Hello All:

Wishing everyone a safe and Happy Thanksgiving.

I have a few quick questions regarding an olympia coffex I recently purchased.

(1) Thinking about replacing the pump on this machine. It's an ULKA not sure of model but it has an all plastic fitting instead of brass. Can someone point me to the operating flow rate of the ULKA pump? Reason I ask is that I have to adjust the grinder a few setting coarser and dose less to get the same output as I do on my cremina.

There is no blockage so I'm thinking that maybe the pump needs to be replaced because I think the flow rate is lower than it should be but it should be measured first.

(2) As far as replacement pumps I would like to replace it with an FOT but I believe a diode needs to be purchased from radio shack or else where since the diode is not included in the voltage connector.See link below.
FOT Pump
http://www.espressoparts.com/110v-70w-f ... atory-pump

ULKA Pump
(3) I think this is the correct ULKA pump. If replacement is needed I'll probably buy this one (ULKA EX5)unless someone else can chime in and recommend a different ULKA pump. I did see the one with the plastic fitting EP5:

http://www.espressoparts.com/120v-ulka- ... -vibe-pump

Thanks in advance

OK so a quick search yielded DrGary's post about the coffex:

Olympia Maximatic Restoration Notes

The prices of the FOT pumps have gone up.

DrGary I'll have to read the thread to see how the diode is connected.

From Erics graph

Unreliable Ulka pumps

So with no pressure if I am reading correctly the should produce 645 ml in one minute. I'll let it run for 20 seconds and take 1/3 of the 645ml to see if I come close to 215ml.

If I am not getting that flow rate does it mean the pump should be replaced assuming no other obstruction?

Found a replacement pump:

From 1st line:

http://www.1st-line.com/store/pc/Ulka-P ... 9p4337.htm

If I am not getting that flow rate does it mean the pump should be replaced assuming no other obstruction?

Not necessarily.

These machines are originally fitted with a restrictor downstream of the pump which is ABOUT the size of an E-61 gicleur. There is a thread somewhere where I participated in a discussion about this but searching would take a while.

Measure the flow (do it twice or thrice) and report back

Thanks Eric. I measured it twice. First time it was 240ml 20 seconds. Second time almost the same 235 ml 20 seconds so I'm not sure why I have to change the grinder all that much compared to the cremina with the same beans. The group is a 49mm group.

I also did adjust the pressure stat on this machine (it was changed to a mater pressure stat by Cerini's at some point from the previous owner). It came in a little high about 1.2-1.3 bar. I adjusted it downward to 1.1 bar. My cremina's boiler pressure stat is at 0.9-1.0 bar.

Well not sure it is the pump but I have to rotate 5 steps counter clockwise or coarser on my HG One and dose 14 grams to get the same output (27 grams/27 seconds) from the maximatic as opposed to dosing 15.5 grams and 5 steps finer on the cremina. Same coffee.

The pump flow unimpeded comes out close to what it should be according to the specs/graph provided by Eric. Maybe it's just the way the two groups are designed. I haven't used the maximatic in a while but it seems like the machine prefers a lower dose (14 grams-15 grams max) than the cremina. I would have thought that I should get the same output at the same grind setting by compensating with a lower dose but I was wrong. It stalls completely when I do this (14 grams same grind setting as cremina).

Guess it doesn't hurt to swap out for a new pump. Good to have a backup anyway. I'll check out the flow restrictor (gliceur).

Or you could just adjust the grind 5 clicks and not change your pump just yet.

Ed -

I would not change the pump. While that flowrate is a tad high, keep in mind that all of these pumps have a flowrate tolerance. My graph was based on published data that was also the mean flowrate.

I would inquire/look for a restrictive orifice in the vicinity of the check valve just after the pump output.

HBfencing wrote:Well not sure it is the pump but I have to rotate 5 steps counter clockwise or coarser on my HG One and dose 14 grams to get the same output (27 grams/27 seconds) from the maximatic as opposed to dosing 15.5 grams and 5 steps finer on the cremina. Same coffee.

Are you using the same PF basket? I have found in my experience that two identical baskets still varied greatly and therefore needed to be dialed in separately.

Thanks Scott. Yes the same pf basket. Since both machines have a 49mm group I just swapped the Richard Penney PF with the same elektra basket I had in there.

I've just come to the conclusion that the difference in the groups is causing the biggest impact in grind settings. Didn't think it would be as far off as I've experienced but I probably should have run them back to back in somewhat similar conditions instead of the morning of and afternoon of. That probably had something to do with it as well (maybe humidity was greater in the afternoon etc..)

I still prefer the manual lever process though but the maximatic is better for a crowd.