Hi! This is my first post here, often read forum but can't find solution to this.

I've had my Rancilio Silvia for a few years, really pleased with it. Recently I have had no change in my set up (coffee the same, grinder the same etc) and my espresso is suddenly running really fast. I was consistently getting a my desired 30 grams out in about 25-30s. Now coffee is just rushing though - 10/15s for 30g - no matter what I change.

Originally thought it was my grinder playing up (Baratza Encore) but having done a few tests it seems fine, tried going tighter and still same results. Wondered if it was the pressure in the Silvia - again did a few tests to decrease pressure and still getting same results. Ran the test they suggest and it was coming at 9 bars (http://www.pidsilvia.com/Ulka%20Water%2 ... essure.htm) - tried decreasing and still can't get slow flow of espresso.

Not sure where to go next?? Could there be something broken / cracked in group head, gasket etc. I've taken shower screen off and all looks fine and clean. What issue would cause espresso to run so fast?

Please help if you can. Really missing my tasty espresso!!

This sort of problem is often reported. Once the machine is eliminated from contention (since you get 9 bar, we can assume for the moment that this is the case), then the issue is usually grinder or stale coffee. The grinder should be able to grind all but the stalest coffee, fine enough to choke the machine (no coffee comes out, or very little). Rather than move the grinder control a little at a time, set your grinder as fine as it will go and see what happens. If your machine still will not choke, then it may simply need a calibration (see your manual). If after recalibrating the grinder, you still get gushers, then try another coffee, preferably from a different supplier, and one who indicates the roast date. Finally, if your grinder is old or has been abused, it may need a new burrs set, but this is rarely the case when getting gushers.

Assuming the grinder is okay - which you can check by feeling the grounds:

I would test the over-pressure-valve (OPV) and the plumbing surrounding it, as what you are experiencing is typical of older SBDU (single-boiler dual-use) machines.

If you run the pump with the brew valve and steam valve closed, what happens?

Do you get good flow through the shorter hose back to reservoir or does the pump stall?
If you get good flow back to reservoir, then the OPV is working. If you have a way of testing pressure you might want to adjust the OPV down somewhere around 8.5 or 9 bar.

But, as others have said, it's almost certainly an issue with the coffee in the portafilter basket. Once you're sure the OPV is working, dial in the grinder to the point where it chokes off the brew flow, then back it off slightly coarser to adjust your prep for that 30g in 30 sec you've been enjoying.

I have a Baratza Sette and very occasionally, a bean will get stuck somewhere in the mechanism, such that it affects the grinder's ability to space the burrs correctly. Taking it apart, cleaning everything out and make sure there are no stuck beans anywhere always fixes the problem for me. I know the Encore is a different grinder, but I imagine Baratza has a certain mechanical process that has some similarity. Worth a look anyway, since it doesn't cost anything to just clean it out.

Thanks so much for all these replies, really helpful and much appreciated!

I agree that I think (hope) the issue must now be with the grinder, I've gone as fine as i can and the coffee still gushes through. On the tightest setting on the grinder the coffee beans actually seem to struggle to go through the grinder, it feels like it takes a lot longer to grind 17g of beans than it did before. To me the coffee feels very fine but it is a bit inconsistent, with some larger grounds. I've never properly inspected the coffee when it was working properly so I can't compare directly.

OPV valve on the Silvia seems to be working fine, and test indicated 9 bars of pressure.

Next step is to take the grinder apart and give it a good clean!