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Thread: Nuova Simonelli Oscar Problems

  1. #1
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    Nuova Simonelli Oscar Problems

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all,
    Hoping for some help. I have an Oscar that developed a high temp problem that appeared to be a pressure valve failure. However, the valve was replaced but the machine wont push water through the coffee when the machine is hot unless you use a very coarse grind. It pushes the water through fine when cold....any ideas?
    The local service guy has run out of ideas but he is not a pro service guy just a coffe roaster mainly. No other service people local here in the northern rivers of NSW.
    Cheers,
    Wayne

  2. #2
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    Aug 2007
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    Re: Nuova Simonelli Oscar Problems

    My guess is that it is running too hot and that the machine is getting an air block from the steam in the HX which means the pump can never build up the pressure it should. *Im no expert though so that would be my guess. *Ive found that if I let my water resevoir run dry it will let a small amount of air into the circuit and unless I bleed that out the pump wont get to full pressure.

    Try giving the machine a really long cooling flush before pulling a shot. *See if that makes any difference. *My guess is that you need a new pressure stat(or perhaps just an adjustment). *If that is the case I would be reluctant to run the machine much as it would be running way too hot.

  3. #3
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    Re: Nuova Simonelli Oscar Problems


  4. #4
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    Re: Nuova Simonelli Oscar Problems

    Hi, Thanks for the reply firstly! The U-Tube vision is exactly what it was doing before I took in. He diagnosed a faulty pressure valve and replaced that but it wont pull a shot now. Ill take this info to him and see what he say!
    Cheers,
    Wayne

  5. #5
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    Re: Nuova Simonelli Oscar Problems

    I take it you saw the solution in the comments?

  6. #6
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    Re: Nuova Simonelli Oscar Problems

    Hi Wayne,

    We have repaired several Oscars over time with the same symptom and exactly as it appears on the Youtube clip. This sympton is usually the result of a failing pump, which subsequently starves the heat exchange of a suitable water vulume/flow rate and causing the overheating of the reduced water flow that does pass through it. Problems with the pressure stat tend to manifest themself with the safety valve passing with a big release of pressure. We have had one instance where even when the pump was changed, the symptom persisted and the pressure stat was the cause but generally when we have changed the pump, full water flow is returned to the group. If you are able to rig up a pressure guage and connect it to where the steam nozzle screws onto the steam arm then you can check what the pressure is but my bet is that the pump is at fault. You could also attach a small piece of tubing to the outlet side of the pump and activate the group and then watch the flow rate to see if it is reasonable before looking at replacing deciding to replace the pump as another way of checking..but you would have to know what the normal flow rate is to make the comparison.

    Brad

  7. #7
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    Re: Nuova Simonelli Oscar Problems

    Hi all,

    Thanks for the help! The machine is working again and as per all the great advice it was a new pump thta fixed the machine!

    Thanks,

    Wayne.



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