noetus Senior Member Joined: 13 Feb 2012 Posts: 6 Location: Budapest Expertise: Just starting
Posted Mon Feb 13, 2012, 5:40am Subject: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
I'm a newbie to these forums and pretty much a newbie to all things espresso. Thanks for this great forum!
Got my first machine, a Nuova Simonelli Oscar, about a month ago. Have been using it pretty much everyday.
Yesterday though I get a problem. Machine has been on all day, have already pulled a breakfast and lunch shot. In the evening, try pulling another the shot, and the pump is all quiet and there seems to be almost no pressure. Pump is definitely on, but sounds weak and quiet.
I turn off the boiler and open the steam valve and let all the pressure release. Then I turn on the boiler again, wait until steam is showing at the wand, close the steam valve, and let it heat up. Pull a shot no problem.
This morning, machine is switched off, go through the startup routine, pull a shot no problem.
Machine is left on, a few hours later, try pulling another shot, same problem as yesterday evening.
The machine is under EU warranty, but I'd prefer to fix this myself if it's an easy fix, rather than send the machine away and wait weeks for it to come back (was shipped from a company in Italy and I'm in Hungary).
"You can write down how to make the perfect cup of coffee. But to make it really good, you have to play something fictional, you have to dress up, you have to think, This is the most important thing."
noetus Senior Member Joined: 13 Feb 2012 Posts: 6 Location: Budapest Expertise: Just starting
Posted Tue Feb 14, 2012, 3:23am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
Thanks for the link... had already seen that one, the problem seems slightly similar but also different in my case, where there is a very low sound (the pump is vibrating but it's very quiet) and no pressure, and I can't pull a shot at all. There is no variation within a shot as on that thread. The machine just won't work at all as there is almost zero pressure. To get it to work again I have to release all the steam pressure and reheat the boiler, and that may or may not work.
I have contacted the supplier in Italy and supposedly they are going to get back to me. However I'd hate to have to send the machine in for service, as it will be at least a month without the machine, it would be much better if it's an easy fix to do it myself.
It would appear that the very low sound but still vibrating pump would indicate that there is no outlet for the pressure. However I know what the sound of the pump is like when there is no flow (choking) as I have had that several times due to an over-fine grand and the sound now is quite different, much lower in fact.
Bitches_Brew Senior Member Joined: 4 Feb 2009 Posts: 764 Location: indiana Expertise: I like coffee
Espresso: yes Grinder: yes Vac Pot: no Drip: no Roaster: yes
Posted Tue Feb 14, 2012, 8:35am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
it might be worth asking for a replacement seeing how it's basically new.....maybe even a refund.
"You can write down how to make the perfect cup of coffee. But to make it really good, you have to play something fictional, you have to dress up, you have to think, This is the most important thing."
noetus Senior Member Joined: 13 Feb 2012 Posts: 6 Location: Budapest Expertise: Just starting
Posted Thu Feb 16, 2012, 4:41am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
Well, it means shipping the thing back to Italy, the entire process could take a month or more. I was hoping people on here might have advice about maintenance issues or common problems with this machine.
I have realised that I was wrong to say I got it a month ago - it was a bit longer in fact, I have been using it more or less continuously for about 2 months, on all day and our water area is quite hard.
To be clearer about the system: something gets "stuck", maybe a valve, such that the pump is on and trying to pump but with no flow (hence it goes all quiet). The lack of flow is due to no outlet, not a problem with the pump itself. I can make it "unstuck" in two ways: either by depressurizing the system and letting it heat up again, or, while I am ready to pull a shot, simply switching the entire machine off and on rapidly a couple of times (with the pump switch in the on position) which seems to "clear" the problem and allow the flow through again.
So something inside is "sticking". I don't know how the internals works, but I know there is a three-way valve. Could this be sticking? Could it be caused by calcification? Before taking the warranty issues further, perhaps I should try descaling....
naimnut Senior Member Joined: 13 Jul 2011 Posts: 66 Location: Seattle area Expertise: I live coffee
Espresso: Expobar Brewtus II Grinder: Baratza Vario Drip: Braun Aeromaster
Posted Thu Feb 16, 2012, 1:54pm Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
Seems like I had this problem with my Oscar. Things to check (sorry if these seem too stupid, don't mean to insult your intelligence)
you do have water in it, right? If you've inadvertently used up all the water, symptoms might be as you describe.
You're not using distilled water, right? The Oscar requires water with, at a minimum, trace levels of minerals in order for the system to know that water is in the reservoir. Early when I had my Oscar I filled it with distilled water and it would not work at all. A pinch of salt and all was well.
have you tried turning it off, unplugging it, etc.?
Madurodave Senior Member Joined: 3 Feb 2012 Posts: 141 Location: NH Expertise: I live coffee
Espresso: Rancilio Silvia Grinder: Baratza Virtuoso Preciso Vac Pot: Yama 5 cup Drip: Mr Coffee, perculator Roaster: HotTop B, West Bend Air...
Posted Thu Feb 16, 2012, 8:55pm Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
It almost sounds like some thermal overload is tripping. You said you turn it on, it is fine but after being on it does not. That seems to indicate something is getting too hot and keeps the flow off until it cools back down.
