Leaking expansion valve - Quickmill Silvano

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by pajohn »

Just picked up a QM Silvano from someone leaving the country. Great price, but didn't mention any issues... but I've replaced parts before, so not too worried.
I get it home, turn it on, and it starts steaming and sputtering once it starts heating up. I realise that the expansion valve return is leaking back into the reservoir. Starts with a drip when the PID temp says about 50C, then turns into a full stream around 80. I take off the expansion valve, and take it apart, there's a bit of scale on it, throw it in some vinegar, get it cleaned off, and throw it back in the machine. Adjust it to around 9bar with the portafilter blank. Turn the heater on, and same issue. I think my next move is to replace the expansion valve, but if anyone has other ideas, I'd like to hear them. Thanks!


#2: Post by pajohn »

Probably know this, but should mention the QM Silvano is a vibratory pump, HX machine (though I don't steam milk often, so that doesn't matter to me)


#3: Post by edgndg »

I'm generally handy around repairs, but am relatively new to tinkering with espresso machines. That said, I've owned a silvano for 6 years or so. A couple of things have gone wrong, and I've called Chris coffee and they've been really good about talking me through the diagnostics and repairs and sending the parts I needed. I did by my silvano there. Just throwing it out as it may be worth a call, and I think they may be the only ones selling these machines in US?


#4: Post by pajohn »

Yeah the modular nature of these machines makes them easy to work on if you're otherwise familiar with any other machinery. I bought a QM67 from Chris in the USA, but this one was second hand (220v over here). Already ordered a new valve from him, will revert if that doesn't do the trick. What issues did you have with your Silvano?


#5: Post by pajohn »

update: I was wrong, was not the expansion valve, but rather seems to be coming out the boiler intake, and pushing though the "air release valve"
(#70 here https://espressodolce.ca/user_manuals/Q ... -04005.pdf or part PL08700VA / "VALVOLA S1")
On Chris coffee, it says: "This valve is located directly after your vibratory pump. The symptoms of this valve malfunctioning is an excessive amount of water going back into the water tank while pulling a shot."
but, the water coming back is not when pulling a shot, it's when heating up (and heated up), or do we suppose same issue?


#6: Post by JRising »

Yes. That valve (Priming valve, bubbler valve) is supposed to let the pump prime even with air in it, it leaks back to tank when the pressure in the pump-outlet is very low and lets the bubbles through. Once the pump fills with water, the pressure goes way up and that valve closes. The outlet section of that priming valve has a tiny check valve in it, rubber plug on a spring like in the outlets of Ulka pumps. It seems that that little check valve has failed. You can take it apart and examine it for what's holding it open. If it's badly mangled, replace it.
https://www.chriscoffee.com/products/ai ... 5a9a&_ss=r


#7: Post by pajohn »

Thanks, yeah took it apart, looks ok, but obviously not functioning properly. Just going to replace it and cross my fingers.

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#8: Post by slipchuck »

Did you get this problem fixed?

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