Hello all,

It's been awhile since I last visited the forum, I've been enjoying my L1 for the past couple years. However, even with routine maintenance I've been running into some issues that a clean and lube won't fix.

First of all, my shot volumes have gone down. The catch point of the lever is similar to before, but now there is a little puff of air sound and the lever then slips up to around the 11:00 to 11:30 position before fully engaging. I'm getting about 20 grams per shot.

Sometimes, I'm able to pull the lever down again after the first puff of air, and this results in a shot volume, catch point, and timing I'm more accustomed to.

However, after almost every shot, the chamber seems to actually build pressure and there is continuous dripping through the puck. This could go on until the entire reservoir is emptied. I have to slowly loosen the portafilter until there is a huge sneeze, then the dripping stops altogether.

This behavior has persisted even after cleaning out the gunk, removing and relubing all gaskets. The gaskets are the Cafelat replacements but are probably over a year old by now. To the naked eye they all seem intact and pliable.

Any suggestions would be greatly appreciated! Thanks in advance.

Not to discourage you here but Londinium has a support forum. Owner Reiss often offers support.
https://londiniumespresso.com/~londes/support

To me it sounded like your piston seals are either not installed correctly or not working right, which is weird because you had it working for a while, and silicone usually doesn't get hardened and fail like the rubber seals. Have you got one of the spare piston seals from Londinium to test? On some machines the newer Londinium seals can work better than Cafelat's, there are some what appeared to be minor manufacturing variation between the group heads.

Another very unlikely suspect is the O-ring in the group sleeve, but I don't think the symptoms that you're describing could be attributed to that.

Another curious and perhaps relevant question, when you were installing the piston, was there any slight friction due to snug fit between the piston and the cylinder, or does it just move in and out easily?

I usually have these symptoms when I grind too fine or the water temp is too high.

I would contact Reiss or simply post something on the Londinium forum. Every 2-3 months the same symptoms occur on my L1, but a little clean up and some dow 111 is all she needs to get back to her usual self.

I'm also using cafelat's silicone seals. I believe silicone seals won't harden like rubber seals. They will wear or tear.

You can also look at this thread for some more info : Londinium piston removal

Replace all seals including the shower screen seal. Test your seals using a blind filter.

Thanks for the replies everyone.

I will reach out to Reiss on the forum later this weekend. For some reason the site wasn't loading well on my Safari browser, but Edge seems to work.

I'm fairly certain the piston seals/gaskets are installed correctly. I always take a picture before removing them and draw a diagram so I don't put them on wrong. I think I was getting some leakage around the group gasket after the latest reassemble, so I took off the screen and gasket and lubed it up more thickly, will try later today. This shouldn't affect the shot volume, should it?

Regarding water temp, I've had it at the factory setting since receiving the machine. For grind settings, I usually dial in for 30 grams out in 25 seconds. with 17 grams of beans. This was working fine until recently. It's a Monolith Conical so I highly doubt it's a grind issue.

I did some more searching on other forums and the linked threads. It seems that a small number of folks have had issues with the Cafelat seals, though rare, due to slight manufacturing variation of the piston. I also wonder if there are little micro tears at the edges that I didn't perceive on initial inspection. To answer a question posed, the whole assembly doesn't slide in easily per se, but maybe with a bit less resistance than there should be. I think the easiest step will be replacing the piston seals with new ones, and using a healthier amount of lube everywhere this time around. I didn't realize that there are newer gasket versions available from Londinium. I'll start out by reaching out to someone at Caffe Lusso to see if they can send me some Bosco gaskets to try. If these don't do the trick, I'll contact Reiss and have them sent out from England.

If you have portafilter sneezes after waiting a reasonable amount of time then your plucks are too dense, loosening the grind to see if it would help with the problems will take all of 5 seconds. Beans can also affect the plug density, not just grind and temp.

I tried pulling a few more shots yesterday and today with different grind settings.

No matter the grind, the catch is still way too high, around 11:30 or so, and I get 15-20gm out before it's just drips. If I do a second pull just after the first drops, sometimes it will catch around 10:00 as it used to, but usually not. This leads to a greater shot volume as expected.

If I grind more coarsely, I do not get a portafilter sneeze. Unfortunately, this causes the shots to run way too fast. A single pull still only gets me around 15-20gm out, but in around 15 seconds. With a second pull mid shot, I will get around 35-40gm out in 20-25 seconds. It streams out after the second pull. To me this means that the pressure above the puck on the first pull is way lower than expected.

If I tighten up the grind to get a more proper flow early in the shot, then the machine never really depressurizes unless I release the portafilter. What I mean by this is that the entire volume of the tank would flow through the used puck until empty. One time I had the drip tray half full before I caught it. It's like there is a valve that is remaining open to boiler pressure until I fully disengage the portafilter.

What you're experiencing is simply a piston or seals slip. Your seals aren't able work as they should when the puck creates normal pressure in the group.

The L1 has an opened thermosiphon which draws it's brew water straight from the boiler. It's simple thermodynamics. The valve that allows the water to go from the tank to the boiler is a 2 way solenoid valve. It's opened when the pump is working in order to fill the boiler when the level probe send a low water signal. So unless the pump is running, non-stop, the whole time you pull a shot, which could only be wizardry on the L1... there is no valve stuck opened. My guess is that your seals are not able to do what they're supposed to do so the water from the thermosiphon is not always contained between the seals a sometimes find it's way down, through the puck.

You need new piston seals.

I could be wrong though, but this would be my guess. Again, contacting Reiss is the best way to take guessing out of the equation. The L1 is a very simple machine. I would bet my lunch money that your seals are the culprit here.