shamblesuk Senior Member Joined: 30 Dec 2007 Posts: 13 Location: London Expertise: Just starting
Espresso: Gaggia Selecta Deluze Grinder: Dualit
Posted Mon Mar 12, 2012, 4:53am Subject: La Pavoni - uneven flow and pitting in puck
Hi all,
Recently upgraded from a Gaggia Classic (broken pump) to a pre-2000 La Pavoni. Going through the usual headaches getting used to the machine and having a consistent problem as below.
I'm getting poor crema and trying to eradicate some of the causes. I use a Dualit burr grinder and have a 49mm brass tamper (I'm not a true novice to coffee making) and apply the usual 30LB of pressure. But I keep getting this indentation every time I pull. This hole relates to the area closest to the boiler (about 9pm in the portafiler before I insert, so 12pm when inserted).
If I then take out the portafiler and watch the water flow, there is a definite difference between the flow toawrds the 'back' of the grouphead, it is much stronger than anywhere else and this relates to the area which has the marking in the puck.
I have taken out the grouphead and cleaned/scrubbed everywhere I can think of, but I cannot work out how to deal with this uneven flow.
TonyVan Senior Member Joined: 24 May 2010 Posts: 269 Location: Pacific Northwest Expertise: I love coffee
Espresso: GS/3, La Pavoni Grinder: Macap M7K, Rocky Drip: Kone
Posted Mon Mar 12, 2012, 6:04pm Subject: Re: La Pavoni - uneven flow and pitting in puck
This may sound too simple, but is there any chance there's some corrosion or other unevenness due to the dispersion screen? I ask this because even if there's uneven flow from the boiler inlet once the lever is raised, the pressure would seem too high to permit high/low flow areas over the screen's area.
Or - maybe a flaw in the surrounding gasket that would let some pressurized flow enter around the side and into the filter basket? The erosion from the grinds up the side of the basket have me grasping at that particular straw.
I remember a few years ago that gasket kits for the LP started including replacement screens. I'd chalked this up to the parts vendor(s) just upping the kit content and price, but maybe there's some degradation over time. I just can't recall seeing this problem on any of my pre-M's over the years - though I fully admit this could be more about not paying close attention to this possible phenomenon.
jtrops Senior Member Joined: 25 Dec 2008 Posts: 118 Location: Colorado, USA Expertise: I live coffee
Espresso: Gaggia Factory Grinder: Zass Turkish/Kitchenaid pro... Drip: Vietnamese pour over Roaster: Heat Gun/DB
Posted Mon Mar 12, 2012, 7:27pm Subject: Re: La Pavoni - uneven flow and pitting in puck
I have a millenium model (Gaggia Factory), and it seems to not suffer from this problem. That being said, I have read that slowly raising the lever and letting water into the group at a trickle can help minimize this problem. Like I said I haven't found the need myself, but it could be worth it to try.
The poor crema could certainly be due to the channeling in the puck. Another thing to consider is grinding finer, and using a much lighter tamp. I think the channeling should be resolved first, but after that I found that all of the advice about light tamps seemed to make a big difference for me.
Posted Wed Mar 14, 2012, 12:01pm Subject: Re: La Pavoni - uneven flow and pitting in puck
I'm a new owner of a used pre Millennim 49mm la pavoni professional & one issue I found was the shower screen didn't look on an even plane(possibly due to the piston set to low) So I undid the group & adjusted the height of the piston so it sits a little higher ,which leaves the lever sitting a bit higher in the down position. But now the screen looks like its sitting more level & I'm getting really nice shots.
Posted Sun Apr 1, 2012, 9:35pm Subject: Re: La Pavoni - uneven flow and pitting in puck
What is your boiler pressure? Is it possible that your temperature is too high and therefore your pressure too high? If so the extra pressure could be blowing past the piston seals.
hankbates Senior Member Joined: 2 Feb 2012 Posts: 30 Location: Yarmouth Port, Cape Cod, Massachusetts Expertise: I love coffee
Espresso: La Pavoni Professional... Grinder: LaPavoni Jolly Roaster: Hottop
Posted Tue Apr 10, 2012, 5:27am Subject: Re: La Pavoni - uneven flow and pitting in puck
Have you seen the explanation near the bottom of the page in the following link? Click Here (www.francescoceccarelli.eu) Depending on the age and flexibility of the lower piston seal, you may not be getting uniform flow to all areas of the dispersion screen...
brianmch Senior Member Joined: 1 Mar 2004 Posts: 107 Location: kc, mo Expertise: I like coffee
Espresso: Livia 90 Grinder: Mazzer Drip: French Press Roaster: Fav-Parisi, Kansas City
Posted Tue Apr 10, 2012, 6:51am Subject: Re: La Pavoni - uneven flow and pitting in puck
Make sure that your dose, distribution, and tamp are even and consistent. IDK your process, but if you're knocking the portafilter to even the cone make sure to do it gently up-down not side-side as this can shift puck formation away from the perimeter. If you knock too hard you can fissure the puck. Also, some machines are very sensitive to headspace...the manner in which the puck touches (or doesn't) the screen.
Also much clearance is there between your basket and your tamper?
My Livia is very sensitive to these things and requires a deliberate hand. Keep it up.
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