That should be all it takes...

Should being the key word here...


Try this.

Cycle the lever up and down a bit while lifting and turning the group assy. That might help it work its way out. Piston friction may be stopping you now and by moving the lever, you might be able to get the spring to (safely) help.
I did have to pry the clamp open a little to get things going.

There are no threads between the group and the base, just a smooth bore, so pulling with a back and forth twist is generally the best way to remove.

ciao

lino

lino wrote:I did have to pry the clamp open a little to get things going.

There are no threads between the group and the base, just a smooth bore, so pulling with a back and forth twist is generally the best way to remove.

Yes, prying the clamp open by tapping a little stubby screwdriver into the slot did the trick. The chassis then twisted right out as you described.

The piston has a little oval hole (marked with a dotted arrow) whose shorter diameter is ~3mm, and the piston cylinder behind the group has a similar hole (marked with a solid arrow) directly behind the group, about 1mm or so down from the "ceiling" as it were.

The screw (part #1154) holding the rubber washer (part #1130) is frozen. I'd be grateful for suggestions on how to loosen it. I will try tapping on the screwdriver with a hammer and maybe the vibrations will loosen it.

I haven't quite understood how these two holes work in concert. When the piston retreats, water in the boiling pot flows by gravity down through the hole behind the group, filling the chamber. But when the piston is forced up again by the spring, compressing the water in the chamber, why wouldn't the water just shoot back up through the same hole back into the pot? How is the water forced out through the group and not back up into the boiling pot?

timo888 wrote:While I am on the hunt for piston seals, and some tiny circlip pliers, let's have a look at the heating element:

image: http://www.aimsdata.com/tim/espresso/pe ... lement.JPG

Tim,
Think of a 2 cycle engine!!! The circles around the center bolt show n in your photo, are in the ceiling of the piston cylinder. They ( under the flexible washer) are the actual intake ports to fill the cylinder. When the handle is drawn down- the flex of this washer allows water to be sucked in. When the handle is released, the flexible washer is pushed against the intake ports and finds the only way out is through the exit port( the one you mistook for the intake port. It then is expelled through the group head.
You did ask about how to remove the screw . First is the rubber washer in good shape? I would be cautious of using anything other than mineral oil to act as penetrating fluid so as not to contaminate a flavor enhancing component that you may or may not be able to find a replacement for.

What he said...

Additionally, you may note that the outlet from the cylinder has a one way valve (out only) as well. The little rubber disk in the center of the group. I guess so that mid-stroke re-pumps are certain to take fresh water instead of the stuff over the coffee bed.

Also the washer and stuck bolt that allow water in from the tank should probably be left alone. There's nothing behind it besides a few holes, and that poor piece of rubber is getting old and tired.

The little hole in the piston is to allow water to continue to flow into the group even when the piston is above the port to the group. (don't think 2-stroke on that one... )

ciao

lino

mogogear wrote:The circles around the center bolt shown in your photo ... are the actual intake ports to fill the cylinder. When the handle is drawn down- the flex of this washer allows water to be sucked in. When the handle is released, the flexible washer is pushed against the intake ports and finds the only way out is through the exit port (the one you mistook for the intake port. It then is expelled through the group head.

Ah, I see. I poured some water into the 8 holes of the base and held it up and peered up into it, and thought the water seemed to be coming in through the oval shaped hole. Now that the thing has dried off, I've tried it again, tilting the side opposite the hole down. I see that the water entered from behind the flexible washer, and the area near the hole remained dry.

Is the flexible washer in good condition? I frankly won't have a baseline to compare it to (when I manage to unfreeze the screw) as this is the first espresso machine I've ever taken apart and my first encounter with flexible washers. I can say that the washer is intact with a clean edge, not crumbly. But I wouldn't know from sight or feel if it were too flexible or not flexible enough. When I swipe it with the tip of my finger, the tip of my finger gets stained black, if that's any indication of whether it needs to be replaced.

