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Thread: La cimbali M27 water dripping

  1. #1
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    La cimbali M27 water dripping

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi, My name is Layth, I am in Saudi Arabia, and I just installed this machine out of storage into our coffee shop. It is fairly new (2 year old) but through storage it has been visited by something (a rodent most probably) that ate the silicon hoses and some of the insulation on the wires. I brought in La cimbali service to shop to check on machine, and they said all wires are good, and all that needed replacing were the two silicon tubes .. which i did. But then i noticed that machine was leaking.

    When i opened it up, I noticed that there was a drip and it was coming from here :



    I am not sure what this is. I tried finding diagrams for the machine but never saw this part. I am still new in servicing the coffee machine myself, but i have no choice but to learn, since this is the second service people i call for this machine, and they are all sub standard and a rip off in the price of parts they sell.
    I am wondering if there was a silicon tube that was supposed to be attached there that goes to drain, or am i supposed to adjust the valve (but what would it do if I do that).

    The dripping only occures as machine is reaching proper temperature (so first 45 min after start), and it leaks around 2oz (60 ml). then stops dripping and all is good.

    here is a pic for the general location of this valve:



    I would appreciate any help

    and thanks in advance

    Layth

  2. #2
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    I'm not familiar with the inside of your machine, but it looks to me like the OPV (over pressure valve) - the large screw head is used for adjusting extraction pressure.

    If the drips are coming from around that screw then I would guess that there is a sealing o-ring underneath it that has decayed and is allowing a small amount of water past.

    Someone with more knowledge may come along to correct me, but I think as a general rule these valves can be disassembled by removing the screw and their internals serviced/replaced - where you'd obtain such parts in your country and how you adjust the pressure to the correct value again is a different question.

  3. #3
    Super Moderator Javaphile's Avatar
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    There should be a poly hose going from the fitting on the underside of the valve that runs to a fitting on the side of the catch/drain basin that the water from the drain area where you set the cups when pulling a shot empties into. The fitting on the bottom of the basin goes to your waste pipe/basin/bucket/whatever you use to catch the dirty water.

    MikeS is correct, that is the OPV. There is a set screw that holds the large end piece that you turn to adjust the by-pass pressure in place. The rough rule of thumb for adjusting it is once you have the pump pressure adjusted to what you want then with the pump running back the adjustment screw on the OPV out (After loosening the set screw of course.) until water starts to flow through into the catch basin and then turn the screw a half turn back in and retighten the set screw.

    In the attached picture the yellow circle shows where the hose attaches to the OPV and the pink circle shows where the hose empties into the catch/drain basin. The hose obviously attached to a fitting on the other side of the basins wall.

    DCP_1075-Resized 800.jpg


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  4. #4
    Senior Member artman's Avatar
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    You can unscrew the big screw with the slotted end (after loosening the grub screw on the side) and give it a clean/lube (food safe grease), there will be a spring inside that pushes on a rubber seal against a hole to create a seal. When enough pressure is present the spring compresses and water is bypassed. It will all be obvious when you take it apart.

    Not sure if I misunderstood Java above, but it looks like your machine is a rotary pump. My understanding for adjusting pressures is as follows.

    Fit a pressure guage on the group, lock in blinded PF. Use the bypass on the pump head to get 12 bar pressure, adjust the OVP in your pic to just drip at this 12 bar. This is for a safety feature so if your pressure goes high on the pump for some reason, the OPV will bleed off the excess.

    The next step is to adjust the bypass on the pump head to get 9 bar pressure for brewing.

    The pump by pass pressure adjusting mechanism can also be removed for cleaning/lube. Mine was jammed and adjusting the pump bypass made no difference to pressure, so I took it apart to clean and all was good. Here is a link to the thread:
    http://coffeesnobs.com.au/brewing-eq...tml#post263620

    Cheers

    Cheers

  5. #5
    Super Moderator Javaphile's Avatar
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    Sounds like that is probably the proper by-the-book method for setting the OPV's release pressure while the method I was told is a techs time saving in-the-ballpark method.


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  6. #6
    Senior Member artman's Avatar
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    Ahhh, re read your post and all now makes sense. Thats a good tip.

    The other thing I realised is that seeing water come out of the bypass during brewing indicates your pressures have gone wrong, as was the case on my machine with the jammed pump bypass.

    Cheers

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    thank you artman and javaphile.

