Fixing Pressure Gauge on La Pavoni Professional

#1: Post by **Escaron** » July 29th, 2021, 6:21 pm

Hi I just recently acquired a 1981 LP Professional v2.2. The machine is in surprisingly good shape except I'm having issues with the pressure gauge. During operation the gauge forms a lot of condensation on the inside to the point you can't even see the dial. I suspect the Bourdon tube has a leak in it and possibly the gauge isn't even reading correctly, it doesn't return to 0 and in regular operation hovers between 1.2-1.4 bar which seems excessive but also possible the pstat is not set properly.

Anyways I'd like to take it apart and look inside and replace the gauge mechanism. Does anyone know how to pull apart this version of the gauge? It is in an all metal case, the screw at the back holds the mechanism to the case but not the case itself together. So far I have not been able to separate the two parts of the case in order to access the dial and mechanism.

Below is a picture of the exact one I have, front and back angles.

Appreciate it if anyone has experience and can advise how to pull apart? I see a bunch of videos online of people just twisting the front off, this does not work for me and I'm afraid of breaking it if I lock it in a vice or something and really start prying it open. I could just get a new gauge but prefer if I can replace only the mechanism inside from a new one and keep the original face + casement as it matches nicely with this machine.

Thanks!

http://www.francescoceccarelli.eu/La_Pa ... C_8465.JPG

http://www.francescoceccarelli.eu/La_Pa ... C_8467.JPG

#2: Post by **Sw1ssdude** » July 30th, 2021, 4:51 am

That gauge body is a simple press fit. you should be able to pry it off, maybe use a little screw driver for persuasion (use the gauge fitting as a lever point, and push the lid off with the side of the screw driver.

after getting the top off, you can unscrew the screws, and slip the bottom case off. now you have the naked mechanism.

you can try setting up a tube for leak testing: add a length of hose to your gauge and a bicycle pump (use your ingenuity...

) and pump it up to 1-2 bar pressure. use enough hose to allow for a bigger body of air, otherwise one pump stroke might kill the poor gauge immediately.

just like here (check post #6 Olympia Express Club rebuild (+ introduction) )

you can also submerge the gauge in clean water for a sec, to check for bubbling, i doubt that this will do harm (if you dry and oil it afterwards).

I doubt that you will find a replacement mechanism (unless you have one already)... if the gauge is statically off-zero, thats one thing, but rebrazing a popped bourdon tube... i dont know, man, seems like a LOT of work...