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Nuova Simonelli Oscar -- a novice's troubleshoot
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Discussions > Espresso > Machines > Nuova Simonelli...  
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ehrivnak
Senior Member


Joined: 3 Jan 2014
Posts: 2
Location: Toronto
Expertise: I like coffee

Posted Fri Jan 3, 2014, 12:13pm
Subject: Nuova Simonelli Oscar -- a novice's troubleshoot
 

Hello,

I've been proudly owning and operating a Nuova Simonelli Oscar at home since September of this year. The machine came highly recommended by a coffee geek friend of mine. The machine was purchased used, but came with a receipt of a complete tear down and de-scale prior to purchase. The company who did the de-scale is reputable, as was the receipt, and the sellers struck me as honest and trustworthy. I have all confidence that a de-scale did take place, and that the machine was not used until my purchase of it. I also acquired a Pasquini K2 burr grinder. From September to December of this year, my wife and I pulled about 2-3 shots per day with no complaints whatsoever--great crema, great pressure, great taste.

Lately however I've noticed the quality of the coffee is deteriorating. Sadly I am a bit of a coffee noobie and so I hope I'm not eaten alive on these forums. My glossary of espresso terminology is growing as is my understanding of the machine, and I will try my best to describe what I've tried and what the problem seems to be.

In short, the pressure of the water emerging from the group head has diminished significantly. When we first started using the machine, water would come shooting out when running the machine. Now the water slowly emerges as more of a trickle. The machine doesn't seem to have the pressure to push water through finer grinds, and so the taste and the crema produced on the shots is far worse. Shots are taking waaay longer to pull as well, likely a consequence of the diminished pressure. In addition, my perception is that this change in pressure occurred fairly rapidly. It almost seems as though one day it was working great, the next, very poorly. The manual states that opening the steam knob and rapidly pressing the run button can help the pump run water through the machine and increase pressure. I've used this method a couple times in the past with good results, but the technique doesn't seem to be working now.

I feel as though I've been taking fairly good care of the machine. I purge the group head before and after every shot, and cleaned the dispersion screen with a stiff bristle brush daily. I have also tried carefully backwashing the machine after watching a few YouTube videos. Some backwashes have been done with a detergent and some with simply water. No improvement.

I've considered trying a descaling agent but I'm skeptical for two reasons: one is that given what I've read about the machine and it's maintenance on a few websites, it doesn't sound like the machine should need a de-scale so early on. We live in a metropolitan city and the water hardness is slightly high (8-9 grains/Imp gallon) but still significantly lower than the place we purchased the machine from. The other reservation I have is an acquaintance of mine who is adamantly opposed to a de-scaling agent on the Oscar: he's maintained in several conversations that the only way to de-scale this machine (for whatever reason) is to take it apart and give it an acid bath. I am a hospitality professional and this acquaintance has supplied my restaurant with its espresso machine and grinders, and regularly services our machines at work. So his opinion does give me a little pause.

So that's it! I'm fairly handy and am not scared to open up the machine and have a look around, but without a little guidance I wouldn't know what to look for or how to affect positive changes. If there's anyone out there who has the time or the inclination to lend a few pointers, I'd really appreciate it!

Cheers!

Eric
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fnacer
Senior Member


Joined: 25 Feb 2007
Posts: 463
Location: Denver
Expertise: I love coffee

Espresso: Salvatore E61, Vivaldi Mini...
Grinder: Mazzer Mini, Gaggia MDF,...
Roaster: Behmor 1600
Posted Fri Jan 3, 2014, 11:09pm
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

ehrivnak Said:

he's maintained in several conversations that the only way to de-scale this machine (for whatever reason) is to take it apart and give it an acid bath

Posted January 3, 2014 link

A Simonelli technician I spoke with when I bought my used Oscar had a seemingly similar opinion. But his reasoning was that if you were going to hire him to descale the machine, your money would be better spent having him do a complete tear down so he could replace the many flimsy (my description, not his) plastic components between the water reservoir and your cup.

While I agree that scale should not be the cause, you really should consider eliminating it as the culprit. But perhaps you'll feel more comfortable doing that once you hear from others on the issue.

In the meantime, perhaps you could clarify a few things that may help point to a mechanical failure:

- Is the water flow visibly reduced when you draw water from the group head without a portafilter in place?
- Does the pump sound the way it always has when it draws water into the boiler?
- Do you see any water going to the drip tray, back into the tank (if you have an OPV), or dripping under machine?
- Does the machine deliver noticeably less steam and more water through the steam wand after you pull a few shots compared to before you pull any shots?
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plindy
Senior Member
plindy
Joined: 27 Nov 2002
Posts: 66
Location: Seattle
Expertise: Just starting

Espresso: NS Oscar
Grinder: SJ Pharos Lido HG-One
Posted Sat Jan 4, 2014, 6:16am
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

Before we proclaim the pump is failing , try a short test. Remove the shower screen and breaker plate  from the group head , run the pump for 30 seconds into a measuring bowl.
500 ml ?
Older Oscar's water tanks temperature 120 F / 49 C while the Ulka pumps are rated for  77 F / 25 C . So it's not unheard of for pumps to fail.
Confirm that you have a ground coffee breaker plate and screen , large diameter screen that fits over the breaker plate. As opposed to a pod coffee kit , a small diameter screen that fit into the center of a thick [11 mm] breaker plate.
reference

Sorry for your troubles  
Welcome to CG
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Coffeenoobie
Senior Member
Coffeenoobie
Joined: 11 Dec 2011
Posts: 2,973
Location: PNW
Expertise: I like coffee

Espresso: N S Oscar
Grinder: K30 & Vario W
Posted Sat Jan 4, 2014, 10:31am
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

My first thought is pump.  Try Plindy's test.  Any machine over 4 years old I would probably have a pump on hand to replace in a pinch.  Mine was two when I got it and the pump was working but weak.  As soon as I replace it, it was better.   The membranes get stiff and they no longer sell the membrane replacement kit.