    Couple of questions though.
    1- I am having a hard time ordering portafilters for this machine since i tried a while ago to get a naked portafilter and even though it was listed as for this machine and so, it did not actually fit. so it will be hard for me to get a pressure potafilter to test the pressure that way. What is the best way to order a portafilter and not go wrong? what measurements should i give the company like espresso parts etc.

    2- the machine has a pressure gauge .. is this somewhat accurate? can i use that pressure as group head pressure or not? right now the pump is set to 9 on that pressure gauge.

    3- i will probably try javaphile method since i do not have the equipment (but maybe turn 1/4 turn instead of 1/2 a turn). Is it safe to assume that after i adjust that way, i can/should readjust the pump pressure to higher than 9 and and lower than 12 and see if i get any dripping to make sure that OPV is working safely?

    4- there is no where to attach it in the drain collection under the drip tray. but there is really nothing attached to there. the two large hoses just sit in it, so maybe this hose should join them and sit as well ... here is a pic:






    but thinking logically about it, should it even be connected to the drain, if the valve drips this would mean something is wrong, something is adjustes off, and if it goes to drain, i will never notice that, if it drips and makes a mess i will. or am i thinking the wrong way of this?


    Thank you so much guys for your replies. it is really helping me out.

  8. #8
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    I replied to this earlier but i guess my post got lost somewhere (this is the second time and i hope i am not doing something wrong that the moderator will be upset).
    Thank you artman, and javaphile.


    if you dont mind i had couple of question in regards to this:
    I am guessing i will be following javaphile method since i dont have access to pressure gauge portafilter :
    1- is the gauge on the machine accurate ... it is set to 9
    2- is it safe to understand that if i used that method javaphile and adjust to 1/4 turn instead of 1/2 turn after water starts flowing from OPV then i can test that my setting is correct by readjusting the boiler pressure up a bit to see if the OPV will flow and at what pressure that will happen?
    3- In regards to to the hose that is attached to the OPV in your picture to the catch drain. i guess it would just sit in the catch drain like the other two hoses right now in my machine's setup. see pic below. But i was wondering doesnt that kind of defeat the purpose of the OPV? meaning if it starting to gum up or fail or if it is missadjusted ; if it is attached to the basin, i wouldnt notice it leaking, where as if it leaking i would? or am i missing something.








    Thank you guys again for your answers,
    Layth

  9. #9
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by laythss View Post
    1- I am having a hard time ordering portafilters for this machine since i tried a while ago to get a naked portafilter and even though it was listed as for this machine and so, it did not actually fit. so it will be hard for me to get a pressure potafilter to test the pressure that way. What is the best way to order a portafilter and not go wrong? what measurements should i give the company like espresso parts etc.
    Giving them the brand and model number should be all they need to get you the right portafilter. As far as I know La Cimbali uses the same portafilter on all their commercial machines.

    2- the machine has a pressure gauge .. is this somewhat accurate? can i use that pressure as group head pressure or not? right now the pump is set to 9 on that pressure gauge.
    Baring a problem with the gauge it should be giving you an accurate reading of the brewing pressure.

    3- i will probably try javaphile method since i do not have the equipment (but maybe turn 1/4 turn instead of 1/2 a turn). Is it safe to assume that after i adjust that way, i can/should readjust the pump pressure to higher than 9 and and lower than 12 and see if i get any dripping to make sure that OPV is working safely?
    You can use the built in gauge to use Artman's method.

    4- there is no where to attach it in the drain collection under the drip tray. but there is really nothing attached to there. the two large hoses just sit in it, so maybe this hose should join them and sit as well ...

    but thinking logically about it, should it even be connected to the drain, if the valve drips this would mean something is wrong, something is adjustes off, and if it goes to drain, i will never notice that, if it drips and makes a mess i will. or am i thinking the wrong way of this?
    Your drain setup is different than the machines I've seen but regardless the OPV needs to be connected to the drain. If the OPV is actuated there can be a lot of water coming out of it at high pressure which would cause the water to spray all over the machine. That water needs to be directed to the drain. Remember, water + electricity = a very bad day!

    Once you've cleaned/rebuilt the OPV and adjusted it there should be no more drips coming from it.

    Tune your ear to the sounds your machine makes. If your OPV opens you will hear a new/different sound which will let you know you have an issue that needs to be looked at.


    Java "Cimbali's rock!" phile
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