reply (to others as well). The water flow from the hot-water wand is perfect, there's more than enough pressure on it. Therefore it seems like #1 or #2. I will try to clean the 3-way valve today.

In #2 you mentioned the failing coil, where exactly do I need to measure the resistance (just in case, #1 will keep me busy for today ).

@Mark: I tried to descale the machine already a few times (this was my first suspicion), but it only got marginally better. Unfortunately I'm using hard water (London, UK) but I run it through a Britta filter.

[Randy G.]

I don't remember the wiring on the coil, but if you use an ohm meter on the power connections on it (I don't remember if it is two or three wire) you should get current flow in one direction and not in the other. With the cover plate off, the 3-way should "click" when the brew switch is turned on and off. If it doesn't, check that voltage is being supplied. If after cleaning the 3-way it still doesn't work and the coil is getting voltage, then the coil is bad. It has a diode in it and these can fail.