Our two year old LaMarzocco GB/5 2EE, is giving us trouble. The 2 groups are not brewing at the same rate. It makes it near impossible to dial in a perfect grind setting when one side consistently pulls faster than the other. It can vary as much as 5-10 seconds brew time between groups. Watching the pressure gauge, both sides appear to be running at about 10 bars of pressure. The faster side might be running slightly under 10, maybe 9.8 bars. Could that have anything to do with it? But, wouldn't lower pressure mean a slower shot? Or is it something else?

I'm an experienced barista and the trainer for my company and I'm trying to understand more about how machines actually function and how to troubleshoot such problems. It is maddening to work on this machine and have such differences between shot to shot. I feel confident that the problem is not packing, dosing or tamping related, i.e, it's not channeling that's creating the fast shot. I have been seeing some muddy pucks though. We've had technicians look at the machine and they cannot accurately diagnose the problem either.

Has anyone else encountered such an issue? On a GB/5 or any other machine? What can be causing this and how can we fix it? Thanks for your insights.

Just want to serve the best shot possible,
LL

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I know with some machines the flow rate is adjustable on each group - I suspect this could be the problem. Adjusting the flow rate would rectify this particular problem. Testing with an empty portafilter would confirm this, and at the same time eliminate those human factors you mentioned (dosing, tamping etc).

With my old Faema (volumetric), pressing the button on one group would produce the same volume of water as the corresponding button on the other group, but it would pour in nearly half the time.

To be honest, I cannot imagine any other factor (other than a blockage in one group - unlikely) that would cause this problem.
You say your machine is two years old...have you followed La Marzocco's preventative maintenance schedule? You may have some scale build up or a slight blockage in one group. Also I find that around 9 bars of brew pressure is optimal for proper extraction.
I second the 9 bars and the slight blockage on one of the group heads. I would also check the rubber seal on the group head as well. To check if its the rubber seal, look to see how for to the left the portafilter handle sits on the group handle. It should be center or slightly left of center if looking directly at the machine. Good luck with that!
this sounds like you have a bad kanuter (thats ka-new-ter) im afraid these are irreplaceable and you should probably sell the machine to myself being a proper tech and all.


to be honest id say your going to have fun with this one i've never taken apart a gb5 group head but they are different than the other lm groups in the fact that the flowmeter in the semiauto is built in with the brew valve on the top of the brew group if you have non semi its just got the brew valve, the tubes running too and from the valve get calcification build-up sometimes.
id say its build up somewhere flow restricter maybe check the screw that holds in the brew screens remove that and back wash like no tomorrow if that dosen't work well g/l

group gasket wear hasn't much to do with shot volumes or times check with out the p/f in place and see that the other runs slower than the other just put a measuring cup under it.
Sounds like a clogged gicleur in the group - Common for machines with heavily restricted flow (.6mm)
Hi Ms. Lita! Haven't seen any videos from you in a while... whassupwitdat?

Anyway...

For a two-year-old GB/5 2EE, there are three different possible "flavors" of plumbing that you could have.
1) old banjo-tube w/external solenoid groups (carry-over from the Linea)
2) Piero-Caps w/teflon flow-restrictor/gicleur
3) Piero-Caps w/ruby-tipped flow-restrictor/gicleur

On any of these, the problem and solution are pretty much the same, though if you've got a #2 setup, you'd wanna switch-out the flow-restrictors to the #3 ruby-tipped ones. Come to think of it, if you have a #1 setup, you'd wanna upgrade to the Piero-Caps as well (#3 setup).

Simply put, your flow-restrictors, a.k.a. "gicleur" (Frenchie for "jet") are a little screw with a very small hole in it that purposefully plugs up most of the flow, so that when you're brewing coffee, it forces the water pressure on the coffee to build-up much more slowly, which has all sorts of effects on the extraction. Overall, it's pretty much always gonna be an improvement over a non-restricted setup.

The downside to having a heavily restricted flow machine is that when you have a hole, say, with a 0.6mm diameter, it doesn't take very much to mess up the flow through that orfice, be it from a random particle of coffee, scale (calcium) build-up, or from physical damage to the orfice itself.

On the old machines (a.k.a. setup #1 above), the flow-restrictors were little brass screws, which were susceptible to scale buildup.

