Isomac Millenium Brew Pressure Issues

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

#1: Post by RZ730 »

Hey Guys,
I've have the feeling that I've searched the entire forum but I just can't find a solution.

I am quite new to the espresso game and recently received an old Isomac Millenium (E61).

Since day one it seemed to never really get up to pressure. I therefore bought and installed a pressure gauge which indicated around 6 Bars of pressure against a blind filter, so I adjusted the OPV and it hit 9 like it should.
I then tried to pull a shot: 6 Bars, maybe my grinder setting was wrong so I cleaned the shower screen and back flushed it with a blind filter, 6 Bars.
I then adjusted rhe opv again: 6 bars in every setting.

At this point I thought the machine is about 20 years old, maybe it's time for a proper cleaning, so I descaled it: 9 Bars, second try 6-7 Bars, all this time the opv was releasing a lot of eater back into the tank.
So I took the opv apart, inspected everything, cleaned it, reassembled it and tried again: No matter what position it was in, the pressure never surpassed 7 Bars.
Since this couldn't be normal I went out and bought a replacement for the OPV and new silicone lines, installed everything and tried again: 8 Bars in the stock setting. At last some progress! I tried to adjust the OPV: High flow to the tank, took extremely long to (very slowly) build pressure, after around 40s ot peaked at 9 Bars, but only very briefly before the machine switched the heater back on and the pressure dropped to 8.6 Bars. I tried to adjust the opv further but no matter how I adjusted it it would never reach 9 bars again, 8.3 at best. High flow from the OPV since the moment I first installed it. When trying to pull a shot absolutely no pressure builds up but that might be me.

While it looks quite crusty I don't think that it's the pump as there is plenty of pressure to open the OPV but it would explain the extremely slow pressure build up.

I'm out. No ideas anymore what this could be.

Any suggestions, advice and/or referrals to other posts with similar issues would be greatly appreciated.
I hope I didn't waste your time and that my post makes sense as English isn't my first language.

Thank you very much in advance!
Joachim (You can call me Jo/Joe)

User avatar

#2: Post by cafeIKE »

How much water do you get out of the group in 30s with no portafilter inserted?

What is the pump model and build date?
It's quite possible it is the problem

RZ730 (original poster)

#3: Post by RZ730 (original poster) »

Hi, should be an Ulka EX5, I will check the flow rate tomorrow morning and report my findings back to you as my family is now asleep!

User avatar

#4: Post by stefano65 »

Check in addition of the OPV the bleeder valve attached to the pump,
in other words,
do you see water coming back into the reservoir?
if yes then the issue is ether one fo the valves mentioned above,
if not, it can b everything else in the brewing circuit before and after them.
Stefano Cremonesi
Stefano's Espresso Care
Repairs & sales from Oregon.
★ Helpful

RZ730 (original poster)

#5: Post by RZ730 (original poster) »

Ok I just tested the flow rate of the pump and I got 120ml/30s, not looking too great there, and after taking a closer look, all of the water that goes back to the tank is leaving the bleeder valve, the water in the tube from the opv doesn't even move..

Seems like you were both spot on, this machine probably wasn't taken care of since the day it was made...

Sorry for wasting your time, should have paid closer attention.

Thank you very much for the advice, I will order and install the spare parts and then see what else is broken on this thing..

RZ730 (original poster)

#6: Post by RZ730 (original poster) »

So the parts arrived today, installed them and everything is perfect! Again thank you so much for your help!!