Ok, folks, I'd appreciate some help on this one-

It is well and truly jammed. This happened while making a shot... the lever went down without building pressure, I yanked it up in frustration, and it got stuck more or less as you see below... although I did 'assist' it a bit with a piece of wood and a mallet... something that worked the last time this happened!

Plenty of verbiage available on request.




Please excuse the crappy pics!

BTW, I've got another Caravel (yellow, sans PF) on the way from Italy as we speak

Regards, Henry

Good news about the yellow one on the way! I think I saw it. Looked lovely.

Anyway, back to the stuck piston. I can't quite make out where the circlip is in all that. Would it be possible to compress it with circlip pliers and then ease it downwards so you can pull the piston out?

easier to remove from below? otherwise looks bad. That piston seems to be from the last type of caravel and is weaker looking design than all the earlier ones.

Looks like you may have a new handle for that yellow machine... sorry I can't help - looks like a chinese puzzle of fiendish proportions. I have plenty of machines on my bench with issues as hairy...

Maybe you could use temperature. This is all just off the top of my not so mechanically inclined head. Freeze the whole thing. Then try heating just the cylinder to expand it enough to let the piston loose? Maybe?

It looks like the piston is locked into the groove in the cylinder at both the top and bottom. I can't imagine a worse way to get it stuck.

With the normal caveats of risk of damage to the hardware and operator, if it were mine, I would resort to hydraulics. Wooden blocks top and bottom would maximize the applied force. Lube the heck out of the cylinder and apply the force slowly. Conceptually, it is kind of like pressing out a bearing. A big bench vice, arbor press, or bearing press would be needed.

Unfortunately, it is likely that the piston, cylinder, or both are going to lose some metal. Hopefully it won't be critical.

Best of luck.

sweaner wrote:Maybe you could use temperature. This is all just off the top of my not so mechanically inclined head. Freeze the whole thing. Then try heating just the cylinder to expand it enough to let the piston loose? Maybe?

I was going to suggest heat and cool, too. I was thinking a heating pad around the outside with dry ice in the piston.

Assuming you can get the o-ring out so as not to wreck things further, and that the piston is still jammed in, you could do the hot/cold thing by freezing the piston assembly overnight with the little piston hole plugged and then simply hold the piston assembly so that the piston itself is in boiling water for a minute or maybe less. The metal of the later pistons is so thin that might be enough.

Can't you just wedge a large flathead screwdriver in to bend the lower flange back a bit?

Thanks for all the suggestions, I'm going to have another go at it on my day off next week.

Fortunately I have several interesting green coffees in, otherwise I'd really be suffering!

Regards, Henry

First, welcome to the Yellow Caravel Club! Everyone knows the yellow version heats up fastest, lasts several millennia, makes the sweetest espresso of all colors and smells like lilacs in spring when used.

I would try heating the entire system up to boiling and let heat soak through—assuming you can still do this with water in the reservoir. Then try using medium-sized wooden dowels to tap the piston back to position at both top and bottom. My rationale for getting everything hot it because the tank et al is basic steel, something which will expand with heat and is relatively forgiving when worked. Use wooden dowels as if they were hammers. Hopefully scuffing in the cylinder will be minimal once the piston is righted, but take no chances with metal or plastic implements. You might want to place a dowel in the top, back it against a wall, and then tap on the opposite side of the piston from the bottom. Doing all this while hot will be a feat, to be sure.

I am going to guess that something in the piston mechanism is faulty because that is a very strange way to leave the piston.

Best of luck!