Pre-M Pavoni Upper Group C-clip

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SpromoSapiens
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#1: Post by SpromoSapiens »

Got an early 80's Pav here. Cleaning it up, replacing the seals; as you can see, the upper group C clip is rusted & broken, but it's still in there, still apparently keeping the washer & mini-o-ring in there. I'll replace it eventually, but what exactly is the function of this little assembly? For now i'm thinking that if it stays put while i clean & reseal everything else, and there's no monster leak from the area, i'll leave it until a replacement arrives. How important is this little trio to overall function?

DanoM
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#2: Post by DanoM »

That clip keeps the "washer" with holes in it in place to keep the piston rod seal in place. It's important to the operation of course and to keep steam from coming through that area when the piston is all the way down.

You'll want to replace it with a stainless keeper ring, or at least something that isn't going to corrode, as that area is wet all the time. My La Pavoni came with a regular steel ring in there that had completely rusted over and I thought it was some kind of coffee crud instead of metal. After 1 hour of picking it out I finally had everything clean, ordered the proper parts and haven't had any rust issues there.

I sourced my replacements through Orphan Espresso, although they are likely available elsewhere too.
LMWDP #445

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stefano65
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#3: Post by stefano65 »

Remove it using a pick
replace gasket (p-49) and replace clip as well
Stefano Cremonesi
Stefano's Espresso Care
Repairs & sales from Oregon.

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civ
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#4: Post by civ »

Hello:

You are looking for a Internal Type HO Retaining Ring.

I don't have my box of spares at hand so I am not able to give you the size although I have a faint idea that it could be 7/8". But I suggest you measure the broken one once you get it out.

As it is not mounted on a shaft, you'll only need measure two things: thickness (T) and free diametre (F).
It's best if you use a caliper.

ImageImage
Drawings courtesy of American Fastener Technologies Corp.

I expect that Grainger has the one you need:
http://www.grainger.com/search?searchQu ... +stainless

For example, the 7/8" one in stainless comes in bags of 5 and costs USD 13,14.
See here to check the 7/8" ring's dimensions:
http://www.grainger.com/product/Retain- ... s_pp=false

Cheers,

CIV

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hankbates
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#5: Post by hankbates »

I would be worried that if the clip moves out of its groove into the shaft (there is no tension holding it in place) it could score the piston shaft. This would require that the shaft be replaced.

Best to replace promptly.
Some people rescue dogs and cats, I like to rescue Livias…

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SpromoSapiens (original poster)
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#6: Post by SpromoSapiens (original poster) »

Dang it, I thought I was close to getting this thing up on the counter already. If you think it's a hazard, Richard, I'll wait for the part to come in. Thanks for the tip. And thanks Dan for the info.

Carlos -- Thanks! Very helpful info, but as I don't have calipers I'm probably just going to order the part from espressoparts.com.

Stefano -- thanks to you too; I checked your site but didn't see the part listed solo (not trying to turn this into an inquiry; just excusing my ordering elsewhere).

I just received the Pre-M EuroP Full Rebuild gasket set from OE, and I believe that it came with an upper group gasket, but I'm actually having a hard time figuring out what goes where. Last I check the set was out of stock so the description is down... The set does include this gasket, right? Is this it?

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grog
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#7: Post by grog »

That is the piston rod seal that goes under the washer and c clip.
LMWDP #514

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

Excellent. Thanks greg. I guess waiting for the c-clip to arrive will give me time to scrub this sucker. Let's say i do a vinegar descale of the boiler, bringing it up to temp but never lifting the lever... if i dont open the path to the group, is there any danger regarding this clip vs. the piston?

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hankbates
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#9: Post by hankbates »

There would be no risk at all if you do not allow the boiler to build pressure. That is, other than the normal slight risk whenever you use an acid cleaner to remove scale, which also removes the protective oxide coating from the surface of the copper.
Some people rescue dogs and cats, I like to rescue Livias…

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stefano65
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#10: Post by stefano65 »

Thanks for checking on our web page,
I actually buy them from different source then the pavoni importer
and the one we sell separately from the kit are (kit comes directly from importer)
however the one that come in the kit might be different material from years ago
since now days you barely see one rusting, like some old one,
or perhaps is just a question of HOW long the piston has been leaking,

"Stainless steel rings made of DIN 1.4122 stainless steel, which has similar properties to 400 series and is magnetic."
I will add them on the part listing sometimes today as separate item from the kit
Stefano Cremonesi
Stefano's Espresso Care
Repairs & sales from Oregon.

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