New member and straight away asking some help:

My half a year old Nuova Simonelli Oscar has got a new tendency of a pulsing sound. I think this is a resonance, but how to get rid of it? If I release some steam during a brew, it sometimes stops the sound, but not always. I made a short video on Youtube. This vid was with blind filter, a backflush -but the sound is the same on brewing a espresso. The sound has a variety of frequency, and the frequency mostly rises during brewing goes on.

Any ideas on cure -or at least a comment for the harmfulness of the symptom?

Made new video. Seems that as Oscar pulses, the water is coming on left side drain. So it that valve defective?

Strange, possibly a problem with the over pressure valve? (OPV)

OMG! I would tell "bad, bad pump", but if your neplax valve is opening, maybe this is the problem.

The neplax valve is a fixed expansion valve. I think the newer ones are made to open at 16 bar. But maybe the spring inside yours is bad and opening at some point around the maximum output of the pump and even worse - resonating. Very interesting!

I couldn't confirm the maximum pressure of the neplax I've used at my restored Oscar as the 3-way valve was opening around 12-13 bar (I think the 3-way is rated at 10 bar). But as I have installed an adjustable OPV right after the pump to keep things around 9 bar, I didn't care.

You should replace it. Maybe you could add an adjustable OPV and the flow restrictors to the group (best mod I've done to the machine)...

Márcio.

Or could it be that a bad pump is resonating high/low which is opening and closing the OPV?

Yes, maybe... I've read again and Vesa says he got this problem extracting coffee too. Vesa, when you are pulling a shot and the pump makes the noise, do you get water from the valve too?

Márcio.

Carneiro wrote: Vesa, when you are pulling a shot and the pump makes the noise, do you get water from the valve too?

I did a new test. But I did not have to. It's getting much worse. Hardly at all coffee, but plenty of the other show!
Bad video below -there is not that much light in Finland in this time a night.
I'd lean to think the valve is dead.

Asked for the opv from Italy. They informed, after seeing the vids, that it still could be the 3-way solenoid who's to blame. So I opened and cleaned that, but no cure. So new "73012002 VALVOLA NEPLAX VITON 16BAR" is on it's way north. Let's hope that will be the answer.

Hi Oskuk - how did the new valve go? Can you post a picture of it?

I'm a little "late to the party" on this post, but I've started having a similar problem with my Mac Digit. The neplax valve is opening up and staying open, allowing water to pass directly to the drain. I opened up the valve and found that the viton gasket was torn and that the valve piston seemed to be "hung up" along the side and not fully re-seating. This is the original valve, so I ordered a new spring and gasket. They arrived yesterday and I installed them. I pulled a couple shots and everything seemed great. Very quiet, full-volume shots. But the leak started again, filling up a gallon container in about 45 minutes.

Now the questions .... first, should I have just replaced the entire valve? Is the body different in the new valve that opens around 16 bar rather than the 9-ish of the original? The spring that I ordered looks exactly the same, so I doubt it has the higher limit. And, my boiler pressure (according to the gauge) is about 1.2 bar. The group pressure part of my dual gauge is broken, stuck up over 10 bar. Is it common for that gauge to fail? (it is only about a year old). Could there be another issue.

Lastly, is the restrictor you are talking about a good mod for the Mac Digit?

Thanks! Ted