Posted Mon May 20, 2013, 12:13am Subject: Old NS Oscar descaling
I just purchased an old Oscar that seems functional. "Looks" clean on the outside and inside, but obviously not cared for properly. Not sure what year it's from, because as usual there is no date recorded on the serial number plate. I can see that the date on the CEME pstat is 2003/05, so it's likely from after that.
Owner couldn't get it to put out espresso he liked. It always has an alarm on the water level until it heats up. He was just never happy with it after a year or messing around, so I got it + 6 Illy IPA cappuccino cups & saucer + 6 Illy IPA espresso cups & saucer for $265.
It was heated up when I purchased, showed good steam at the wand and hot water out the brewhead. At that price I was happy. Removing the top at home it looks pretty clean. No signs of rust yet either, although I have seen some dripping under the machine. The portafilter is well worn - so it's had some use I think.
I don't have a blind filter, so I corked up the portafilter and ran a few backflushes - nothing surged on the back flush for the first few cycles. Eventually I'm getting some backflush through. It was completely plugged I guess. So I'll have to clean, and possibly dismantle the entire group to see how bad that is.
Mixed up a little citric acid solution and put it into the reservoir to flush the HX brewhead. That started coming out like a beautiful sapphire blue! Not what I wanted to see, but it's inline with the rest of the neglect. I've been descaling the HX side for a while, and blue is getting thinner. So hopefully the end is near.
I'm hoping that the descale might also help the water reservoir sensor, but it sounds like there may be a deeper problem as the previous owner reported shorting the sensor wires didn't help either.
Lastly, I'm thinking about descaling the boiler. I saw a youtube video where the boiler was filled, heated, and drained on it's side repeatedly until the water was clear. Anybody else out there give this a try? Looks like it would be easy enough.
Eventually this will get a full teardown, but not right now.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 8,194 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Vene. A1, La Cimbali M32 Grinder: Azkoyen Capriccio, Major Vac Pot: 40s era Silex Drip: Msl. Com. brewers Roaster: gave it a try, decided no
Posted Mon May 20, 2013, 2:16pm Subject: Re: Old NS Oscar descaling
The water to the HX system comes from the same tank as the water to the boiler. If the water level sensor pumped water into the boiler to refill it while the soultion was in the supply tank, you have soultion in the boiler.
There is a drain plug on the left rear of the boiler when standing in the operator position. You can remove the plug but it is a little messy as the plug is inside the case.
You could also just flush water from the steam wand like you would do to get hot water from the machine. No it is not a "documented" method but I seem to remember doing it but then again, that was a long time ago.
In real life, my name is Wayne P. Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!
Feed the newbs, starve the trolls and above all enjoy what you drink!
Posted Mon May 20, 2013, 2:28pm Subject: Re: Old NS Oscar descaling
Yeah, I started working with the HX side only with the solenoid for the boiler disconnected so no solution would enter there.
After seeing the "beautiful blue" rinse from the HX I decided that it was important that I tackle the steam boiler too. Right now it's full of a mild citric acid wash, and on the 3rd round. Still getting a little blue, so it will be a while before I get it all cleaned out. I've been using the method where you heat it up with the descaler in the tank. Disconnect all power, flip it onto it's steam wand side, and use the steam wand to drain the boiler. Seems to be working quite well so far.
In the meantime I'm noticing my Gicar controller has some issues noticing the level in the reservoir. Even jumpering the sensor connection on the controller doesn't work, so I'll have to send that out for service eventually if I can't trace the fault or don't want to mess with it.
Luckily there isn't a spot of rust at all on the frame. I've had it apart enough to clean all the dirt and debris. Also have some drain tubes that were misplaced put back in the proper spots.
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