La Peppina dripping group

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grog
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Postby grog » Aug 02, 2017, 3:58 pm

Just rebuilt a Peppina (a 1976 based on the date stamp on the bottom). Fired it up to pull a shot, and after removing the PF, the group dripped steadily. I put a container under it and observed for a few minutes, until it became apparent that the drip wasn't going to stop until the boiler was emptied.

I'm a fan of the search function and have read through several Peppina threads, including the 'Peppina Redux' mega-thread. Nothing about this issue. I suspect this is the small flat washer, not properly seating and sealing, and allowing water to continue through the group. Before I take it all back apart, any thoughts on which way it might need to be adjusted? OE and others note tightening the screw that holds the washer in place just until it it is tight and the washer is still flat, not cupped. So I am not sure if I have overtightened or undertightened. I could see either one being problematic. Over, and the washer is cupped and cannot seal completely due to the outer edges always being pulled away by the center. Too little, and it never would sit flush to seal.

But it isn't a very complicated thing, and when I rebuilt a Comocafe (same system), the fine tuning was with the group gasket, not the flapper washers. Could something else be causing the drip? Or perhaps the washer isn't pliant enough?

I hope this isn't potentially the larger flapper washer, since that would mean removing the kettle again. I guess that could also be mis-adjusted as above, allowing water through the cylinder past the piston and into the group.
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yakster
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Postby yakster » Aug 02, 2017, 7:27 pm

It sounds like you have a good understanding of it, that over-tightening the group flapper washer can cup it potentially causing it to leak. One trick you didn't mention is flipping the flapper if it's cupped downward so that the washer cups upward. Last time I tuned my La Peppina, I played with the tightness of the flapper and pumped the lever to optimize the spray pattern out of the washer.

Since this is a gravity fed group, both washers would have to be leaking for a constant drip. When I'm priming a dry La Peppina, the water doesn't draw well presumably because the washers have been dry so long so I take the screw off the front of the group and squirt water in there to help prime the flapper washer system. Doing hard pumps seems to re-seat the flapper washers and get things working well.

What if you took the front screw off the group, took off the group flapper washer and held your finger and found some way to force water or air pressure back through the system to help seat the flapper washer under the kettle? Back pressure would force that washer closed and you could see if it's closing all the way or not, this might help prevent having to remove the kettle base to get at the washer, but I'm not sure that this will really work.

Good luck, let us know how it turns out.
-Chris

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grog
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Postby grog » Aug 02, 2017, 8:01 pm

It's the one failure of an otherwise ingenious system - there are multiple variables that are a bit more difficult to isolate than with other groups. I guess I'll start with the path of least resistance and see if slightly loosening the small group washer helps.
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yakster
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Postby yakster » Aug 02, 2017, 8:16 pm

With everything assembled, removing the front group screw and applying positive pressure into the group should close both flapper washers and result in a sealed system. This might be helpful as a test and maybe even as a way to help seat the washers better, or I could be dreaming.

I just realized that this is incorrect, the flapper washer below the kettle will be sealed but the flapper washer in the group will open with this pressure.
-Chris

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grog
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Postby grog » Aug 03, 2017, 1:23 am

Took the group apart, and thought I had isolated the drip to one of the dispersion screen screws. It had some scale that was making that screw a bit more difficult to get in. Cleaned it out, reassembled, still no joy - slow drip. I should note it only drips once I pull the lever. A full kettle doesn't drip if I've not engaged the lever.

So I took the group apart again and tightened the flapper washer a bit more. This noticeably increased resistance on the lever - as in, the lever return rate slowed down considerably.

But it still drips. I'm guessing I either didn't tighten the large flapper washer adequately or perhaps need to go ham on the Dow 111 in the cylinder. So off the kettle will go tomorrow,
I'll lube the piston and cylinder a bit more, crank down the large washer a bit more...and cross my fingers.
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grog
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Postby grog » Aug 03, 2017, 11:15 am

Francesco advises that this is indeed an issue with the large washer being insufficiently tightened. He also noted that one can shim the piston face with aluminum tape if the problem persists.
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redbone
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Postby redbone » Aug 03, 2017, 11:22 am

grog wrote:Francesco advises that this is indeed an issue with the large washer being insufficiently tightened. He also noted that one can shim the piston face with aluminum tape if the problem persists.


Great info, good to know. Thanks for sharing.
ON A QUEST FOR BETTER ESPRESSO


Rob
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grog
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Postby grog » Aug 03, 2017, 3:46 pm

The more I thought about it, I knew deep down it had to be that the piston was allowing water past from the boiler. Once lever is engaged, an insufficiently tightened large washer won't re-seat adequately to stop water flow out of the now-flooded cylinder. But a new kettle that never had the lever engaged just allows the water to sit above that cylinder, so the piston o-ring is sealing it. I just really didn't want to remove the kettle again, but I suspect it will be much easier now that it has come off just a couple of days prior and is freshly lubed. I am 99.9% certain the brittle seals I removed were the originals and it likely had never been lubed after factory install in 1976.
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UFGators
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Postby UFGators » Aug 04, 2017, 5:13 am

grog wrote:The more I thought about it, I knew deep down it had to be that the piston was allowing water past from the boiler. Once lever is engaged, an insufficiently tightened large washer won't re-seat adequately to stop water flow out of the now-flooded cylinder. But a new kettle that never had the lever engaged just allows the water to sit above that cylinder, so the piston o-ring is sealing it. I just really didn't want to remove the kettle again, but I suspect it will be much easier now that it has come off just a couple of days prior and is freshly lubed. I am 99.9% certain the brittle seals I removed were the originals and it likely had never been lubed after factory install in 1976.


What type of gasket do you have? The large circular flapper one.. Is it OE, Francesco, OEM? I have worked with them all and they all have their quirks. The biggest reason you get leaking is due to over tightening the single screw that holds it into place. The next thing it could be is that the disc is installed upside down. If you look at the gasket, one side is very so slightly curved in one direction. The curved part must face up against the metal. Feel free to contact me directly if you want more help, I have built about 6 of these and I have a good handle on the headaches that took me hours but now I can fix in minutes.

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grog
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Postby grog » Aug 04, 2017, 11:56 am

I've got a NOS OEM set from Deluxe Coffee. I think I have it all set now. Removed the kettle, tightened the large flapper washer a bit - it is in fact slightly cupped - and re-assembled. At first it was still dripping and I thought I was in for a more involved trouble shoot, but then I noticed the kettle was about 2mm from being fully seated in the cylinder. Backed out the set screw, removed the back bolt, tapped the screwdriver back in and got it fully seated. No drip at all now.

It's interesting that the brass screw that goes into the large washer has a ridge under the head, such that you can't make it flush to the washer. This puzzled me but I can only assume it's by design, although I can't ascertain the purpose.

Now I'm working on dialing in dose and grind. I have had a Peppina and Comocafe in the past and forgot that they are a bit finicky that way. So far it seems to take a coarser grind than I had recalled.
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