La Cimbali M20 Lever Leaking

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Joseph69

Postby Joseph69 » Mar 14, 2019, 10:59 am

Hello All.

I'm Kevin, new to the group and firstly just want to say thanks to the people who contribute here. The posts have been very helpful in getting a La Cimbali M20 Lever back to near working order. Trouble is now I am stuck and hopefully someone can point me in the right direction. I have replaced all the group head gaskets from looking at the lever diagrams on part sites. While I was doing this I also took the advice from people on this site and replaced the springs as they were rusty and one was broken.

When testing the machine the first time the pressure gauge was faulty, the needle was not at zero and rose quite quickly into the red so I immediately turned it off. The safety valve on the boiler did not let off so I figured it had not got TOO hot. There is a valve above the glass sight for the water level that was continuously hissing but I took it off and cleaned it up and now it seats properly and doesn't hiss. I replaced the pressure gauge with a new one and switched her on to see if I was going to get a win. The gauge did not move for about 10 minutes then started to rise to 0.5 but going above that seemed way to hot and it was not long before the safety valve did let off a blow of steam. I turned it off and adjusted the thermostat back two turns. I am doubtful the pressure gauge is faulty but the temp and pressure seemed a lot higher then the gauge reading. The line has been taken off and cleaned, scale was minimal if any.

I also noticed a small drip which made me concerned if I got ALL the gaskets! I tried pulling a few shots and well something isn't right. I have uploaded a video to show the drip and the way water just gets dumped threw the portafilter when I pull the lever down. On the lever returning there is minimal resistance and spurts water. Steam Tap works great, so does the hot water but why is the water just pouring out. I thought the coffee may not have been ground fine enough but it did the same ground down to baby powder.

Here is the video if anyone can offer some tips it would be greatly appreciated, shes been on my bench for ten years waiting to shine again. :( :oops:


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grog

Postby grog » Mar 15, 2019, 7:08 pm

Video isn't working so not clear what may be going on with the group.

As far as your boiler pressure issue, since you have a brand new pressure gauge, we probably remove the gauge itself from the equation. It's weird that the OPV is venting at .5 though, no way that should be happening. It's also quite strange that you are getting enough pressure after just ten minutes from cold for that to even happen, even if we assume something else is going on such as defective pressurestat, scale (or other) blockage in a line, etc. Did you descale all of the plumbing or just the pressure gauge line? Also sounds like maybe you want to clean the OPV.
LMWDP #514

Joseph69

Postby Joseph69 » Mar 16, 2019, 10:30 am

Hi, thanks for the reply. I have taken the lever out and checked to make sure nothing was wrong and that all seemed OK. While the piston was out I had a better look at workings and figure it has to be the shower screen. It's the one part I missed that should have been replaced. It felt loose and looks like the water is coming through the edges and not spread over the shower screen. I have ordered a replacement, hopefully it will make a difference. I removed the Pressure gauge and replaced it with the old one again. It was not returning to zero but I still felt that its reading was accurate. When I turned the machine on to let heat up it eventually rose to around 1.6 and I adjusted the thermostat to stay within 1.5 - 1.6.

I tried pulling another shot but this time I was very gentle when pulling the lever down and things were a little better but I still water streaming to quickly. On return the lever shows resistance and doesn't spurt out the portafilter like in the video. I will do some more cleaning and test the pressure gauge while i wait for a new screen and post a video of the result.

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grog

Postby grog » Mar 16, 2019, 10:53 am

Are you lubricating the piston seals and the piston bore before re-assembling? That will also help create a better seal and smoother lever action.

Glad to hear the pressure issue appears resolved. That sounds like a high pStat setting though - maybe try turning to 1.3 or so. I run mine at .8 and still have plenty of steaming power.
LMWDP #514

Joseph69

Postby Joseph69 » Mar 25, 2019, 8:55 am

Hi All, I'm back again but unfortunately not with much success. I removed the pressure gauge to test it and in comparison to another gauge i found its reading to be about the same. So I am hoping it is close to accurate and I will buy another but I figure it is somewhere in the ball park of being correct.

I purchased a new shower screen in hope it would solve the problem of the water coming out so fast. Logic AND steam lead me to thinking its a pressure problem during pre-infusion?? ( I presume that is the correct terminology). When the lever is pulled down (gently) water pours out and steam under pressure. The videos I have seen, have a nice even pour from the screen, nothing like mine. When I try to poor a shot she starts pouring on the down stroke. By the time you count to ten things are stuffed. New screen made no difference, pressure from the puck, I have gone well overboard to try slow it down but no luck.

I feel it is do with temperature/pressure and with the gauge being in question I have turned the thermostat down to just on steam coming from the wand. She still blows her top off when I try to poor a shot. I have checked all the gaskets, run smooth, no water above springs, no leaks below. I put in a blind filter to check back pressure from lever and it wasn't moving.

Anyone with some a idea what I am missing.

Here is another video of the last test on below .5

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grog

Postby grog » Mar 25, 2019, 9:45 am

I agree that your pressure gauge is accurate. Re: water flow, when I saw the first part of the video I thought "you just need to grind way finer" but then when you show the water flow without the PF in place, it's clear something else is going on.

If you're certain you have all the seals installed in the correct orientation (both the soft top seal and stiff bottom seal can be installed upside down), I'm just not sure what could be causing the high flow. The top soft seal should have the u-cup facing down and the stiff bottom seal should have the larger edge at the bottom, with a soft o-ring inside it against the piston.
LMWDP #514

Joseph69

Postby Joseph69 » Mar 25, 2019, 11:30 am

Cheers Grog,

I took out the lever to check the gaskets orientation and the bottom gasket was upside down. Smaller diameter at the bottom, so I flipped it around and fingers crossed it may make a difference. I had a look at a diagram where I purchased that gasket and it looked like it was smaller down. I want to turn it on and test it but better wait until morning. Will post the outcome :D

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grog

Postby grog » Mar 25, 2019, 11:45 am

So the way you had it originally installed was consistent with the diagram you have? I would leave it that way. I might be remembering the orientation incorrectly.

EDIT: yep, I looked at some pics of my own pistons and you had it right already. Apologies, made you take it out for no reason!
LMWDP #514

Joseph69

Postby Joseph69 » Mar 26, 2019, 5:47 am

Well I turned the gasket back to its original position, looks correct to the diagram. Thanks for your help Grog in confirming there orientation. If the pressure gauge is correct I have turned the thermostat down to .3, just when steam starts from the steam want. It still pushes huge amounts of water into the chamber. This seems to smash the puck immediately and let water and steam through. By the time the leaver is lifted there is no resistance, a little at the top.

When I got the M20 it was missing the portafilter, I purchased a new one that I presume is compatible with the machine. I am either lacking back pressure from portafilter back to chamber, or there is far too much pressure coming into the chamber.

What the :oops: :x

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grog

Postby grog » Mar 26, 2019, 9:53 am

I strongly suspect the latter, based on water flow in your video without PF in place).

You might want to post a thread in the Repairs forum with a title that references 'water flow issue' or something along those lines. Might get some others to weigh in, since the issue isn't necessarily specific to your machine.
LMWDP #514