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  • 6910 - Faulty 3 way valve?

    I am not sure the 3 way valve is faulty, but, here are the symptoms.

    I first noticed the pressure gauge was not working properly, then it stopped.
    Then I noticed the 3 way valve was not releasing water into the drip tray.
    When I used some powder cleaner in the P/F it bocked the little hole in the cleaning disk.
    The pressure built up so much I could not remove the P/F for some hours, it was jammed tight, The pump stopped pumping as the pressure was too high.

    I tried a 50/50 vinegar solution many times, left it sitting overnight.
    Sometimes the pressure gauge moved,

    So I swapped the 3 way valved out with known good one, it was operating in another 6910.
    No change.

    I removed the brew thermoblock, made sure all the lines were clear, soaked the brew thermoblock in vinegar solution, blew out all the ports with compressed air, and re assembled.

    No change.

    Since then I have swapped the original non functioning gauge into a functioning machine and it works fine.

    Makes good coffee!!

    So, hope I have not missed anything in what I have done.
    Do any of the EM 6910 experts have any pointers, I have wondered about the ecu, but not sure what to check.

    Robin

  • #2
    Hi Rawill
    Did you check this path in the brew thermo. A blockage in the spot shown will stop the 3 way from venting and the pressure gauge.
    I have found that there is a constriction where the copper tube out is cast into the drilled vent channel and it is easily blocked with grounds and oils. It can be difficult to clear. Click image for larger version

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    • #3
      If pf gets stuck, should be able to open hot water tap to let pressure out

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      • #4
        Originally posted by Xanthine View Post
        Hi Rawill
        Did you check this path in the brew thermo. A blockage in the spot shown will stop the 3 way from venting and the pressure gauge.
        I have found that there is a constriction where the copper tube out is cast into the drilled vent channel and it is easily blocked with grounds and oils. It can be difficult to clear. Click image for larger version  Name:	Relief vent.JPG Views:	37 Size:	76.4 KB ID:	825790 Click image for larger version  Name:	Cross section.JPG Views:	21 Size:	25.3 KB ID:	825791
        Many thanks.
        After I posted I rang a supplier to order a new collar. He mentioned something very similar.
        And you comment not only confirms what he said, but also confirmed something else I was puzzling over.

        After one of my soaks, in 50/50 solution, the next morning the gauge went up to normal, I thought YES, got it.
        Next try, it the needle lifted a bit, then stopped, next time it never moved.
        I suspected a blockage in that port, should have persisted, but got fooled by the fact that the air went through, but I thought too slowly.

        Again, many thanks

        Rbn

        Note. Yes I did check it. took the thermoblock out, blew out all the ports, I was sure I could feel air coming through, however, at 120 PSI it was very weak coming through, I thought, oh well, it is a very small port, so that is probably correct. I will try again.

        Comment


        • #5
          Hi Robin
          All good if clearing that fixes it. I have often wondered about putting a drill up that hole but never been game to try it - maybe a last resort! I managed to poke out a blockage there with a thin bit of wire - there wasn't much of a gap at the end of the tube. Just be careful undoing the cap nut as per one of my other posts. The tube is very fragile, although it sounds like you have already managed to undo it successfully already. While you have it apart it may also pay to check the copper "U" tube and "T" at the end of it.

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          • #6
            You are so right about undoing it. Would be so easy to "unscrew" the little tube and ruin it!

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            • #7
              Any progress to report yet Robin?

              Comment


              • bez2go
                bez2go commented
                Editing a comment
                Thought I would add a few observations. I have fiddled with quite a few of these now and have found blockages can occur ANYWHERE ( and everywhere lol!) fro the thermoblock through the copper piping , into the solenoid valve itself AND beyond to the end of the silicon tube attached to to the solenoid. And have had to feed a piece of wire up through the nipple on the end of that tube( that exits into the drain tray). Also yes that little bit of piping out of the thermoblock IS fragile and have had x2 breakages, the first left a stub of piping so I could reattach with a bit of work (remove the olive from the broken fragment and reattach and also file a lilttle of the mounting point to enable the brass nut to displace backwards toward the thermoblock all reconnected and worked fine) however the second resulted in the piping shearing away completely-with nothing left! so I drilled a hole tapped a crude thread and screwed in a brass fitting onto which I could screw one of those plastic tubes that are commonly used on all manner of machines, bypass the copper U piece and screw into the copper T connected to the solenoid After reassembly , it seems to be working but will only use it as last resort

            • #8
              My gauge stopped working a few years ago and I didn't notice as it is in a weird place,does it serve any real purpose other than going up and down and of course stopping

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              • Xanthine
                Xanthine commented
                Editing a comment
                This is often a sign of a blockage and the '3-way' no longer working - worth checking.

