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Oscar Pump Problems (again)
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Discussions > Espresso > Machines > Oscar Pump...  
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Markarian
Senior Member
Markarian
Joined: 27 Jun 2012
Posts: 658
Location: Seattle Area
Expertise: I love coffee

Espresso: ECM Technika IV Profi WT-WC
Grinder: Baratza Forte AP, HG One
Vac Pot: Bunn Trifecta MB
Drip: Moka, Aeropress, Hario V60
Roaster: Behmor 1600
Posted Sun Dec 9, 2012, 8:49pm
Subject: Oscar Pump Problems (again)
 

Hey everyone,

I would love to resolve this once and for all. About a month ago, I was noticing major pump inconsistency on my Oscar and I thought it was how the machine was supposed to behave. Then I stumbled upon an older thread from Noobie who said she had the same problem and provided a video. I immediately drove down to Simonelli and picked up a new pump. Every morning since then, I've had the pure glory of an elegant, oozing crema cone pouring my double in exactly 30 seconds with enough tiger striping to open a wildlife preserve...

Until today.

I was finishing up the last of my fresh roast batch when all of a sudden, about 2/3 of the way through the pour, I heard one of the relays click and the pump suddenly sucked backward and made this weird pulsing noise. I immediately turned it off and hit the web, looking for answers. My friend suggested the Ulka pump may have burnt out its diode, so we bought a new one at the hardware store and installed it. At first, it seemed to make the pump more consistent, but I quickly saw that no matter what my grind, tamp, roast...All my shots pour turbulently, gushing out with lots of little spurts and sprays out the bottom of the PF. Before I replaced this pump, I would hear the relay click before the pump suddenly got all crazy. I've varied my cooling flush, blackflushed twice, and I only use filtered water. The machine was thoroughly descaled less than three months ago.

I'm really lost here, and I don't know what to do at this point. I don't want to give up on Oscar, but I'm out of ideas. Thanks, as always.
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Coffeenoobie
Senior Member
Coffeenoobie
Joined: 11 Dec 2011
Posts: 3,052
Location: PNW
Expertise: I like coffee

Espresso: N S Oscar
Grinder: K30 & Vario W
Posted Sun Dec 9, 2012, 11:02pm
Subject: Re: Oscar Pump Problems (again)
 

The relay sound is troublesome, I have not had an electrical issue with Oscar just mechanical ones.  You need a meter and open the case up and look fried relays/cables.  Leaks near the brain box....

 
Coffeenoobie

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

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Oscar trick out: http://s156.photobucket.com/user/GandBteam/story/14231
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Markarian
Senior Member
Markarian
Joined: 27 Jun 2012
Posts: 658
Location: Seattle Area
Expertise: I love coffee

Espresso: ECM Technika IV Profi WT-WC
Grinder: Baratza Forte AP, HG One
Vac Pot: Bunn Trifecta MB
Drip: Moka, Aeropress, Hario V60
Roaster: Behmor 1600
Posted Mon Dec 10, 2012, 2:08am
Subject: Re: Oscar Pump Problems (again)
 

What would the brain have to do with the brew pressure? Why would a relay clicking suddenly cause a surge in pressure. Could it be the fill valve? I'm really confused at this point.
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 581
Location: Los Angeles
Expertise: Professional

Posted Mon Dec 10, 2012, 2:20am
Subject: Re: Oscar Pump Problems (again)
 

Markarian Said:

no matter what my grind, tamp, roast...All my shots pour turbulently, gushing out with lots of little spurts and sprays out the bottom of the PF. Before I replaced this pump, I would hear the relay click before the pump suddenly got all crazy.

Posted December 9, 2012 link

curious about this.   im sure the shots wouldnt gush and be turbulent if your grind was fine enough to choke the machine.  try going back to step one perhaps?  find the choking point and adjust the grind from there?  

Also, im curious about your dose prep/distribution.  Previously i had thought i had some strange pump issues(severe channeling like you're having) and since i've somewhat changed my mind and i think it was because of a badly distributed basket of coffee.  Since then i'd played around with NESW(it's more like n to s, e to w, ne to sw, nw to se and on and on) and that helped.  Currently i'm using tek's idea of dumping the grinds into a milk pitcher and shaking it up and then evenly pour it into my basket, finger level it and then tamp straight.   It's been working very well for me.
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Markarian
Senior Member
Markarian
Joined: 27 Jun 2012
Posts: 658
Location: Seattle Area
Expertise: I love coffee

Espresso: ECM Technika IV Profi WT-WC
Grinder: Baratza Forte AP, HG One
Vac Pot: Bunn Trifecta MB
Drip: Moka, Aeropress, Hario V60
Roaster: Behmor 1600
Posted Mon Dec 10, 2012, 3:26am
Subject: Re: Oscar Pump Problems (again)
 

New developments and it's not good:

I went to pump a bit after leaving the machine for a couple hours and it looked more even so I decided to pull a shot. It was smoother, but the brew temp was very low and the shot was poorly extracted. I decided to crack the steam knob and see what I got out. Water. Because the machine doesn't have a vacuum breaker, I know I need to bleed the false pressure when it comes on, which I did hours ago after adding the diode to the pump (no change, BTW). The boiler had almost completely depressurized, even after it had been properly vented hours before. It had never done that before. I let it boil for a couple minutes then cracked the steam wand again. Lots of water came shooting out, indicating the boiler was overfull.