On the #2 setup, people got smart and made them out of Teflon, which doesn't attract scale buildup. The problem was that it was really hard to get a consistent orifice size with such a soft material.

Then they switched to a synthetic ruby-type material for the part with the hole. The "body" of the gicleur is made of metal, but the "tip" is a flat disc of red stuff with a hole in it. Scale-resistant, and easier to make consistent orifice sizes with. Yay!

My guess is that you have a #2 setup from my list above.

Test: put an empty portafilter in the group (double spouts with the basket in it but no coffee) and put a couple shot glasses under it. Punch on the group and time how many seconds it takes to fill those glasses. Then do that with your other group. Is it different? That's gonna be a difference between your flow-restrictors.

Hope this helps!
Nick
Really they had old banjo's on gb5's thought they were all piero

Nick Cho said:
Hi Ms. Lita! Haven't seen any videos from you in a while... whassupwitdat?

Anyway...

For a two-year-old GB/5 2EE, there are three different possible "flavors" of plumbing that you could have.
1) old banjo-tube w/external solenoid groups (carry-over from the Linea)
2) Piero-Caps w/teflon flow-restrictor/gicleur
3) Piero-Caps w/ruby-tipped flow-restrictor/gicleur

On any of these, the problem and solution are pretty much the same, though if you've got a #2 setup, you'd wanna switch-out the flow-restrictors to the #3 ruby-tipped ones. Come to think of it, if you have a #1 setup, you'd wanna upgrade to the Piero-Caps as well (#3 setup).

Simply put, your flow-restrictors, a.k.a. "gicleur" (Frenchie for "jet") are a little screw with a very small hole in it that purposefully plugs up most of the flow, so that when you're brewing coffee, it forces the water pressure on the coffee to build-up much more slowly, which has all sorts of effects on the extraction. Overall, it's pretty much always gonna be an improvement over a non-restricted setup.

The downside to having a heavily restricted flow machine is that when you have a hole, say, with a 0.6mm diameter, it doesn't take very much to mess up the flow through that orfice, be it from a random particle of coffee, scale (calcium) build-up, or from physical damage to the orfice itself.

On the old machines (a.k.a. setup #1 above), the flow-restrictors were little brass screws, which were susceptible to scale buildup.

On the #2 setup, people got smart and made them out of Teflon, which doesn't attract scale buildup. The problem was that it was really hard to get a consistent orifice size with such a soft material.

Then they switched to a synthetic ruby-type material for the part with the hole. The "body" of the gicleur is made of metal, but the "tip" is a flat disc of red stuff with a hole in it. Scale-resistant, and easier to make consistent orifice sizes with. Yay!

My guess is that you have a #2 setup from my list above.

Test: put an empty portafilter in the group (double spouts with the basket in it but no coffee) and put a couple shot glasses under it. Punch on the group and time how many seconds it takes to fill those glasses. Then do that with your other group. Is it different? That's gonna be a difference between your flow-restrictors.

Hope this helps!
Nick
Bill Warnock said:
Really they had old banjo's on gb5's thought they were all piero
(assuming I understand what you're trying to say)

Nope. GB/5's had Linea-like banjo tubes for at least the first year, maybe two. Thank God for the Piero caps, eh?
Hi Nick et al!

Thanks for all the advice! My technician and I did take the groups apart and discovered blockage in the flow restrictor, which he cleaned out and seems to have corrected the problem, at least in the short term. I have not been on the machine for a couple weeks (been out of town) but will check on it later today. The last time I did use it, however, it did seem to be slowly reverting back again. I'll post an update asap and look forward to the benefits of all your expertise.

Nick, thanks for the question about my videos. A couple things have delayed my process, including technical difficulties with editing plus a death in my immediate family this year, which seriously knocked the wind out of me for quite awhile. However, with the Western Regional right around the corner, I am getting fired up and geared up again. I hope to have at least one new installment up sometime this month and more to come after. Thanks for watching and stay tuned!


Nick Cho said:
Hi Ms. Lita! Haven't seen any videos from you in a while... whassupwitdat?

Anyway...

