Refeathering the Peacock - Pavoni head gasket replacement - Page 3

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

#21: Post by mhoy »

homeburrero wrote:Mark:
Check out this post (from Doug at OE) : If Levers could talk - about dealing with a frozen lever rod pin.
Thanks it's kinda what I was thinking, but got worried that it was threaded or some crazy thing. It's soaking in oil for the night. See what it's like in the morning. I'd like to be able to take the soft wheeled bench wheels to polishing it up to make it look as good as new. Well sort of, there are a couple of dints in the nut that hold the piston in place. Not sure I'll do the sight glass as the seal is currently water proof and I don't want to break the glass. There is virtually no scale in the boiler so it's a pretty easy job. Lots of gunk under the shower screen though. I'll give them some Joe Glow along with usage instructions to keep it in better shape. :D

Mark

Flasherly

#22: Post by Flasherly »

In the picture of the piston w/ newly assembled rings. . .the V-s "... Always point away from center."

The whole of the ring cross section is V-shaped. For then, at the final picture, were it (mis)understood as put together backwards with the V-s pointing towards one another. What is not implicitly stated is the "V-s" are inside the ring formation, on opposite sides of its diameter, for a concave die cast comprising, distended to one edge for a outwardly whole, inverted-V appearance, whereupon the opposite side to the flange is simply flat.

I happen to like better a description I was given with the purchase: [The only. . .] flat sides to the ring face one another when placed on the piston.

Splitting words, know I, although at times I've that tendency to do very things those the way intended god.

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mhoy

#23: Post by mhoy »

Tapped on each side of the pin until it started moving, added more oil, voila out it came. My next question is should there be significant grooves in the pins? Or are they considered 'replaceable' wear items? I've no idea how long they have used the machine, I'll have to ask.

Mark

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mhoy

#24: Post by mhoy »

Looked up new pins on line, yep, no grooves other than the end for the clips. So these are really worn down. Have to order a new set for it.

Mark

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drgary
Team HB

#25: Post by drgary »

srobinson wrote:With the group head now off, it is time to remove the plunger and the group head screen. Please note...DO NOT USE A SCREWDRIVER! Damage can occur. The best way to do this is to invert the group head and carefully press the threaded stem until the basket breaks free of the group head gasket.
I agree that you don't want to use a screwdriver here. But when I tried to "carefully press" to free up the portafilter gasket and screen, it wasn't yielding. Fortunately on one of those days when I visited Christopher Cara, I saw him servicing a grouphead as his father had taught him to do. He removes the dipper tube and then mounts the grouphead upside down on the machine like this. The rest is my improvisation. I used a picking tool to remove the portafilter gasket and shower screen. Both came out easily without damaging anything.



Then I removed the grouphead from the machine, pressed the top of the piston shaft onto the wooden workbench, and it came out easily. Removing the dipper tube isn't hard. It's threaded and turns out counterclockwise.



Removing the piston gaskets from the brass piston is easy using the picking tool, something I've also seen Christopher do with very old, stiff gaskets.

I'd recently acquired this machine and knew it was time to service the group when it would dribble on warm-up. But I was confused by the "lever erectus" where the lever raises as the machine cools, suggesting a tight seal in the piston gaskets. Someone on another thread had suggested there were coffee grinds interfering with an otherwise tight seal, but that wasn't the case. So the gaskets were past their prime and would create a tight seal only when heated.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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TomC
Team HB

#26: Post by TomC »

I'll be following this thread step by step sometime in the next week for my Pav's. Very helpful.

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mhoy

#27: Post by mhoy »

Two very good videos from OE on it too:
Mark

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drgary
Team HB

#28: Post by drgary »

srobinson wrote:The first parts to replace are the upper seal and brass retainer ring in the group head.

<image>

Special tool needed here are spring clip pliers, but they are readily available at any auto parts store or at Sears. A great diagram from The Unofficial Pavoni Page that shows how these three parts go together

<image>

(Image courtesy of David Jenkins)
"The times, they are a changin'."

That web site is no longer up, so there's no diagram. Added later: Here's Francesco Ceccarelli's page on changing the gaskets.

So, folks, I serviced my 1990s pre-Millennium Pavoni this weekend, fired it up today and it still had a nose drip afterward when heating up. Following the Orphan Espresso instructions, I inserted the white gasket with the groove facing downward. I don't think that would cause the nose drip, though. I did install the gaskets with "V's" (grooves) facing outward, so what might I be missing here that there's still a group head leak? The only thing I can think of is I may not have smeared as much Dow111 on there as was called for, especially on the metal ridge between the piston gaskets. Any ideas?

Added later: This post lingered for about a week with no response, so I've started a new thread here. I'd changed out everything correctly but the piston gaskets didn't quite provide a good seal. With the help of other H-B members I decided to use Teflon tape as a shim to make those gaskets stick out more and the problem is solved.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!