I have a 6-month old La Pavoni Pro, which has worked perfectly... up until last week. When i turn it on, as the water heats up, rather than building up pressure, it instead just releases all the steam out of the safety valve thing on the side... as a result i have no pressure. I've watched it doing it, assuming it will stop after a while, but it literally goes through an entire boiler of water, and sends it all up the wall as steam.

Absolutely nothing has changed that i am aware of that would explain this sudden behaviour.

Has anyone else experienced this problem or know how to solve it? It's driving me nuts.

Just a guess but it sounds as if the valve is stuck open. Have you tried giving it a whack with the portafilter as it is starting to steam. I some times have it stick and after a sharp rap it closes up.

Why may take a little disassemble. Something (scale?) got under the seat.

Bill

A machine of that age should not be doing that at all. It's a very easy part to service.

Get an angled box wrench (I forget the size. 16mm?) They're pretty common, one end is open, the other box (closed) angled a few degrees. use that to hold the nut inside the boiler. You can then slip a socket wrench over the nut on the outside of the boiler and take the whole thing apart. It really helps to have a 16mm wrench to get to the second bolt that is right next to the outside of the boiler, but it's not absolutely critical to the repair.

Anyways, once you get it apart clean it with some descaler and reassemble.