La Pavoni Shower Screen Popping Off

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chrisargar
Posts: 7
Joined: 2 months ago

#1: Post by chrisargar »

Hey all,

After a few years of faithful service, my millenium Professional's shower screen o-ring partially slipped out of the seating while flushing one day. I took the hint do to some long overdue maintenace and did a full teardown, clean, and seal swap. I would've said this was an easy process until this morning when I went to flush the screen and my brand new o-ring and the shower screen came out with a large pop and accompanying spray of hot water everywhere.

After following previous advice from this forum, I already checked the following:
- the o-ring is installed round side up, flat side down
- the piston isn't pressing on the screen. The dislodge occurs when the lever is raised, and the piston is sitting as high as possible (definitely overtightened here but I wanted to eliminate this factor)
- I washed off all the 111 I applied to the o-ring and used a q-tip to try to clean the o-ring's housing (I mistakingly assumed ALL o-rings needed to be lubed...)
- I seated and reseated the screen and o-ring a hundred times with the stock portafilter

The machine can still technically make coffee because everything stays in place while the portafilter is installed. But I'm at my wit's end and about to just order a new o-ring. Am I missing anything here? Any help at all is appreciated.

Thanks!

jtrops
Posts: 499
Joined: 9 years ago

#2: Post by jtrops »

I don't think wiping it off is good enough to clean silicone grease from the surfaces. You may try using detergent to clean it, but silicone is pretty hard to get rid of. Still you may get enough to keep the portafilter gasket from popping out.

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guijan12
Posts: 588
Joined: 6 years ago

#3: Post by guijan12 »

Welcome Chris!
Despite having dismantled my LPP grouphead for probably 30 times or so, in the pervious years, I have never had the showerscreen pop out, with the piston up.

I always lube the o-rings, including the showerscreen o-ring.

I can think of 2 reasons why it pops out;
  • The piston presses it out, when at lowest point (raise the piston with the nuts on top, so that it rests, slightly above the screen), or
  • The showerscreen was distorted, while disassembling (replace)
I hope this helps, maybe others see more possibilities to help. :lol:
Pictures may be helpful, to determine what is wrong. :idea:
Regards,

Guido

jtrops
Posts: 499
Joined: 9 years ago

#4: Post by jtrops »

I second guijan12. I also lube my PF gasket without it coming out. It's a very thin coat, but it's there.

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chrisargar (original poster)
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Joined: 2 months ago

#5: Post by chrisargar (original poster) »

Thanks for the quick responses. Here are some images and a (kind of funny) video of the problem.


This is the piston with the lever fully down. Hopefully from this picture you can tell that the piston is set quite high; the shower screen looks like it only contacts the piston chamber, never the piston itself.


The screen doesn't appear warped to my eyes. Going off of the video, it think the o-ring is failing, though there's no visible damage to it. Maybe I just got a bad o-ring?

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ei8htohms
Posts: 141
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#6: Post by ei8htohms »

Could it be that the piston sleeve is not fully inserted/tightened? You'd think that something like that would prohibit you from properly securing the portafilter too, but this seems pretty mysterious.
LMWDP #751

jtrops
Posts: 499
Joined: 9 years ago

#7: Post by jtrops »

First of all, set your piston lower. It should be just barely above the shower screen at the end of the travel.

Second, try doing your flushes with the PF in place for awhile. I'd bet that after a few cycles it will stay put without the PF. You may want to try cleaning the o ring and shower screen with dish detergent to get more of the silicone off.

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chrisargar (original poster)
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#8: Post by chrisargar (original poster) »

ei8htohms wrote:Could it be that the piston sleeve is not fully inserted/tightened? You'd think that something like that would prohibit you from properly securing the portafilter too, but this seems pretty mysterious.
I didn't touch the sleeve during cleaning except a wipe down and some light lubing so I don't think so. As you said it would probably be obvious if it was loose.
jtrops wrote:First of all, set your piston lower. It should be just barely above the shower screen at the end of the travel.

Second, try doing your flushes with the PF in place for awhile. I'd bet that after a few cycles it will stay put without the PF. You may want to try cleaning the o ring and shower screen with dish detergent to get more of the silicone off.
I've lowered the piston. It was only set that high because I knew it was the first thing people would ask.

I'm away for the next few days but I'll give everything another wash and try flushing for a while with the PF in place when I'm back. Maybe thermal expansion will take care of it.

Thanks for the help, I'll report back soon.

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chrisargar (original poster)
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#9: Post by chrisargar (original poster) »

I'm back and happy to report after several days of flushing with the stock PF tightly inserted, the shower screen appears to be staying put during regular flushing. I guess the most likely culprit was over-application of 111 to the gasket but I can't say for sure as I was trying multiple fixes at once.

Thanks to this great community for the help, especially jtrops. Hopefully that's the end of this misadventure.

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guijan12
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#10: Post by guijan12 »

Nice to hear!
Enjoy your espresso's. :!:
Regards,

Guido