Actually I understand that the cylinder liners are made of polyphenylene sulphide. The polymer pistons that La Pavoni used for several years were also made from this material. A rigid and thermally resistant polymer is required here, and poly tetrafluoroethylene (Teflon) is not rigid enough.

hi guys, the guy i purchased the machine off de-scaled the machine before i baught it, and i probably wont need to ever do a de-scale as i live in a soft water area,
stripped the grouphead down today and replaced all the seals including the piston sleeve seal, was all very easy, once i made a tool to unscrew the plastic sleeve it came out very easily, and glad to say the dripping has stopped and i can also feel a great difference in the pull, very happy with the results, found some high tac food grade silicon grease on the internet, had to buy a 30ml tub for 2 tiny finger tips full, but not to worry i may use it again some time . thankyou for all the advice guys appreciated

Hi I am having similar problem with my millennial Europiccolo

I took it my group head apart and replaced the 2 piston gaskets. However, I found something unusual, the bottom part of the teflon sleeve came out with the rubber gasket, it looked like it had broken apart from the top part of the sleeve. I managed to stuff the bottom part of the sleeve back in and reassembled with the piston and the shower screen.

Now I notice a couple of things:

1. The piston is now very very loose when use with no coffee, when doing the pre-flush, it now offers little resistance to pull up and would fall right down with the steamy water if I let the lever go. It used to be very tight and I had to push it down with some effort.

2. When the portafilter is in with coffee, I can pull with familiar but a little less resistance, but it consistently clicks/drops a couple of notches in the middle of a pull, like it was missing a step.

3. The group head now leaks when the water is boiling. It seems to stop/slow down after I let some steam out of the steam wand.

4. Coffee now comes out half decent but lacks body now, somehow all beans similarly mediocre. Crema seems to dissipate quicker than before.

Is the teflon sleeve supposed to be in one or two pieces? Regardless I think I will get it replaced because it looks pretty broken. Also the upper part of the piston seems to be in for good, how do I take it out? Does it screw into the group head?

You are, I think, experiencing the reason why it was a very bad idea for La Pavoni to put polyphenylene sulphide sleeves in these machines. The 1961-1973 models had a somewhat similar design, but with a brass sleeve. I have heard it said that the purpose of the polymer was for insulation, but that does not make sense, the idea is supposed to be that the compression cylinder is surrounded by hot water to maintain a temperature. The glass temperature of this polymer is around 80, if I recall correctly. It is also a crystalline polymer. Polymers tend not to be dimensionally stable, and thermal cycling tends to make matters much worse, and that is exactly what happens in an espresso machine. The same long term dimensional instability also created problems for the pistons.

Perhaps if people complained to La Pavoni they would fix this design and start putting brass sleeves in them instead of this inferior material.

yowser wrote:Is the teflon sleeve supposed to be in one or two pieces?

The plastic sleeve is all one piece, and surprises me that it works at all when broken.

yowser wrote:Also the upper part of the piston seems to be in for good, how do I take it out? Does it screw into the group head?

(assume you mean the upper part of the sleeve) Yes, it's screwed in, the threaded part is close to the bottom with an o-ring providing the watertight seal. You may need to get creative removing it if the bottom has broken off, because that's where you have two slots that let you use a tool to unscrew it. Since you're replacing it you are free to mangle it getting it out.

Thanks homeburrero and rpavlis for confirming my suspicion. It broke relatively clean off and like you I was surprised that it all snapped back together even managing to pull better than Star$ shots.

May I confirm if this is the right part?

This UK shop calls it "Group Internal Piston Sleeve with Gasket"

http://www.espressoservices.co.uk/37113...nal_p.html

The one sold by Orphan Espresso looks slightly different, they call it a "Cylinder Liner"

http://www.orphanespresso.com/La-Pavoni..._2284.html

They look slightly different, are they the same part?

They are the same part. As is this one:
http://espressocare.com/Qstore/Qstore.c...ead+Sleeve

The UK shop sells it with the o-ring included, the other stores sell the o-ring separately. Espressocare also sells a handy little metal bar that fits the slots in the sleeve.

Thanks, somehow espressocare.com is not accessible from my neck of the wood.

Not being handy I think it will be quite a job to pull the upper piece of the sleeve out of the group head. Any creative suggestion welcome.

There was a mention of sort of an adapter to smooth out the penetration of the piston into the sleeve, I never managed to find it from any of the stores, does anyone know where I can find this gadget?

Lovely machine despite all the idiosyncrasy.

yowser wrote:Not being handy I think it will be quite a job to pull the upper piece of the sleeve out of the group head. Any creative suggestion welcome.

Sorry, never did that myself and I'm not coming up with a brilliant idea. Anything that might jam tight inside the cylinder with a handle sticking out that you can get a wrench on, then unscrew counter-clockwise. You may be able to carefully nip some notches in what's left of the bottom to give you something you can drive against with a punch. If it's brittle enough you may be able to nip and chisel it to pieces from the bottom, but if you do that be really careful not to damage the brass that it threads into.

yowser wrote:There was a mention of sort of an adapter to smooth out the penetration of the piston into the sleeve, I never managed to find it from any of the stores, does anyone know where I can find this gadget?

Something like this?
DIY-Olympia Cremina piston rod seal "tool" and Fix
I have never found it necessary on the Pavoni, especially not on the millennium where the bottom of the cylinder is a soft plastic edge. Just take your time and use your fingers or a wood chopstick to tuck the lip of the lower upper gasket inside the cylinder as you gently push on the bottom of the piston.