But my portafilter uses a basket for which I use a 57 or 58 mm tamper, so I think that's a different portafilter.

That is a 58 mm portafilter The standard Elektra group on the larger machines is a 58mm. Sorry, I did not mean 53 mm (looked at too many pictures trying to find the right one).

Indeed, James, I have one of those new 58mm standard Elektra portafilters, which I got from Stefano for my T1. I also have some "vintage" 1999 T1 portafilters, and their portafilter lugs/ears are much more slanted (though still not as steeply as Joep's). I doubt that the portafilter is the problem; it doesn't show any particular signs of wear, and whether it's flat or not, it's still just 2 pieces of metal smashing the basket against the gasket. Doesn't need to be flat to do that, as long as it's thick enough to press hard enough.

And it seems to be doing so--Joep notes that it seals fine for part of his shots, indicating something slowly coming out of place. Since the portafilter isn't moving, it's clearly not that, so I suspect a problem with the gasket, either inferior quality, improper seating, or just some gunk in it screwing it up. Both of these guesses seem consistent with an issue which is solved by gasket replacement, at least temporarily. I don't think that a diagnosis of "you have the wrong portafilter" is consistent with the observation that it actually works fine with a fresh gasket replacement.

Thanks Nicholas, I know you and quite a few others have much more experience with Elektra products than I do. My thought was that the steeply ramped wings may allow the portafilter to loosen up after the pressure builds in the basket because there would not be as much contact area between the PF and the thread if they do not have the same profile. New gaskets could initially solve the problem until they become fully seated. I only suggested he may have the wrong portafilter, I did not mean to insist that is the case.

Thanks, James

shadowfax wrote:I doubt that the portafilter is the problem; it doesn't show any particular signs of wear, and whether it's flat or not, it's still just 2 pieces of metal smashing the basket against the gasket. Doesn't need to be flat to do that, as long as it's thick enough to press hard enough.

I believe this is not true Nicholas. You could smash flat against a perfectly good gasket and form an initial seal, but if there's too much clearance behind the tabs OR if the groove has a wallowed-out spot....this could allow the portafilter to "rock" and thus lose the seal and allow the hot contents to spew.

shadowfax wrote:Since the portafilter isn't moving, it's clearly not that

But the OP says that the portafilter DOES move!

The fact that the portafilter physically MOVES after the pressure starts to build is very telling I think. And it makes me believe the problem is almost certainly not related to the gasket. The gasket apparently seals fine, allowing the pressure to build (plus, I believe the OP said the gasket is new).

Joep wrote:By the way, also when it doesn't 'explode', the portafilter handle comes up a bit in the first couple of seconds after initiating the brew process when pressure builds up, and comes down again when I stop it.

If I understand correctly, Joep is talking about up and down movement. I experience this every day on my Elektra, although it's very subtle unless you hold the portafilter handle during brewing or watch it very closely. One thing that puzzles me is that Joep describes exactly the opposite of what I see: When the pump engages, it slowly pushes the portafilter down, I assume it's the flex in the system as pressure is applied, the water forcing the gasket against the portafilter and then against the group bell channels for the ears. When brewing ends and the 3-way valve opens, it jumps up in my hand slightly as the pressure is relieved. I assume Joep just switched his words around--can you clarify, Joep?

If your portafilter is moving laterally, i.e. the the pump is forcing it to back itself out of the group, this is a huge problem. I think, however, that it's MUCH less related to how the ears mount in the channel and more with how lubricated the gasket is with coffee oil. To whit, try this: get some food grade grease, the type used for lubricating steam wand assemblies (Dow Corning 111 is good), and lube up your gasket on the portafilter side. Now lock with a blind filter, hit the brew switch, and watch it slide out. This won't happen on every machine, but it definitely does on my old Elektra. This can happen naturally from coffee oil as well, depending on how often you use detergent to backflush, and how much coffee ends up in contact with the gasket. If you want to get rid of it again, simply do a good portafilter wiggle with detergent in the backflush disk till your gasket locks nice and tight. A really clean one will lock it quite tightly. Anyway, this doesn't even sound like what Joep is describing...

Forgive me for doubting you guys, but considering this is a home machine and the pictures I have seen so far of the portafilter, I highly, highly doubt this is from wear and tear on metal (such as wallowed out spots or a worn down channel. I'm a lot more prone to suspect something along the lines of a moving gasket, having seen that type of crap on Elektras. That's one thing I will say about Elektras--their group gaskets are absolutely pathetic compared to LM, Synesso, and Faema gaskets (and other flat ones). Joep actually has a flat-faced one, which seems nicer than the round ones for my T1. My gasket is finicky about leaking if it's even slightly dirty, though it starts to leak immediately.

Whew, what a responses, thanks!

I made some pics of the group head:




The gasket is indeed practically new.

And indeed, my portafilter moves only up and down, not sideways. I really think my handle moves up when I start, but I would have to check tomorrow.

I do see by the way that the slot for the wings is much less steep than the taper of the portafilter wings...

shadowfax wrote:My gasket is finicky about leaking if it's even slightly dirty, though it starts to leak immediately.

Interesting. I can see how a round-section o-ring might not be as robust a seal as the flat gaskets seen in many other machines, but if the leaking in caused by upward tilting instead of rotation then there is almost certainly a geometry problem of some kind.

It was my understanding that Joep was seeing his portafilter shift upwards markedly, not gradually or slightly. He also seems to have indicated that the gasket leaked even when cleaned

Joep wrote:Well, I had cleaned everything when I installed it....
<snip>
What do you think about the fact that my portafilter lifts up when I engage the pump? Is that normal for the Elektra?

Joep wrote:I do see by the way that the slot for the wings is much less steep than the taper of the portafilter wings...

WOW! Talk about real-time response!

I'm not sure if this is meaningful but I do notice that the pictures make it seem as though the front part of the right side groove is worn to expose the brass, but the tail end is still chromed. Perhaps it's just the action of the flash...

Joep wrote:And indeed, my portafilter moves only up and down, not sideways. I really think my handle moves up when I start, but I would have to check tomorrow.

I'll be interested in this too....

Do you have another portafilter to try? I wish you were closer, I would send you one of my LaMarzocco portafilters to see if it fits tight enough to hold the brewing pressure

No, I don't have another portafilter. Buying another one is not what I want, although I wouldn't have to buy one complete with handle, just the cast part.
But since I'm more or less also looking for a machine with easier temperature control and a pressure gauge, I wouldn't want to spend much on this machine if you get what I mean..