After the pStat kicked off the boiler cycle, I decided to run the pump again. Now the flow was once again uneven, turbulent and sometimes even completely stalled before resuming again. So we have the following symptoms:

-Running perfectly until this morning
-Suddenly gushes and sucks back during a perfect shot (accompanied by a click), and won't pull right again afterward
-Brew temperature is way high
-Brew pressure is inconsistent and suddenly way too strong
-Boiler loses pressure after sitting for a couple hours
-Steam wand shoots out lots of water after idle (an ounce or two at least)
-Shots don't infuse for 6-8 seconds like they did before, instead surging right through and leaving a soggy puck

Could this be a hole in the HX itself?? I'm also thinking it might be the brain suddenly going stupid, but why would the pump pressure ever change? I should mention the pump is brand new and the machine was having similar problems for a while before I replaced the pump.

Frank, my grinding and distribution are not at issue here. This failure literally happened right before my eyes on a perfect shot, after two more perfect shots, with three day old beans. I have my grinder dialed in to specific settings I know work with each type of roast and if anything my tamping technique is a bit on the strong side. I went many notches back and tried to choke the machine. The pour was slower, but there was still a lot of little sprays and there was a lot of turbulence against the basket with no smooth pour or drip. You could tell there was a hell of a lot of pressure, more than was necessary.
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 581
Location: Los Angeles
Expertise: Professional

Posted Mon Dec 10, 2012, 5:23am
Subject: Re: Oscar Pump Problems (again)
 

as far as i know, the only thing that actually "clicks" is the pstat.  It's also what controls the temp and pressure which could explain the issues with your brew and steam wand pressure and temps.

the 6-8 seconds things...that's weird.  those 6-8 seconds i thought were the basket filling with water and then building full pressure.  If it's instant water...i would think it would be a too coarse grind issue.  

also, im thinking if the pressure is THAT high, the pressure relief valve on the left of the brewhead should release some of that.
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 581
Location: Los Angeles
Expertise: Professional

Posted Mon Dec 10, 2012, 5:33am
Subject: Re: Oscar Pump Problems (again)
 

frank828 Said:

also, im thinking if the pressure is THAT high, the pressure relief valve on the left of the brewhead should release some of that.

Posted December 10, 2012 link

btw, the times that i've choked my machine and also when i backflush my machine, the excess pressure does get released through that valve.

i know the baratza machines are known not to be the most durable as far as being able to hold their grind settings...i know you dont think that's likely the case...it's just something that keeps coming to mind because of all the issues ive read regarding baratza.
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Coffeenoobie
Senior Member
Coffeenoobie
Joined: 11 Dec 2011
Posts: 3,052
Location: PNW
Expertise: I like coffee

Espresso: N S Oscar
Grinder: K30 & Vario W
Posted Mon Dec 10, 2012, 10:02am
Subject: Re: Oscar Pump Problems (again)
 

There could be a hole in the HX.  The water in the steam wand is troublesome. I am concerned about the relay click that you said came right before the trouble starting.  That is why I thought electrical something shorting out.  But a sudden loss of pressure could be a leak in the boiler of the HX tube that could over fill the boiler possibly it draining into the boiler is causing the back flow.  The click I guess could be the water sensor in the boiler shutting down as it over fills from the shot.

I would call NS today and ask the tech what it means when you have your systems.  They should be able to tell you right away.  Then order the parts you need.

 
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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Coffeenoobie
Senior Member
Coffeenoobie
Joined: 11 Dec 2011
Posts: 3,052
Location: PNW
Expertise: I like coffee

Espresso: N S Oscar
Grinder: K30 & Vario W
Posted Mon Dec 10, 2012, 10:03am
Subject: Re: Oscar Pump Problems (again)
 

be sure to take lots of photos and post so we will all know next time.

 
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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mthedude
Senior Member


Joined: 28 Jan 2008
Posts: 314
Location: IA
Expertise: I live coffee

Espresso: Nuova Simonelli Oscar
Grinder: La Spaziale Junior
Vac Pot: n/a
Drip: Cuisinart Grind & Brew
Roaster: n/a
Posted Mon Dec 10, 2012, 12:39pm
Subject: Re: Oscar Pump Problems (again)
 

If you're not getting ANYTHING from the red hose on the left side of the group out of the expansion valve, I'd say you at least need to take it off and soak it in solution to see if that's your problem. I've had to do that once. There's a spring and a little plastic ball in there that is supposed to open at a certain PSI, I wonder if your expansion valve is stuck shut and causing your 3 way to open in the middle of your brew?

It's very easy to remove with an adjustable wrench from the top of the machine, especially if you take the front cover off.
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