Posted Mon Jan 16, 2012, 6:48pm Subject: 2 Maximatic/Livietta machines w/unexplained difference in performance--CREMA
Greetings fellow Geekers,
I have recently completed a restoration of a 1983 Maximatic/Livietta and did some side-by-side comparisons with my previously self-restored 1984 Maximatic/Livietta. They are identical machines with no discernible differences (same size 49mm portafilter, same factory issued original Fluid-O-Tech pumps, P-stat calibrated on both to 1.1 bar). The same coffee, ground in the same grinder yields crema and tiger-striped shots in one but not in the other. I'm stumped as to how to get the crema in the other machine. What variable am I missing? Does anyone have any ideas?
The only thing I can think of is to install an expansion valve on the pump of the 2nd machine. But neither machine currently has an expansion valve. Also, I do not observe any faster flow on one machine over the other. Any thoughts and/or ideas would be appreciated.
Posted Sun Jan 29, 2012, 4:31am Subject: Re: 2 Maximatic/Livietta machines w/unexplained difference in performance--CREMA
Here is a 2 week follow up and solution found.
After taking the pump apart and checking the seals and swapping in a new pump with the same results I set out to identify the factor that was different on the two machines. After adding a Fluid-O-Tech bypass valve, further assessment revealed low pump pressure on the problem machine. I removed the flow restricter washer and that helped but did not solve the problem. Part of that same assembly includes a check valve that was clean and apparently functional. I removed this and reinstalled the flow restrictor washer and problem is solved.
Has anyone else encountered problems with this check valve?
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