Bluecold wrote:http://www.hitechseals.com/chemical-compatibility.asp?chemical_id=1504

This is a massively useful link.
H/T to gamgra

thanks...goto get with it

AndrewYabsley wrote:For a long time after pulling the lever up or down an extremely fine black graphite-like residue would be left on the each side of the top of the portafilter. What the hell was that ? I must be crazy.

I think it is finely corroded metal from parts (although well lubed) sliding against one another. Maybe it is dust that catches in the lube. I gradually get a bit of a built up as well where the top of the shaft slides up.

Did you have to remove the group from the boiler and then disassemble the group to get at the gasket ?

My machine is a little earlier generation than yours. Single switch but the portafilter is the smaller one with the group in brass instead of brass with plastic liner. I borrowed a friends Millenium LP (like yours) and found it quite easy to disassemble as mine is. Removing the shower screen is sometimes a bit tricky as the seal around it holds it in place pretty well. Once that is off, the lever allows you to push the piston down then remove the C clamp and rod so that with a little pressure on the top of the piston shaft, the piston will come out of the group. Replacing the piston is just the reverse. Maybe that plastic liner is an additional reason to choose the lube carefully , I don't know but Dow 111 is a good choice. But I can disassemble the group/piston without removing it from its position bolted to the boiler.

There are a number of good threads about the pavoni. Pavoni Express was a very useful website that was closed at the end of 2010. Good thing I archived all that information on my hard drive.

the reason why I was asking if yours has a sleeve or not
is because sleeves
gum up from coffee residues and will make ALSO make a lot of resistance on the piston
eventually sleeve will also warp and crack,
so from the all good point from previous reply look at the sleeve as well

Chert wrote:I think it is finely corroded metal from parts (although well lubed) sliding against one another. Maybe it is dust that catches in the lube. I gradually get a bit of a built up as well where the top of the shaft slides up.

hmm. strange though as it seems to arrive out of the shaft when I raise the lever. It could be as you said. I make/repair surgical instruments for a living and so have lots of hands on experience with metals && plastics and so I am not sure this is the source of the black residue... seems like it might have come from the lower pin in the lever handle ....but I know this .. once the back powder stopped coming out the machine stiffened right up. Coincidence perhaps.

The info you provided regarding taking apart the group was awesome ! Truly all I needed was a little info from someone who knows this machine and has had it apart .. u sound like an experienced home espresso man for sure. Anyone fixing their own machine is on the ball.

I LOVE my machine ... that said however ... mine was a gift from my Dad who fixed his old world machine ( we machined the missing parts in my shop ) My millennium machine has that nasty gold coating that was done very poorly from the factory. The coating on the inside of the sight glass is peeling off and the outside of the machine in terms of quality of craftsmanship is not the best.


No matter I love the coffer it makes and thats all really counts to me.

I have seen the 'parts kit for new group' pavoni machines out there in the UK and also found Espressoparts.com which has a great blow up diagram of parts for sale , really good. SO I 'l get some stuff and replace the boiler gasket and then do the group.

Again many thanks I'm sure you'll be hearing from me again before this is over.

stefano65 wrote:the reason why I was asking if yours has a sleeve or not
is because sleeves
gum up from coffee residues and will make ALSO make a lot of resistance on the piston
eventually sleeve will also warp and crack,
so from the all good point from previous reply look at the sleeve as well

sleeve ? since mine is a millennium machine I guess it does ... now to see about the sleeve. Thanks very much for those comments Stefano. Something has been wrong with the resistance in the piston/shaft on this machine from the start.

Is this the same machine?

http://www.espressoparts.com/LaPavoniEu...alDiagram2

If so, for water to be coming out the shaft it has to be getting past the upper piston seal and then on the upstroke it is forced past the shaft seal.

Thanks to espresso parts for the diagram and info.

Good luck
Geoffrey