Hi - I finally got around to rebuild the group head. Everything worked fine until I tried to put the group head screen gasket in place. After the group head gasket is in place I can't get the porta filter into the group any more.

I have bought my pavoni in the UK in 2004. In the UK it is called Professional with a 1.6l tank (I believe it is 16 shots??). Unsure which gasket to buy I bought both for the Europiccola and Millennium and both pose the above problem? I just can't imagine that Pavoni builds different group heads in UK than it does in the US.

What am I missing. Any help or advice would be greatly appreciated!

Did the piston unscrew from the shaft? Sounds like the piston is riding too low in the chamber and the screen is not seating completely.

Usually you have to seat the gasket a little bit before you start installing the portafilter. Also, do you have a round O-ring or a square profile O-ring?

This thread might help also:

La Pavoni O-ring gasket question - wrong size?

Ray

ok - even if this sounds stupid :
once the piston is back in the group there are two gaskets going, right?

so it would be gasket -screen - gasket? This is how I read it from the diagram. I had it disassembled a while ago but thought that how it was. so assuming the above is correct I have:

gasket square - screen - gasket square (I also have a round one and tried that as well)

Cannon - I am not sure I understand - I had everything disassembled and then put together again. when you say low - could you explain to me what you mean?

Thanks so much.

The piston is connected to a shaft that runs out the top of the group. That piston screws onto the long stainless rod. Pavoni's have been knows to unscrew from use. That usually results in no water from the group when you raise the lever but it will also pop out the screen if you pull the lever down with no portafilter in the group. If that piston partially unscrewed it could cause that but the more likely culprit is gaskets. I think the gaskets on my machine were round, not square.

how far down is your piston going before the set nut stops it?
is the sleeve screwed in all the way?

Oliver,

I had to check twice but I believe your problem is the gasket-screen-gasket assembly. Orphan espresso has an excellent two part video on a Pavoni rebuild and in the second video Doug shows and says there is only one gasket on the outside of the screen. It's been a while since I rebuilt my milleneum Romantica but I am sure there is only one gasket, not sure if it is round or square but the one Doug puts on looks to be round.

Bill

I am sure there is only one gasket, not sure if it is round or square but the one Doug puts on looks to be round.

actually for millennium groups the original pavoni gasket is square on one side
doesn't mean it will not work if you have an aftermarket one but it could be the issue itself

oliverkuehberger wrote:ok - even if this sounds stupid :
once the piston is back in the group there are two gaskets going, right?

so it would be gasket -screen - gasket? This is how I read it from the diagram. I had it disassembled a while ago but thought that how it was. so assuming the above is correct I have:

gasket square - screen - gasket square (I also have a round one and tried that as well)

Cannon - I am not sure I understand - I had everything disassembled and then put together again. when you say low - could you explain to me what you mean?

Thanks so much.

There's only 1 O-ring involved on the dispersion screen. Install the O-ring onto the screen (as shown in the link above), then press the screen/gasket into the group head. The O-ring holds the screen in place. When you first insert it, you'll probably need to press the O-ring into the grove in the group head a bit, before you can insert the portafilter. Once you can get the portafilter to engage, then you can use it to sort of seat everything down.

Keep in mind, you'll also need to set how far down the piston rod can travel (using the two nuts), such that (at the bottom of the stroke), the group head piston does not dislodge the screen out of the group head. Basically, once the dispersion screen and gasket are in place, you can push down on the lever and feel it start to pop the screen back out.

Ray

Thanks guys - I appreciate the help. I suspected that I might have read the diagram wrong. Now I have put everything together but fear that i will have to disassemble again tonight.
When i pulled my first shot, there was literally no resistance and coffee came right through the portafilter without even pulling down. So I wanted to see whether you agree what i might have done wrong:

When I changed the gasket on the piston and put them back into the group I had a hard time getting it in. so I used my leatherhead (forgot what piece) to get push the first gasket in. consequently the V-shaped gasket is not "going against the grain". Do i make sense? I suspect that the v shaped gasket actual needs to almost flop "open". I know I have a hard time explaining but it's the only thing I can think of.

Any opinions would be great appreciated!

Thanks!