I use Silvia and Rocky doser grinder.
I had no issues until lately. Shots started to become shorter regardless of coffee type. i.e. 10 seconds length. If I fill the basket to the max it still has fast flow with the same amount of time.

I've tried to dial the grinder and got to the finest. As it did not get any better I thought the burrs needed changing. Unfortunately, the outcome is the same after replacing.
The screen is sparkling clean and so are the rest of the parts.

The water output w/o the PF is 310 ml for 30 sec. I read somewhere it needs to be 200-280 ml. For me it sounds sensible that high pressure may lead to water pass through the puke too quickly. Consequently, I have temporarily adjusted the OPV because I just saw somewhere that this could be another reason...but alas it did not change anything
It is noteworthy that the only I haven't checked is the pressure. I've recently bought a bar gauge online and still waiting for it to come through the post.

My tamping and amount of coffee remained the same. I also make sure to run water through the group head to lose any extra steam before installing the PF in place.

I am clueless of what might be the problem!!! (Frustrated... )
I don't remember clearly what I did that started it. I can only think of two things, which might be completely unrelated but I write them to give you a full background:
1. I once caught for a fraction that there was no water and added it. Whether it started straight after it, I can't tell you.
2. I gave the machine a full clean including, boiler, back flash and screen.


Thank you very much in advance for your patience reading and hopefully assistance in my matter,
Roy Esh

I'm not that familiar with that grinder, so I don't know if it should be able to choke the Silvia, but if the fineness looks similar to what you were using prior to the problem, that would be an indication that it's something else.

Since you haven't tested the pressure, it seems possible to me that if the OPV has failed the pressure might be too high. I think the pump delivers about 15 bar, so if the OPV failed you may well be seeing upwards of 13 bar.

How freshly roasted is your coffee?

Are you certain that you have adjusted the grinder to the "finest," whatever that is? You should be able to choke the Silvia with a Rocky.

OPVs can get stuck... you regulated it but you said you have no pressure gauge yet... did you take it apart and cleaned?
Have you tried chocking the machine and see what is the flow back in the tank from the OPV?

Coffee freshness will have a huge impact. For myself beyond 2 weeks past roast date and not usable for espresso. It will just pour through. If I put freshly coffee on say 1-2 days past roast and forget to adjust the grind to coarser after using old coffee often nothing will come out.

What is the roast date of your coffee?

Also what weight of coffee are you using?

I dunno, in my experience, stale coffee does make a difference, but not THAT much of a difference. When people are having problems this extreme, not able to get the shot time longer than 10 seconds, the problem is not the coffee. If you can't grind stale coffee fine enough to get the shot time up to 20+ seconds either the grinder is not going fine enough, or the pressure is too high.

Roy,

Welcome to HB. Can you describe this step in a bit more detail?

roy750 wrote:I've tried to dial the grinder and got to the finest. As it did not get any better I thought the burrs needed changing. Unfortunately, the outcome is the same after replacing.

Do you hear the chirp of the burrs as the grinder approaches the zero point? It has been a while since I've been inside a Rocky grinder, but there is a stop screw that keeps the hopper from being rotated beyond the predetermined range. If you screwed the hopper back onto the upper burr carrier before the burrs were in the correct range for espresso, this screw will prevent you from grinding fine enough for espresso.
Image: Rancilio Rocky Parts Breakdown, originally posted here

See quote below from original post for image context:

genovese wrote:Interference from the stop screw that sticks out from the bottom of the hopper? You may have reattached the hopper to the upper burr carrier in a different orientation (there are 3 choices) than it began with. The screw is there for good reason, but if it's in the wrong location, it will interrupt adjustment in the useful range of the threads, which is within the first 180 degrees or so of burr-zero. It's the unlabelled screw at the center of this diagram:

image

So take the hopper back off, rotate 120 degrees and try again.

Cheers!

- Jake

Grinder, grinder, grinder, OPV and coffee In that order. Unless the coffee is total crap, you should still be able to choke the machine with a Rocky. As Antonio says to check the OPV; put a blind basket on the machine (or put a piece of rubber in the bottom of your regular basket) and look for water flow back to the reservoir. If water is returning, then the OPV is not stuck closed. But, really, 90% chance it's the grinder.

I would think this too except that the OP "had no problems until recently" Unless something changed with the grinder, I'm not sure how regular burr wear could have changed things so drastically, but a stuck OPV might. Now if they said it happened AFTER they changed the burrs, then I would suspect the limit screw was set in the wrong place. Of course they may have also failed to disclose a change that happened with the grinder preceding the problem, but assuming no changes with the grinder I'm betting on OPV.

To check the operation of the OPV, use the blind basket, hold the return hose over the reservoir, and turn on the brew cycle. When the pump begins to labor, water should be flowing out of the hose. Adjusting the OPV should cause the volume of water from the hose to vary.