If you see pulsing and steaming water then you have a bad safety valve, also a common problem.  I have replaced that also.  6$ part.  I would not descale it unless the fill probe looked cruddy, the tech probably did it already.

I think this summer I will do an Oscar descale that doesn't tear down the whole machine and film it for everyone see a descale without tear down using the boiler drain instead of the steam wand.  I don't like the idea of the steam wand descale.

 
Coffeenoobie

Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder.

My coffee treasure map...
Click Here (maps.google.com)

Oscar trick out: http://s156.photobucket.com/user/GandBteam/story/14231
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ehrivnak
Senior Member


Joined: 3 Jan 2014
Posts: 2
Location: Toronto
Expertise: I like coffee

Posted Sat Jan 4, 2014, 3:00pm
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

Hi everyone and thank you so much for the feedback. Let me try to answer everyones questions:

Fnacer:

- The water flow was/is visibly reduced when drawing from the group head without a portafilter.
- The pump sounds the same as always.
- I have been seeing a little water dripping down into the drip tray and there is occasional water under the machine. I should mention, however, that I'm not the most accurate when it comes to refilling the reservoir.
- Steam remains fairly similar before pulling shots and after, though typically when the machine is first turned on, the first element out of the steam wand is water, not steam. It can shoot water for up to 1-2 seconds before switching over to steam. After that, not an issue.

Plindy:

After removing the shower screen from the group head and running for 30 seconds, I only got between 50-100ml of water. Much lower than your suggested 500ml. I wasn't sure how to remove the breaker plate: it is the large copper plate surrounded by the black gasket if I'm not mistaken? And finally, the diameter screen fits over the plate, not in the centre of it (your former description).

Coffeenoobie:

If you made a video I would watch it for sure! I'm not sure what you mean by fill probe unfortunately; if you could explain that term a little further it could be a great way for me to monitor scale buildup in the future.


So, the problem was bothering me for some time yesterday and this morning so I thought I'd open the machine and poke around. First I did a thorough clean of the group head by removing the shower screen and soaking it in vinegar water. lots of scrubbing and wiping. It was really fun to open the machine for the first time! I first considered messing around with the ma-ter pressurestat but then decided I was a little out of my element. Finally, I followed Plindy's reference link (thanks so much for that!!) and found a troubleshoot titled "it goes out little water of the group coffee." It's a poor translation but it seemed to describe my problem.

Anyway, I followed the instructions, removed the solenoid valve and took apart the cylinder. Full of scale! Further, when I ran the machine without the valve and cylinder attached, much of the outgoing water contained scale as well. Since I had the machine open I thought I'd run a whole reservoir through it with a little vinegar dilution to flush out as much of the scale as I could, followed by a reservoir of clean water. Once all that was done I put everything back together and the pressure had improved substantially.

So the battle is won but the war is far from over. Is it normal for an Oscar to scale up that badly in a 3-4 month period? We're talking a couple tablespoons or more. How often do you guys descale your machines? Are there any preventative measures that can be taken to diminish the need for this process? And what is the best way to measure water tank temperature Plindy?

Guys, thank you so much for your help and suggestions. This is a great forum!

Cheers!

Eric
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Coffeenoobie
Senior Member
Coffeenoobie
Joined: 11 Dec 2011
Posts: 2,973
Location: PNW
Expertise: I like coffee

Espresso: N S Oscar
Grinder: K30 & Vario W
Posted Sat Jan 4, 2014, 4:57pm
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

Unless your water is insanely hard it should not take 3 months to scale up. Once a year or so would be more normal. The tech could have done a bad job of you water is not that hard.  Your shower head can tell you how hard your water is. The probe is the one in the middle of the boiler. It lets you see a sample of the inside of the boiler without taking it apart.

 
Coffeenoobie

Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder.

My coffee treasure map...
Click Here (maps.google.com)

Oscar trick out: http://s156.photobucket.com/user/GandBteam/story/14231
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plindy
Senior Member
plindy
Joined: 27 Nov 2002
Posts: 66
Location: Seattle
Expertise: Just starting

Espresso: NS Oscar
Grinder: SJ Pharos Lido HG-One
Posted Sun Jan 5, 2014, 5:46am
Subject: Re: Nuova Simonelli Oscar -- a novice's troubleshoot
 

The breaker plate needs to come off , and be cleaned.
Early breaker plates , 8 holes circular pattern , larger than 2mm dia holes
Later breaker plates , 8 holes square  pattern , smaller than 2mm dia holes
Tap off with non marring tool , wood or plastic end of screwdriver.
Should pop right off , be ready to catch
No portafilter , breaker plate , no screen
500 ml in 30 seconds ?

Water reservoir temp , kitchen thermometer , in reservoir fill hole , gives ballpark value

Descale for Oscar , note difference between boiler and HX , each needs it's own method.
And each can be done without the other being cleaned. Check the bottom of Elektro's page.
Major concern for boiler descale , the brain box lives near to the bottom of the machine...
Not as much of a concern for a HX descale , however be aware...
HX should be a greater concern for you at this time.

And then finally the 5 mm brew path from port 1 of the three way to the 3mm path to the breaker plate , and shower screen.  tobacco pipe cleaners  might help

Ensure the 3 way o-ring are serviceable ,  and tight  to the group head , the upper screw can be troublesome.

G'luck
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