Hello,

I am trying to understand what happened to my ECM Mechanika IV after I refurbished the grouphead with new seals and cams.
I have a Coffee Sensor thermometer and always had a idle grouphead temp of around 93° at 1.25 bar.

After the rebuild I think I got a thermosyphon stall and the machine was idling at 80°, so I started checking things around and I noticed the anti vacuum valve was stuck on closed position due to scaling. I don't know how long this has been going on, so I unscrewed it, descaled and put it back and now it's working fine, closing with some drips when the boiler pressurizes.

Now at 1.25 bar the grouphead idles at 97° and I have to flush a lot, 120ml at least to get it down to 93° for extraction.
I only needed a short flush before fixing the valve, so I also cleaned the pressostat (looked ok but I descaled anyway) and still same temp.

So I turned down the pressostat quite a bit to have the grouphead idling around 93°and I have to keep the boiler pressure ranging between 0.6 and 0.8 bar. I don't do milk based drinks so I don't care about steaming but the issue is that the machine takes almost double the time to get to brew temp.
I can fix this by turning it on earlier but something still seems off.

Can anyone help me understand what is going on and how can I get things back to how they were before?
Thanks!

ppaolo2 wrote:I am trying to understand what happened to my ECM Mechanika IV after I refurbished the grouphead with new seals and cams.
I have a Coffee Sensor thermometer and always had a idle grouphead temp of around 93° at 1.25 bar.

One guess is that you introduced a minor leak over the brew valve when you were replacing the cam and seals. You have to have at least one of the valves out to put the cam back into place, but I would assume you had all of the easily accessable parts out. If there's a leakage over the brew valve, the water in the heat exchanger could be continuously heating to higher than boiling temp and steam flowing out toward the brewhead. Instead of being trapped in the thermosiphon loop(entirely upstream of the gigleur), warming the head a little and trickling back to the heat exchanger, the steam is escaping the head(passing through the gigleur and heating everything as it expands and escapes un-noticed) heating it above the expected thermosiphon temp.

In addition to the cam, which seals did you replace? Did you clean and inspect the valves?
What prompted the replacement of the cam? was it leaking past the seals and dripping at the lever end while brewing?
If you run the pump with the control lever in the down position (by holding the button behind it) for about 10 seconds, do a few drops appear at and drip from the head or drain-valve?

Thanks for your reply, I replaced all valves, seals, teflon gaskets and cam, it was a complete rebuild.

The machine is 8 years old, seals were hardened and weak and definitely in need of a replacement, brass parts were not too worn out but since I got the full kit I rather replaced everything. Before the rebuild I had no big leaks apart from some dripping from exhaust.
I had a doubt about the mushroom seal that looked a bit too small, so I put some teflon tape between the mushroom and the seal to increase seal strenght but no change in temps.
I will try tomorrow to start the pump with lever in down position and see if there's any dripping.
In what parts of the grouphead should I look for leaks ?

I tried starting the pump with the lever in down position, I didn't see any drips coming out from grouphead or drain valve.
Anything else I can check?

Well, that pretty much ruled out the leaking brew valve thought, so I'm out of ideas for now. Sorry.

NP, thanks anyway! Anyone has any suggestion about a fix ?

So I had a look around some forums and it looks like a E61 group idling at 97c isn't unusual at all in a HX machine after staying on for a while. Probably the stuck anti vacuum valve was in some way mitigating temperature at the group.

Now I keep a low pressostat going from 0,7-0.9 bar to have it idling at 94c so I don't have to flush too much given the fact that I use bottled water and it doesn't take too long to get to temp.
So I was wandering, what's the reasoning behind having such an high group temperature on factory setting, given the fact that coffee is usually brewed between 90/95c?
Maybe to have the possibility to pull many shots in a row?
So in my home where I just pull a shot and turn off the machine, how should I set it? Go for a long flush but wasting water or just keep a low boiler pressure for ease of use? Is there any cons in term of brewing quality?