Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 27

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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drgary
Team HB

#261: Post by drgary »

I just polished out what I could on the heating element, which previously tested as working. This close-up doesn't quite capture that there's still a small amount of rust I can't reach where the contact tabs wrap around the end posts. I wonder how or whether to treat that tiny amount of rust because it can continue oxidizing over time. I would use something like Naval Jelly but that needs to be rinsed off with water. Before installation I'll coat the contacts with glyptal to make sure they stay sealed. Where the element inserts in the boiler plate was previously wrapped with PTFE tape, and I'll wrap that again.

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The manufacturing date (1/1978), wattage and voltage are stamped on the element.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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TomC
Team HB

#262: Post by TomC »

Wow, that element is older than me by a couple months :)

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orphanespresso

#263: Post by orphanespresso »

Nix the naval jelly....abrasive blast the rust...no water needed. And that ptfe tape..double nix...use the right silicone o ring or alimentary gasket!! The ptfe was done aftermarket so to speak.

You sure are moving right along on that Prestina!! :wink:

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drgary
Team HB

#264: Post by drgary »

You challenged me to take this on, Doug. Thanks for the encouragement, I guess! :lol:

There's a zen to this, looking over each part and deciding what to do. Should I measure the parts and have you gather together some gaskets and such of the right sizes? Since I don't have a media blaster, should I send you the heating element for that?
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#265: Post by RayJohns »

Soda blaster... that should do the trick :-)

Ray

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doubleOsoul
Supporter ♡

#266: Post by doubleOsoul »

Can't wait to see it next week Gary!

negrocorto

#267: Post by negrocorto »

I'm wanting to tear into my Prestina, but am lacking a couple of washers/gaskets, and can't find them. The issue is finding a washer/gasket that goes where the steam wand and hot water spout attach to the boiler. Do any of you know where I can find some, whether original or not? Or know how to resolve this issue otherwise? The end of the steam wand has the shape somewhat of a half bulb, that allows for the wand to move around. The washer that was there originally looked like it was silicon and conical, and this allowed the wand to swivel back and forth.

Thanks,

Albert

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drgary
Team HB

#268: Post by drgary »

Alberto:

Two places to find washers and gaskets are Orphan Espresso and Allann Brothers. Those are my current sources, and since I just talked to one of them the other day ...

Doug suggested I can use a rotary tool with a wire brush to deal with the rust when I pushed back on cluttering my garage with a media blaster I'd seldom use. I've made progress on the heating element today and on the water and steam valves. First the heating element.

I cleaned off most of the rust as Doug suggested. He didn't seem concerned about runaway rust on this part.

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Then I picked out what seemed like soft silicone sealant.

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I thought it might be a good idea to seal the ends using the Orphan Espresso heating element repair and sealing kit. I started by mixing the epoxy, rolling it and molding it on.

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Then I realized it was sticking out at least even with the threads so it could impede fastening down the element with a nut. I looked also at the metal casing around the contact. With the Orphan Espresso kit, you put on epoxy, then a casing like that around it before sealing it all in glyptal. If this is the casing it probably doesn't need re-sealing, especially since the element tested fine again today with my multimeter. So I removed the epoxy. Now the trick is for this first-timer to determine how to fasten that element in a way that's waterproof under pressure. Looking closely at the element end it appears there's also PTFE (Teflon) baked onto the flange where it fits inside the boiler entry hole.

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Here I've found the nuts that I'll also clean up. But I'm wondering whether instead of using the Orphan Espresso kit I can get them to recommend a high-temperature silicone for sealing and whether I should do something like wrap Teflon tape around the flange. Here's the heating element fitted into the boiler plate, outside and inside. I'll await expert advice to do this right.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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drgary
Team HB

#269: Post by drgary »

Today I also figured out the valve bodies for the steam and water taps. I thought I was dealing with a screw holding in place some brass washers and rubber gaskets. The knob fits on the shaft to the right. Presumably the head of the screw is on the left end.

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But when I wiped off the end there was no screw slot. How could I get this apart?

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If you look at the first picture, notice there's a slot in the middle. Also, oddly, it's not solid straight from end to shaft. The next photo shows there's a tiny hole in the bottom brass piece on the bottom. I puzzled over this for awhile. This is a small part and wasn't as visible to me as these close-up photos. I probed the grease-filled slot with a picking tool and discovered a c-clip that removed easily.

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Now the valve body came apart in halves.

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But I was still mystified at how to unscrew the brass washers from the rubber gaskets. I wondered if I should put this in a vise and grab the pick hole to turn it. Before doing that I inserted the pick into the hole and couldn't see it easily moving. Then I probed one of the gaskets and discovered this is like a miniature of a lever machine piston. The gaskets insert in grooves on a machined piece of brass. I'm still puzzled by the piece on the end, which seems to be hard plastic, and can't tell how to take it off, so I won't! Except ... I've just noticed when posting this that there's a tiny pick hole in the groove where this piston inserts in the slot. Maybe grabbing that and the hole on the other end would allow this thing to twist apart even further. No matter. I'll leave it in place and hope the two rubber gaskets are enough to create a good seal.

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There was still something in the gunked up slot, a ring when I looked sideways. Probing from the end my pick revealed a brass spacer that inserts there.

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Being new to this I had to puzzle, how do I clean it? Coleman gas? I'll then have to work hard to clean that off. Then I remembered I've got a degreaser made from orange oil.

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All those greasy parts went into a little canning jar for a citrus bath.

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Taking this apart was a rewarding piece of detective work. It probably took twice as long to puzzle it out as to do the disassembly. Now I truly know how this piece works, and I guess it's going to go that way as I put Humpty Dumpty back together!
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

negrocorto

#270: Post by negrocorto »

Thanks Gary. I'm currently discussing this with Allann Bros. Just need to send him photo of the wands for reference.

Albert