Dave Harley rider, Espresso drinker, Primo XL grill
noetus Senior Member Joined: 13 Feb 2012 Posts: 6 Location: Budapest Expertise: Just starting
Posted Sun Feb 19, 2012, 1:35am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
OK, so I'm gonna try and be as precise as I can with a re-description of the symptoms, what I'm really hoping is that someone with knowledge of how the Oscar works can suggest a few things that might be up with it or just suggest things I can try. (Please assume I know how to operate the machine and that I have been operating the machine successfully for 2 months with exactly the same procedures, water, coffee, etc until this problem suddenly appeared, with no change in my procedures, water, coffee, etc.)
** It actually doesn't matter, as it turns out (I wasn't familiar enough with the problem earlier), how long it has been on for. I can turn it on in the morning, and have the issue, or I can leave it on for 8 hours, and have the issue. It doesn't seem to be 'thermally related', i.e., to how hot the Oscar is.
** The problem is slightly variable, in that the symptoms are not exactly the same each time, but very similar to each other. What happens is that when I switch the pump on to pull a shot, the pump is quiet AS IF it is pumping against a lot of pressure (similar symptom to having choked the pump) and either VERY LITTLE water is pumped OR NO WATER AT ALL. However, it is NOT choked by overtamping too-fine coffee etc. I know this for TWO reasons. First, this can happen even when I don't have the portafilter on. I can simply switch the pump on with NO portafilter on (and hear the pump running) and get NO water or VERY LITTLE water. However, it usually happens when the portafilter IS on. Second, once I get the pump pumping properly (see below) I can then pull the shot successfully without changing the coffee in the portafilter.
** The variation is in the SOUND of the pump and the AMOUNT of water being pumped through. The pump can be VERY quiet, and NO water comes through, or SOMEWHAT QUIETER than it normally is, with SOME water coming through (but not enough pressure to pull the shot), or SOMEWHERE IN BETWEEN. Like I said, the problem is as IF THE PUMP IS CHOKED (pumping against a 'blockage' or too much pressure) and that the 'choking' is variable in quality each time.
** So far, I can usually get the pump to start pumping properly, by doing one or all of the following. (A) I can RELEASE THE STEAM PRESSURE SLIGHTLY but opening the steam wand for a few seconds and then closing it again. (B) I can switch the pump on and off rapidly for a few seconds (not sure if this is very good for the machine though). (C) I can switch the entire machine off and on rapidly for a few seconds, using the main power switch (again, not sure how good this is for the machine). Sometimes just doing ONE of these things gets the pump going; sometimes I have to do more than one or all of the above.
** Once the pump is pumping water through again, I do wonder if the pressure is correct, since the symptoms (described above) are somewhat variable, i.e. , it is not a matter of the pump simply pumping or not at all, but rather a matter of the pump not pumping at all, or pumping a little bit, or pumping a lot. However, once I get the pump pumping again, I do pull the shot ok, but the whole problem is ruining my 'equanimity' with the machine, and I do not have the consistency of shots I had before, but whether this is because even when the pump IS pumping again it is still not always pumping with the 'correct' pressure or it is because I am upset with the machine, I am not sure.
Here are some other thoughts I have had.
** The problem seems to be mechanical, NOT electrical. The diaphragm pump pumps at the correct vibrational frequency whether the pressure is there or not (it just varies in volume according to how much 'pressure' is against it) and all the switches work correctly.
** The problem is consistent with a STICKING VALVE. If there is a valve that is supposed to open to let the pump pump the hot water through, but it is sometimes opening only partly or not at all, I think I would be getting these symptoms. Then, the above three methods (opening steam valve, switching pump/machine rapidly on or off) could be 'unsticking' the valve and temporarily fixing the problem until the next time I need to pull a shot.
** IS THERE SUCH A VALVE? The problem is, I am mechanically minded, but I do not know the internals of the Oscar. Does anyone on this list know? Does anyone on this list think the above symptoms could be caused by a sticking valve? If so, what further tests could I try, and what might be causing the valve to stick?
MikeReilly Senior Member Joined: 28 Oct 2007 Posts: 277 Location: Vancouver Island Expertise: I love coffee
Espresso: La Cimbali Junior D, Gaggia... Grinder: Mazzer Mini Drip: Cuisinart Roaster: Behmor, I-Roast 2, Popper
Posted Sun Feb 19, 2012, 10:25am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
you need a parts diagram. Download it from http://nuovasimonelliusa.com/oscar.html (sorry, they use a javascript to link it so I can't link directly to the file). On the pdf, 2 is the pump, 3 must be the overpressure valve. I would think the problem would be possibly a loose wire to your pump or possibly a failing pump. They are about $50.00 in North America. It could also be something clogged up in your brew path or the OPV letting water back out of the brew path, but then you'd still hear the pump (vibratory pumps are pretty noticeable). If the seller is a good one, they should be able to put you in touch with one of their techs who could walk you through the troubleshooting on it to narrow it down. You did read the thread linked by Bitches_Brew, right? It's got lots of ideas.
noetus Senior Member Joined: 13 Feb 2012 Posts: 6 Location: Budapest Expertise: Just starting
Posted Sun Feb 19, 2012, 10:53am Subject: Re: Nuova Simonelli Oscar - month old machine, pump goes all quiet, no pressure
Thanks, I saw the hydraulic diagram via a link on another forum but it didn't help me a lot (doesn't help that the nomenclature is in Italian).
I DO hear the pump - the pump itself seems to be working, in the sense that I can hear it and the pump vibrates when I switch it on. It doesn't seem to be an electrical problem or a pump problem. It just that it usually it doesn't pump water through and when the water is not pumping through the pump is quieter, consistent with a blockage of some sort.
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