Regards
Timo

lino wrote:The little hole in the piston is to allow water to continue to flow into the group even when the piston is above the port to the group. (don't think 2-stroke on that one... )

The way things are now, the oval-shaped hole on the top of the piston is facing the rear of the machine, while the port to the group is on the front, of course. Should the oval-shaped hole in the piston be aligned with the front of the machine? Did I twist the piston when attempting to unseat the group assembly?

Regards
Timo

lino wrote:Also the washer and stuck bolt that allow water in from the tank should probably be left alone. There's nothing behind it besides a few holes, and that poor piece of rubber is getting old and tired.

Is it possible the flex washer had been absorbing lead during the first 20 years of use?
Timo

A relatively inexpensive way to find out:

http://www.watersafetestkits.com/html/contactus.asp

Regards
Timo

I received some buna-n o-rings in the mail from mcmaster.com (thanks, lino) and slipped one onto the piston, lubricated with Taylor in the red tube, reseated the group into the base, and let a few cups of water run through. So far, no leaks, and the piston feels very smooth. But I need a boiler o-ring (the boiler o-ring was carried off by a pesky house-sprite) so the tests had to be cold-water and only a few ounces.

Replacement boiler o-rings are on order. Hope they fit well enough -- couldn't find an exact match. Also ordering some additional piston o-rings in EPDM-material with a slightly smaller diameter than that of the buna-n o-ring. The buna-n o-ring fit perfectly and was just too easy to install, which has me worried. It can't be easy, can it? If everything fits well and continues to work, I'd be happy to send some of these o-rings out to those who may need them, at cost plus postage. I had to order enough for a lifetime.

The repaired piston o-ring leak has let me test the flex washer to see if it's in good shape. Apparently it's not. With the lever down, I gradually poured ~3oz of water into the 8 holes @ the center of the heating element, while raising and lowering the lever slightly to cause some suction to draw the water down into the piston chamber. When the water was all inside the chamber, I brought the lever up fairly quickly. Although some water sprayed through the dispersion screen, perhaps a third of it came back up into the boiling chamber. So the flex washer appears to have become inflexible with age and is not pressing back tightly enough against the ceiling of the piston chamber to close the holes off completely. Recalling the black water dripping into the tray, I'm thinking that the small flex-washer on the group may be too stiff and letting brew-water be drawn from the basket back into the piston chamber.

You may recall that the screw holding the flex washer is frozen. I have been unable to budge it, but fear that more force will shear the head off the screw. I've filled the piston chamber with mineral oil and let it soak overnight. Also tried tapping the screwdriver end a few dozen times with a hammer. Next stop, butane pencil torch. Way cool. I'm looking for one with a pocket clip. How have I managed without one all these years?

Regards
Timo

timo888 wrote:The repaired piston o-ring leak has let me test the flex washer to see if it's in good shape. Apparently it's not. With the lever down, I gradually poured ~3oz of water into the 8 holes @ the center of the heating element, while raising and lowering the lever slightly to cause some suction to draw the water down into the piston chamber. When the water was all inside the chamber, I brought the lever up fairly quickly. Although some water sprayed through the dispersion screen, perhaps a third of it came back up into the boiling chamber. So the flex washer appears to have become inflexible with age and is not pressing back tightly enough against the ceiling of the piston chamber to close the holes off completely. Recalling the black water dripping into the tray, I'm thinking that the small flex-washer on the group may be too stiff and letting brew-water be drawn from the basket back into the piston chamber.
Regards
Timo

Er, ah - before you attack Miss Peppina with flaming devices - have you considered that the flapper valve will have the weight of a column of water holding it shut?

My hunch is that if it works and doesn't look dreadfully corrupt, it should be left to flop about blissfully at peace - since you're running some risk of damaging the machine if you go after the poor screw with heedless vigor ....

Cheers (how <odd> to be the Voice of Reason):

Jim