I just replaced my group head gasket today hoping to resolve a problem. It has lessened this problem it but not eliminated it. When the extraction is taking place the portafilter shoots a single streams of coffee in random direction, this occurs with any tampering pressures on grounds. I also get a bit of leakage dripping on the outside of the portafilter. The extraction is much lighter than it use to be and when I back flush, the group head seams to be under such great pressure it blows around the gasket, pulsing to the pumps cycle, and blows water/steam on the outside of the portafilter. This is a HX Bezzera 99/s machine. I wonder if the pump pressure is too much? Would the 3 way solenoid cause this? But, it had worked fine just 2 weeks ago. Any feedback would greatly be appreciated!! dave
--Apple-Mail-7--189089820 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset -ASCII; delsp=yes; format=flowed I have a Livia 90A, which I understand is Pasquini's rebadged Bezzera. I notice that sometimes when using a bottomless portafilter I will get random pinpoint sprays of plain water spraying diagonally from the perimeter even if there is a perfect tiger-stripe cone brewing down into the cup. I assume this must be the result of channeling, but I try to do whatever I can to make sure there are no spots in the puck where water can descend without resistance from the coffee. I too notice that varying tamp pressure, dosing, distribution and avoiding tapping seems to make no difference. But it doesn't seem to occur with a spouted PF--except if I've been lax about brushing out the gasket area, I might get some dripping around the sides. On Feb 13, 2007, at 11:41 AM, dave wrote: <Snip> Sandra Andina www.sandyandina.com --Apple-Mail-7--189089820 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset O-8859-1 I have a Livia 90A, which I = understand is Pasquini's rebadged Bezzera. I notice that sometimes when = using a bottomless portafilter I will get random pinpoint sprays of = plain water spraying diagonally from the perimeter even if there is a = perfect tiger-stripe cone brewing down into the cup. I assume this must = be the result of channeling, but I try to do whatever I can to make sure = there are no spots in the puck where water can descend without = resistance from the coffee. I too notice that varying tamp pressure, = dosing, distribution and avoiding tapping seems to make no difference. = But it doesn't seem to occur with a spouted PF--except if I've been lax = about brushing out the gasket area, I might get some dripping around the = sides. On Feb 13, 2007, at 11:41 AM, dave wrote:
Dave sounds like in incomplete seal. There is probably dirt under the new gasket between the metal and the gasket. Remove the gasket cleat it and the metal surface it faces on. Also not sure about your gasket but some have an upside and a downside. If so make sure it is oriented correctly and then re-install.
clean it not cleat
If it won't clean, then cleat it. Beat it into submission. Then install a new gasket that will have a complete seal.... Brett On 2/13/07, Barry Luterman wrote: <Snip> -- Cheers, Bretthttp://homeroast.freeservers.com
If it jams force it, if it breaks it needed replacing anyways. At least that is what they told us in the Army.
Dave, Your new gasket probably has some printing in raised rubber (numbers and such) on one of the flat sides, that is the side that should go up, into the group head......the smooth (no printing) side is the one that the portafilter should come up against. The gaskets frequently have one chamfered radius...again that is the edge that should go up, into the group head. Cleanliness in the metal areas that recieve the gasket is of paramount importance to not having leakage coming from around the outside of the PF sealing surface. The pump pressure shouldn't have changed substantially for no reason. When backflushing do you hear the normal pressure release into the drain tray when you stop the pump?....if so, the three way valve is probably working correctly. Does your machine have a brew pressure gauge?....if so, you will probably see slightly higher(1/2 bar or so) pressure than during a pull when backflushing. It really sounds like removing the PF gasket, doing a thorough (and a little more) cleaning, replace the gasket....ensuring correct orientation.......should correct the problem. If not - - another email to the list. Mike (just plain)
What kind of machine? You could be grinding too fine or over filling the basket. Lower model krups use this method as their pressure release valve.
I sure love your posts, Mike. I wish I knew some (any?) of all the interesting things you know.... Brian On 2/13/07, Michael Dhabolt wrote: <Snip>
Mike(just maybe not so plain), Thanks again for your expert advice!! Dave On Feb 13, 2007, at 4:24 PM, Michael Dhabolt wrote: <Snip>
Dave, Advice isn't worth much if it doesn't solve the problem. Fixed? Mike (just plain)
Mike, Thanks for checking back. I still have the same problem but the gasket doesn't leak now. The shots blast out of the gasket, blonding almost immediately and spraying coffee all over. The coffee moves over the bottom of the naked portafilter randomly and no longer forms the small steady stream it once did. Temp/grind/tamp doesn't change anything here. I might take the output tube off to see how much force the pump is applying. Know any good people who would fix this beast? thanks again!! Dave
Mike(just plain), Bezzera sent me this response to my problem.... Hi dave, The pressure during the brewing is the pressure necessary so that the water overcome the coffee resistence. So if the coffee is made in 5-10 seconds, it means that the coffee resistence is not enough, there is something wrong in the coffee milled. Then the temperatures of water to make a coffee could be too high or the pipe line is blocked. You have to check: - the pressure of the pump with a special filterholder with gauge - the boiler pressure (1- 1,2 bars it is correct) putting a gauge on the steam hose - the flow rate without the filterholder (at least 250/300 cc/min) If the machine worked well, means that now one or more of this parameters it isn't exactly. Hoping to help you, my best regards. G.BEZZERA Pietro Roscio Can you tell me if these gauges are available? thanks dave
PF mount pressure gauges are available places like Espresso Parts NW or Chris's Coffee Service. If you're following good HX temp management technique you should be able to tell if boiler pressure has changed since HX surf will have changed. Kona Kurmudgeon miKe mcKoffee URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must first not know. And in knowing know I know not. Each Personal enlightenment found exploring the many divergent foot steps of Those who have gone before. Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/ <Snip>
Dave, I've sent you an email - off list. Let's continue the discussion that way. Mike (just plain)