samuellaw178 wrote:This is a bit mind-boggling though, still trying to picture how this could happen. I would have expected the pf to leak catastrophically (>60ml/30sec) for the piston to not have any pressure.

Agreed. I've put the gasket in upsidedown in the past and it did leak, albeit only drip drip drip. Similarly, I've had a damaged gasket and drip drip drip. (The gasket often gets damaged in my new Cremina because it is really hard to put in.**)... But never pressure issue. And I put up with it for months because it went days working perfectly and then of late started mucking up every 3rd shot, then second shot, then every shot, hence my frustrated post.

** re the gasket, I now heat it up before installing it and also lube the edges. Seems to help. I think the silicon are easier to install but they break when you take them out. Given I lube the piston 4 times a year this can mean 4 gaskets per year. Ridiculous. As I said the PF gasket, at least on my machine, is the only major, or even minor annoyance. I will solve this issue one day I'm sure for I'm committed to this machine for life (given the only other machine I'd use would be a plumb-in vintage spring lever and I don't have the space, capacity or inclination to do it where I live).

chopinhauer wrote:..given the only other machine I'd use would be a plumb-in vintage spring lever and I don't have the space, capacity or inclination to do it where I live

Gonna play the devil's advocate here... I've been using a supposedly 'plumbed-in' vintage spring lever without actually plumbing in for 2.5+ years now. A caravan pump from Ebay and a RO water tank made that a non-issue (I'm renting so it's not possible to plumb). Speaking of which, there's a really nice lever on sale on the other forum

OK, I admit it, I have been drooling over that machine for the past week, so I do have the inclination. But the lack of space, capicity, time and general logistics at my end (ie. my life's a bit crazy at the moment) outweight this. Oh, and 'common sense' (a rare commodity on this coffee-crazed forum where people don't think twice to buy both Monoliths) given I am already extremely well set up even by coffee geek standards.....BUT if my life changes and I find myself having to make more coffees than the Cremina can comfortably handle then, yes, it will be time to consider other options.

Sadly, after about a dozen or so coffees the problem is back, so clearly I didn't have the group gasket in upside down as I supected.

Yes, I'm thinking it has a lot to do with that gasket or the area in the group around it. The gasket is so hard to get in that it could be damaged so air could be entering the group on the pull. Or the gasket is fine, but the area around the shower screen is damaged, though that is hard to believe given it is made of solid metal (chrome? Brass? Stainless?). Or it's the lugs on the PF as dgary suggested, but this seems unlikely too as the machine is only 6 years old and has not been subjected to much punishment. I can test this though by using my new Naked naked PF for a while. Or it could be the area on the PF into which the lugs lock. But this one is harder to test and even harder to fix. Still given the difficulty of getting the group gasket in the last two are possibilities.

Anyway, I'm stumped and pissed off as its been going on so long and I've never seen mention of it on this forum.

Which basket are you using? Since the new group gasket solved your problem temporarily, could it be a worn basket rim exacerbating the issue of not sealing effectively?

Dose, tamp pressure & headspace? I have found if I don't leave adequate headspace (~1/4") I will sometimes get a softer, less firm, pull on tbe lever. Ditto for too much tamp pressure.

FWIW, I pull the lever up just short of water inject before inserting the portafilter.

Lastly, Olympia changed the piston seal (& group?) with the 2016 group to address issues with the prior gen group/piston/piston seal design. I don't know the impetus for the design change implementation though.

Thanks Dan for your thoughts.

I don't think it's the baskets as I alternate between a newish Elektra double and 6 y/o Olympia double. Rims look fine.

Headspace seems fine, as I use 16 grams in the Elektra and only 15 in the slightly smaller Olympia double. Definitely nowhere near the shower screen, and while your observations are correct, the Cremina is incredibly forgiving if you do over or even underdose. One just adjusts the pull.

As for your PF insertion technique, yes, I've heard this is commonly done. But I've been a simple point and shoot guy throughout my 20 years with manual levers (no Fellinis, double pumps, or timing when to put the PF in) and it has always, till now, worked for me. Of course, I do take care at every stage in the point and shoot process (especially inserting the PF and gently lifting the lever; nothing sudden or violent).

Robert, you're leaking pressure somewhere. How's the gasket that seals the piston rod at the top of the group?

Gary, I did change that gasket, brass washer and circlip that holds them in place about 9 months ago. I also changed the piston gaskets and PF gaskets 6 months ago. So none of these should be causing the problem.
I guess now, given that the problem is persisting no matter what I try, I should go back in a change everything again even if I suspect the culprit is just the PF gasket (which looked fine when I checked a few days ago, but could have hairline cracks).

When you had the piston out of the group bore did you inspect the wall of the bore for possible scoring or unusual wear pattern?

Strange, the problem disappeared for a # of shots and then returned. But I'm not telling you anything you don't already know

Sorry to hear that Robert. Maybe it is still the piston seal after all??

I thought of a possible quick test that you may try. Push the lever to the up position and leave it there. Then immerse the bottom half of the grouphead in a bowl of water. Then pump the lever down. Hopefully the piston works and it bubbles? If it doesn't there you can almost confirm it's the piston seals (or the piston) not doing their job.