Isomac Millenium - brew water temperature

[seansean]

I have had an Isomac Millenium (v1) for some years now and of late it has not been producing good coffee. In particular, it did not seem able to get the brew water up to heat. I stripped down the E61 group and it was in a terrible state; the mushroom at the top was full of scale and I am surprised that any water had been able to get through at all! I obtained a service kit, replaced all of the gaskets and seals and gave everything a good descale. I even unscrewed and descaled the heater element from the boiler. So now everything is back together and i have flushed everything through a number of times. However, I do not seem to be able to get the water up to what it used to be.

My normal routine would be to:
- perform a cooling flush, as after a few minutes idle the brew water would usually be up near 97 or 98 degrees(c)
- pull the shot; generally it would start the shot at 90 and finish at around 88 degrees(c), which was stable enough for me

Now, I am struggling to get the brew water coming from the head above 93 degrees(c). This is immediately that I pull the brew lever and then the temperature rapidly drops down to about 75 degrees (c) in the time it would take me to pull a shot. This is after the machine has been on for a couple of hours so it is not a warm-up issue.

The pressure dial on the front generally swings between 1.4 and 1.6 bar, though yesterday the machine has been on all day and walking past I noticed that the pressure guage was reading 2.0 bar! I pulled the shot lever and water came out at 96 degrees(c), dropping steadily from there. The pressure guage returned to about 1.5 bar.

Very confused .........

I have a thermo-couple attachment (http://users.rcn.com/erics/Adaptor06.pdf) fitted to the group head with an Omega digital reader, so I am confident i am reading the temperature correctly.

Does anyone have any suggestions?

Thanks

Sean

[sicinius]

What happens whne you adjust the temperature contol upwards??