I have a QM67 machine and having issues that sadly weren't solved with a professional service. I'm losing pressure in the brew boiler, it seems to discharge itself to empty and gauge shows no pressure. Only when I drain some water through the steam boiler does the main boiler refill then heat comes to temperature and pressure before going the same cycle again of draining and zero pressure. Annoying as it gives a short window of making a brew. Any advice appreciated. I'm far from any city or service agent so looking for support in basic newby espresso terminology. Thanks in advance.

If I understand what you're saying, the brew boiler isn't perfectly sealed when idling. The boiler (At a temp slightly higher than boiling) is allowing the water to boil to steam and the steam is displacing the liquid water out of the boiler somewhere.

That water has to be going somewhere, finding it is step one.

Put a spoon behind your control lever so that the machine runs the pump without you actually raising the lever. If you get flow from your E61 drain or out of the group while doing this with the brew valve closed, then your brew valve leaks.

If it's not the brew valve, feel the pipes between the pump and the t-fitting where brew circuit separates from steam circuit. If those pipes near the pump are very hot (warm is fine, but painfully hot to touch is bad), the check valve before your brew-boiler is leaking and allowing water to back-flow toward the pump.

There's probably a couple possibilities I'm not thinking of, but those first two are the common ways for a brew boiler to lose it's liquid water.

Thanks JRising. I'll try these steps this evening.

The liquid is being discharged back into the reservoir through the brass fittings and tubing behind the pump and exiting into the reservoir by the shorter overflow tubing. No obvious water escaping the machine itself. Yes very hot to touch, especially the brass T joint.

Photo of expelled liquid route from brew boiler

Good job.

Okay, Blue Circle is steam boiler stuff only, we can probably ignore that.

If you can trace the constant leakage to the Brew Boiler's OPV (Red Circle), then we can assume it is held open by scale or the rubber valve face in there is decayed and useless. If the leak traces to this, it is removeable, cleanable and examineable. Be sure to take out the set screw (silver philips in the side, above red circle in pic... I shoulda put in an arrow) before trying to unscrew the innards from the valve. You'll see how it works when you see what's in there.

Good luck, Bro.
If you need the valve it's OT0990VE

https://www.espressoplanet.com/Expansio ... 990VE.html

Thanks for the response. I wasn't sure what you meant by red / blue circle?? Did I miss a picture?

I'm going through a thorough repeated descale rinse right now using Urnex coffee and espresso descaling powder, and it still seems to want to do the discharge cycle possibly not as frequently but cant be sure.

Much appreciated!!!

JRising, I'm accepting the fact I will now try and see the state of the expansion valve. I've removed the philips screw and would assume trying to remove / unscrew the large flathead internal part of it? Using a spanner around the outside of the valve unit I've tried with pretty good force to unscrew but to no avail. Am I heading in right direction? I could disconnect hose and pipe attaching to the valve and remove it from the machine to apply better force but hoped to avoid this. Thoughts... Thanks