Lately when I end a shot, pushing the lever down, the exhausting of pressure has become less than usual as in its not as aggressive a spurt as it used to be. And I'm getting residual pressure in the portafilter so that I get a hiss and sometimes a small sputter as I undo it from the group. Prior to this the puck would always be quite dry whereas now its quite wet and sloppy
The machine has recently (6 weeks ago) had all new group seals, descale and new pump. It gets backflushed with water daily and chemical flushed every couple of weeks or so.Its had several chem flushings recently in case it was residue causing the problem.
I have removed the exhaust valve, cleaned it manually and have done the same with the the mushroom and gicleur and behind the dispersion screen.They weren't dirty and nothing has changed.
The brew pressure gauge reads normal pressure around 9 bar when brewing and the speed of the shots is normal.
I feel like I'm missing something obvious.Can anyone help?Thanks.
Hi Colin, try to backflush with the blind filter, if the exhaust flow of water is "aggressive" same before maybe could be some modification in your brewing method, grinding, dosing, tamping or even the coffee freshness. Just my guess.
Thanks for the thoughts Giampiero. I've been using the blind filter to do all the backflushing and its exhaust flow is also a bit softer, although perhaps not quite as wimpy as the exhaust from a coffee pull. But worth noting is there's no residual pressure left in the blind portafilter.
Same small range of coffees as have used for past 12 months all within 2 weeks of roasting. But I'll check my dosing and tamping tomorrow with a suspicious eye and see if anything changes.
I've tried varying my method of brewing with no change....but there has been progress.
I dismantled the group head completely to see if there was anything obvious.Everything looked clean and the seals were as new.
After careful reassembly I noticed that after taking a shot and pressing the lever back down to its off position I could get more pressure released by putting a little sideways pressure on the lever. There's a tiny amount of play in the lever shaft ....enough to move the exhaust plunger a fraction more. A little more hiss of pressured water and no more residual pressure at the portafilter
To me this meant the exhaust valve is not opening quite enough.The cam and plunger/stem are definitely not worn. The exhaust valve and all the others has been replaced recently when it went in for service, but I'm now wondering if the replacement valve and its extension are not the right length. I read somewhere there are variations in length for different machines and its definitely possible the guys who were working on my machine may have put in generic parts that may be the wrong ones.
Can anyone please tell me what length those brass triangular section plungers that activate the exhaust should be for the Qmill Andreja Premium? ...or where I could find out?
ok at least you could eliminate the methods issue ;-) So do you mean that the issue has come out just after the group valve overhauling? Does the lever camme and extensions valves has been lubricate before re installed? Does the big oring which seal the lever spindle has been replaced and lubricate? No any leaking form exhaust valve while the machine is idle ON after a shot? The length of the lower extension of the brewing valve is 12mm and the spring 44 mm ( i have to change eye glasses) The length of the exhaust valve short extension is 12,5mm the triangle estension 32,5mm and the spring 45mm Extensions i took measurement from the edge of the valves not from the oring. Hoping useful for you. Have a good work.
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