A brief commentary on the strip down and rebuild of my La Pavoni PUB circa 1988
I bought the PUB from an online auction, the seller advertised it as "works well" noting the only fault as a dripping steam wand and some cosmetic damage – well, it worked but only just. Obviously well used and fairly grungy but performed all the necessary functions required of an espresso machine.
I gave it a quick check out so I could determine what needed doing to get it in good working order. I stuck the input hose in a bucket of water and carefully switched on. It slowly came up to pressure (10-15 mins) with a few creaks, groans and wheezes. I noticed some occasional drips from the steam wand and also from the group, there was a leak from the top of the water level glass. The pstat was set way too high but after adjusting I had it cutting out at 1.2 bar, it came on again at about .95 - a dead zone of .25 is a bit on the high side. Tested steam and hot water, both seemed fine, auto fill worked ok. Hit the brew switch, pump fine, water out of group ok if a little slow.
On this basis I decided not to do a full strip but just fix the leaks, kit the pstat and descale without removing the boiler. However as I started working on it, more and more pieces came off and I eventually ended up pulling out everything except the pump and wiring harness!
It’s a very straight-forward machine to work on, only electronics being the black-box for autofill. Strip down was pretty simple, removed all panels, steam and hot water valves, solenoids and the copper pipes till the group and the boiler could be removed. Build up of scale had the effect of locking the joints so most of them needed some encouragement (some a lot) to come apart by tapping the spanner firmly with a hammer.
A Pavoni PUB kitset!
The pic above shows all the parts ready for assembly. At this point I had stripped and rebuilt all the individual parts including steam and hot water valves, group, pstat and boiler. All necessary parts were obtained from Coffeeparts in Sydney, cost me around NZ$150. These are the main parts I replaced -
The group was completely gunged up, gasket was rock hard. I had to chip it out mm by mm which took nearly an hour. After soaking in Purocafe and then citric acid, it came up well. Normally you would remove the heater to gain access for descaling but I didn't have a spanner big enough. I removed the other fittings from the boiler, filled it with citric acid solution and let it soak for 24 hours. Having done this 3 times it was completely free of scale, did the same for the heat exchanger. All fittings and copper pipes were soaked in citric acid and scale removed.
When I put back all the brass fittings in the boiler I used Teflon tape on all joints that didn't already have a Teflon seal. Wasn't sure if this was appropriate but none of them have leaked since.
OK, major parts back in and ready to be hooked up.
And ready to be tested out (you can see from the gauge she is actually up to temp here).
I left the heater disconnected, put the input hose in a bucket of water, switched on and stood back. She (yup, I’m sure it’s a she) started autofilling but I found I had a leaky fill solenoid so switched off, reseated the solenoid and all was ok. Once it was full I connected the heater and waited for it to heat up. This went well, no creaks or groans as before, however as it came up to temp the safety valve started letting off steam. Stopped again, removed it and reseated brass fitting where it seals on the teflon plunger by turning it on some 400 wet and dry paper till the mating surface was nice and shiny. Refitted, turned on and it came up to temp no problem. I checked the pump pressure using a pressure gauge attached to the PF, got 8 bar, once it was plumbed in I got 8.8bar - didn't see any need to adjust it. The heater was cycling 18 seconds on, 100 seconds off from .95 to 1.15 bar.
Have had it running for a while now, making great espresso from the first shot. Its a thermo-siphon but the design is such that the group does not seem to overheat too much after being idle. However being an HX machine you need to remember to do a 10 sec or so "HX flush" if it’s been idle for a while. Reasonably good steam given the pstat is set fairly low tho you can catch up with the heater if you do successive lots of steaming. In short she’s a beauty mate!
Forgot to mention I re-sprayed the side panels and front plastic "cheeks".
My shiny PUB with her little friend.