For a two-year-old GB/5 2EE, there are three different possible "flavors" of plumbing that you could have.
1) old banjo-tube w/external solenoid groups (carry-over from the Linea)
2) Piero-Caps w/teflon flow-restrictor/gicleur
3) Piero-Caps w/ruby-tipped flow-restrictor/gicleur

On any of these, the problem and solution are pretty much the same, though if you've got a #2 setup, you'd wanna switch-out the flow-restrictors to the #3 ruby-tipped ones. Come to think of it, if you have a #1 setup, you'd wanna upgrade to the Piero-Caps as well (#3 setup).

Simply put, your flow-restrictors, a.k.a. "gicleur" (Frenchie for "jet") are a little screw with a very small hole in it that purposefully plugs up most of the flow, so that when you're brewing coffee, it forces the water pressure on the coffee to build-up much more slowly, which has all sorts of effects on the extraction. Overall, it's pretty much always gonna be an improvement over a non-restricted setup.

The downside to having a heavily restricted flow machine is that when you have a hole, say, with a 0.6mm diameter, it doesn't take very much to mess up the flow through that orfice, be it from a random particle of coffee, scale (calcium) build-up, or from physical damage to the orfice itself.

On the old machines (a.k.a. setup #1 above), the flow-restrictors were little brass screws, which were susceptible to scale buildup.

On the #2 setup, people got smart and made them out of Teflon, which doesn't attract scale buildup. The problem was that it was really hard to get a consistent orifice size with such a soft material.

Then they switched to a synthetic ruby-type material for the part with the hole. The "body" of the gicleur is made of metal, but the "tip" is a flat disc of red stuff with a hole in it. Scale-resistant, and easier to make consistent orifice sizes with. Yay!

My guess is that you have a #2 setup from my list above.

Test: put an empty portafilter in the group (double spouts with the basket in it but no coffee) and put a couple shot glasses under it. Punch on the group and time how many seconds it takes to fill those glasses. Then do that with your other group. Is it different? That's gonna be a difference between your flow-restrictors.

Hope this helps!
Nick
Lita Lopez said:
My technician and I did take the groups apart and discovered blockage in the flow restrictor, which he cleaned out and seems to have corrected the problem, at least in the short term. I have not been on the machine for a couple weeks (been out of town) but will check on it later today. The last time I did use it, however, it did seem to be slowly reverting back again. I'll post an update asap and look forward to the benefits of all your expertise.
Lita, generally speaking, it usually works better to just replace the flow-restrictors rather than cleaning them out. Scale attracts scale, and by irrigating (trying to poke or scrape out the stuff from) the orfice, it's very easy to mess up the size or shape of the orfice, as well as it's hard to irrigate it properly in the first place.

Good luck, and looking forward to new videos!

Your fan,
Nick
Yes. I just got home from working on this machine and the problem has returned, even worse than before! AiAiAi! I had tried your suggested empty portafilter test previously and did so again today. The difference between the groups is unbelievable. So, it looks like replacing the flow restrictor is a necessity. Thanks again!

Nick Cho said:
Lita Lopez said:
My technician and I did take the groups apart and discovered blockage in the flow restrictor, which he cleaned out and seems to have corrected the problem, at least in the short term. I have not been on the machine for a couple weeks (been out of town) but will check on it later today. The last time I did use it, however, it did seem to be slowly reverting back again. I'll post an update asap and look forward to the benefits of all your expertise.
Lita, generally speaking, it usually works better to just replace the flow-restrictors rather than cleaning them out. Scale attracts scale, and by irrigating (trying to poke or scrape out the stuff from) the orfice, it's very easy to mess up the size or shape of the orfice, as well as it's hard to irrigate it properly in the first place.

Good luck, and looking forward to new videos!

Your fan,
Nick

Hey all... this is a really interesting thread... I have a similar issue with a 3grp 2007 GB5 AV model... however, the middle and rightmost groups run at the exact same flow rate e.g. reaches required volume in 26 secs whereas the leftmost group runs fast e.g. reaches required volume in 19 secs. This is consistently the case, was thinking if it was scale it would cause one group only to slow down rather than speed up... wondering if it is still scale buildup why the two slower groups run at the exact same rate.

Any ideas what would cause the one leftmost group to run fast?

Thank you very much!

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