            • #9
              My machine seems to work ok apart from the gauge, what does the 3 way do? And are there any links for a maintenance service or guide? Thanks for taking the time to respond.

              Comment


              • Xanthine
                Xanthine commented
                Editing a comment
                The so called '3-way' acts as a pressure release for the group at the end of the brewing process. It prevents you from getting sprayed with hot water and coffee when you unlock the group handle by releasing the pressure down into the back of the drip tray. If you lift out the rack from the tray when making an espresso or backflushing with a blind filter you should be able to see a short 'sneeze' of water from the drain tube which enters the notch at the back of the tray. The thin capillary tube to the pressure gauge branches off at the "T" in the line between the brew thermoblock and the 3-way solenoid. The 3-way can fail through blockage, coil burnout or fracturing of the brass barrel housing the plunger down through the centre of the coil. Regular backflushing helps to keep all of this clear.

            • #10
              thanks for the explanation i have back flushed and descaled a few times in the past few days but no pressure gauge yet, i will try your trick later today to see if any water comes down the back of the rack. I havent ever had any back pressure issues when unlocking the group handle so maybe it is working, I did push a wire about 2 inches this time up the vent hole without going too far and descaled afterwards so will check this afternoon for gauge and drain water. thanks again. I dont have any leaks if that is an indicator?

              Comment


              • Xanthine
                Xanthine commented
                Editing a comment
                Don't be afraid to push the wire too far - the vent hole is 'blind' at the top so you can't really do any damage there. Also, if you do find that the 3-way is working OK the problem with your pressure gauge is either a blockage in the "T" or capillary tube or a faulty gauge.
                I noticed you mentioned de-scaling. A better option for clearing this area is to use a specialised 'detergent' such as Cafetto which is placed in the group basket on top of a blind disk and running the back-flush program.

            • #11
              hi when you back flush does any flushing actually go up into this vent hole? I just bought some liquid descaler from woolies, oh well i will give it a try. Is it worth unscrewing the gauge tubing and soaking it in descaler? or just accept the gauge doesnt work.

              Comment


              • Xanthine
                Xanthine commented
                Editing a comment
                Yep - a small quantity of air and water (with the detergent) but under quite high pressure. The backflush program repeats this half a dozen times and then the solenoid valve remains open for a while on the last longer flush. In the normal brewing process some of the finer coffee grounds and oils pass through this path and coat everything, ultimately causing a blockage. Descaler wont touch these oils, it takes a specialised 'detergent' to effectively shift them. Not much of the flush enters the gauge capillary line.
                If you have the covers off you could try carefully dis-connecting the capillary to the gauge at the "T" and force water in through the vent hole in the thermoblock using a syringe full of water and suitable tight fitting adaptors made from bits of plastic tubing. With a bit of ingenuity you may be able to adapt the syringe to the end of the gauge capillary as well to see if the needle moves. This should help you locate just where things are blocked. Just try not to spray any water around inside the machine as it could cause damage when it is powered up.
                I would still strongly recommend using a proper coffee cleaner though. Either the Sunbeam tablets or Cafetto - it's amazing how this stuff shifts coffee oils and grounds. Regular backflushes with this stuff are far more effective than descaling in keeping things working.

            • #12
              Hi, I used the sunbeam tablet this afternoon, with some vinegar in it, but may hit it again in a few days. Do you mean to force water in via syringe to make the gauge move? Or air? You mentioned "detergent" The descaler i got form woolies has anionic surfactant in it and citric acid and tartaric acid, it is fron Cleanbean.com anyway i have it so will try it. and will look for Cafetto too. thanks again

              Comment


              • Xanthine
                Xanthine commented
                Editing a comment
                Descaler (Vinegar or tablet) goes in the water tank, Coffee cleaner in the group handle. I would not suggest mixing the two but use as totally separate operations. Just air in the gauge capillary should be able to move the gauge needle but use water to test the path from the vent to the solenoid valve.

            • #13
              ok thanks i was wondering last night if i was to soak the gauge tubing in liquid descaler 50/50 say or at least try and force some up the tube without taking it apart? Oh and i used the descaler tablet in the tank with some vinegar. cheers

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              • #14
                I pulled the machine apart again and took off the top brass connector for the gauge and using a small syringe squirted air down the pipe and the gauge moved so I figured that wasnt the problem, the felt washer under the connector was perished, I thought that was the problem so i made a new one and put it back together and fired it up. No difference. So will try a descale again and see what happens.

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                • #15
                  well the important thing it still makes good coffee, i have learnt that i over dose it so will try to cut that automatic way of doing things. no gauge but stuff it i will try and find some caffetto cleaner. thanks for the support.

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