Hi,

I have an issue for a some time, where my Oscar II doesn't start properly.

When I power the machine on, most the times the pump sounds not so powerful and a bit choking and the pump with this weaker sound continue trying I guess to pull water from the tank until it gives the whole UI flashing. So I have to turn it off then on again, and again, until the pump responds and pull water from the tank.

What could be the issue ?

I disassembled and re-assembled the machine more than couple times for cleaning purposes in citric acid, and other times in Urnex cafiza.

Hi wolfrose Fantastic video and interesting issue

Mr. Oscar II's Symptoms:

1. Steam Boiler:
   1. Steam Boiler can take several 90 second pumping sessions when starting up, but does fill and reach "ready" state eventually;
   2. Steam Boiler water-level-sensor probe does achieve continuity after several fill attempts upon turning on machine/fill Steam Boiler;
   3. Intermittent water pumping (does pump sometimes?) or slow fill of Steam Boiler over several 90 second pump intervals;
   4. Steam Boiler water-level-sensor probe not developing ground circuit continuity intermittently for full 90 seconds of pumping at times (boiler not getting water either as quickly as it should about 600ml/minute, or at all).
2. Pump Activity:
   1. Pump reported as sounding as though working to overcome a very high amount of resistance in the hydraulic system;
   2. Pump working for 90 seconds until safety timer shuts the pump and machine down to prevent pump overheating/coil-burnout;

Possible Causes to Investigate:

1. An elusive partial blockage in one of the fittings, hoses, or components in the Pump→to→2waySolenoid→Steam-Boiler hydraulic pathway;
2. The 2-Way Solenoid Coil may be weakened, inconsistently, (or possibly not at sometimes) energizing (little or no magnetic movement of plunger);
3. A possible Control Unit component fault such as Relay not energizing 2-way Solenoid consistently when pump is called/energized to fill Steam Boiler;

Looking forward to any updates from OP wolfrose on further checks internally

Hi again

And thank Mr WWWired very much for the wonderful support.

What I have done later this problem, I actually let the problem as is and didn't disassemble the machine.

All this, and I don't strongly assume that it's the case was in a bit cool weather, where I'm in Saudi Arabia, the area I live in, cool weather would be like 21-23 degrees. Now summer just started, the machine behaved completely differently. The machine now starts directly, the pump doesn't pump water anymore, just the pump happens when I starts extracting my espresso !

I think there's a problem with the pipes, or the solenoid valve.

The valve in the cup atop the boiler that's filled with water is the vacuum breaker.

It looks like the "leak" is from the steam boiler safety release valve, I'm guessing because the steam boiler is filled to the very top with water. This can happen when the water level sensor is coated with scale -- it acts as an insulator. No water detected by the water level sensor -> the controller tries to fill the (already full) steam boiler with more water, which ultimately leads to the steam boiler being pressurized with water (!!?). The steam boiler's safety release valve opens so the boiler doesn't burst (they're rated at ~2 bar).

I tested the both solenoid valves resistance and both are 890 ohms.

I disassembled the machine but I have no idea of what to check for the issue.




When I opened this screw, water went out, after I let the boiler water out and checked it's empty. I don't know maybe it's steam boiler left water.




I removed the boiler and rest of the connected pipes, hoping when I assemble it again, it may work ok:




I removed this part, first time, I think it's the boiler sensor, and I think there's some dirt inside; should I remove the insulating tape and check if it's working or not ? Because I remember throwing this whole part in cleaning process, one time with citric acid and the other time with cafiza cleaning powder. Maybe I ruined this sensor, but the heating element works ok.

I re-assembled the machine and when I turned it on, it got back to the old issue which is the choking pump sound !

What could be the issue ? The pipes are fine, if anything is not ok, it maybe the solenoid valves or the heating element sensor.

Update:

I did a couple attempts and eventually the machine worked ok, pulled water ok, maybe not perfectly, the sound wasn't very loud but it pulled water to the boiler.

The steaming worked better than before.

I would say things are ok for now.

Thank you all for the support

+10 for HB's fantastic assessment (and brilliant as always lol)

Fantastic Pictures and you're becoming an expert wolfrose with the Oscar II (and other high-end Heat Exchange espresso machines through this experience as these machines all share very similar engineering and design!)

Definitely pull and inspect your Water Level Sensor as HB suggests

HB wrote:The valve in the cup atop the boiler that's filled with water is the vacuum breaker.

It looks like the "leak" is from the steam boiler safety release valve, I'm guessing because the steam boiler is filled to the very top with water. This can happen when the water level sensor is coated with scale -- it acts as an insulator. No water detected by the water level sensor -> the controller tries to fill the (already full) steam boiler with more water, which ultimately leads to the steam boiler being pressurized with water (!!?). The steam boiler's safety release valve opens so the boiler doesn't burst (they're rated at ~2 bar).

Hi,

So, the machine was on the same problem with the low noise pump which we assumed that there's something resisting in the pipes or the hoses.

Then, the last thing happened is the extraction noise goes very noisy which is the first time I encounter this issue, and the temperature of the water is very high !

I thought one of two things, either there's a failing component in the system or the machine need more cleaning, even I cleaned the machine two months ago.

So I did the following:

1. Disassembled the machine again and used espresso cleaning powder:




2. I noticed some scale here and cleaned it:




3. This is the solenoid valve attached to the group head, this is as far as I could disassemble it and I didn't know what else to clean at this point, so I ended up putting it back together:



4. The second solenoid valve connected to the OPV, I didn't know how to open it, so I damaged its plastic housing a little bit in the red circle, then I figured out to remove the screw in the green circle, and also the same issue with the first solenoid valve which is I don't know how to clean it and I put it back:




5. The OPV kit: I didn't know how to clean it because it seems the parts are tightly attached, is there a way to clean it ?



6. This valve which is connected on the other side of the group head, and it seems it's formed inside in away to work with pressurized water I guess, I tried to pull air from both sides, but I felt to me it's locked and could work with pressurized water:









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Then I thought I cleaned the machine and it should work, so I reassembled everything and turned on the machine and this is the new situation:

1. The pump work and fill the boiler but not loud as the usual, the noise is low but it's better than before because it doesn't still choking for 90 seconds and then I turn it OFF/ON to push the machine to fill the boiler. It's less noise but fills the boiler with no obvious problem. At least for now.
2. The extraction doesn't work. When I press single or double shots, the machine doesn't output water.

Hi,

Good news

The machine is fixed now !

It turned out I had to clean the two solenoid valves with the OPV kit.

Now it's working almost like the new one.


Thanks all for the support.