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Bezzera BZ99 issues

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  • Bezzera BZ99 issues

    I’m having problems with my Bezzera BZ99. Today it took much longer to pull a double shot to 1:1.5 ratio, around 90 secs instead of the usual 30, I’ve tried to grind coarser but made no difference. It appear that the quantity of water coming out from the head is much less than it should be. I’ve had this happening in the past a couple of times and it was fully resolved with a chemical clean, but this time running the cleaner with blind filter twice had no effect. This is my first machine and I’ve never had any issues before, can someone help me to troubleshoot the problem? TIA

  • #2
    Flow test the pump.. should be at least 250ml in 30 sec. try it without shower screen if you want.

    It might need a descale too. Maybe some scale is blocking things up

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    • #3
      Originally posted by Jackster View Post
      Flow test the pump.. should be at least 250ml in 30 sec. try it without shower screen if you want.

      It might need a descale too. Maybe some scale is blocking things up
      Thanks, I’ll do the flow test in the morning, too noisy to do it at nighttime!

      How do I descale the machine?

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      • #4
        So I’ve descaled the machine as instructed by a couple of videos and it worked, I got 250ml in 30 seconds now. I hadn’t measured before, but it was definitely less than half that. Thanks Jackster!

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        • #5
          I spoke too early..... after a few boiler and exchanger flushes to remove the descaler the machine is back to just over 100ml in 30 seconds. Should I give it another descaling cycle, maybe only to the exchanger? What else could be the reason?

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          • #6
            Sounds like you have a physical blockage again from scale or a failing pump.

            When you do a backflush with a blind filter are you getting around 10 bar on the gauge? If it is very low like 4-6 bar then pretty good chance your pump is stuffed.

            Also did you do as Jackster suggested and remove the shower screen and group seal?

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            • #7
              Originally posted by roosterben View Post
              Sounds like you have a physical blockage again from scale or a failing pump.

              When you do a backflush with a blind filter are you getting around 10 bar on the gauge? If it is very low like 4-6 bar then pretty good chance your pump is stuffed.

              Also did you do as Jackster suggested and remove the shower screen and group seal?
              My machine doesn’t have a pressure gauge so I cannot say what the pressure does.

              Yes I did remove the shower screen, I do that every evening to clean it so I know the problem is not there. Bear in mind it’s not a E61 group.

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              • #8
                Ah ok not E61, if you are close to the Gold Coast, Qld I could lend you a pressure gauge portafilter to help diagnose. As if you are getting low flow and it won't get to 9 bar there is a good chance your pump needs replacement.

                Is your a tanked model with a vibrating pump or plumbed in with a rotary pump?

                Since this has a different group you could have a blocked or faulty solenoid which is not opening enough to provide the full low rate.

                Have a look at this parts diagram here;
                https://www.coffeeparts.com.au/parts...-and-solenoids

                It will take some work but you could removed the group solenoid and clean/soak in descaler to remove scale. Then see if the flow rate increases. The solenoid in the group is what opens up the water flow when you press the button/s to make a coffee, is uses a magnet to move the solenoid up and down and there is a spring which holds it closed when not power is applied.

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                • #9
                  BZ99S so tanked with vibration pump. Thanks for the diagram, do both version have the solenoid or only the plumbed? If mine has it too I’ll have a look how difficult or time consuming is to remove it and go from there.
                  I’m in Brisbane but I come often to the Goldie at the weekend, I might take up your offer for the portafilter if I’m still stuck.

                  Comment


                  • roosterben
                    roosterben commented
                    Editing a comment
                    Both versions have the solenoid in the group as unlike the E61 groups (manual versions) anyway, you don't have a physical lever to open up the water lines. You press a button and that engages (give 240 volts) the solenoid which drops down and allows pressurised water to flow from the heat exchanger (which cools that water in the boiler down towards 93 degrees), which is being fed by the boiler.

                • #10
                  I’ve removed the top cover and found that the machine does not have a separate solenoid as shown in your diagram, only the 3 way solenoid which connects directly to the group as shown below. The pipe on the right goes to the HX and the one on the left to the head.
                  Click image for larger version  Name:	84EFF1A7-C704-400B-A0E7-F8837310B254.jpeg Views:	0 Size:	68.2 KB ID:	831613

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                  • #11
                    Item 1 in that drawing is the restrictor jet for the group head. There's probably something stuck in it, scale most likely. You probably cleaned it out then a little bit more got sucked into it afterwards.

                    It's very easy to access and remove the jet for cleaning, it's right at the top of the machine when you remove the top cover. Just make sure the machine is unplugged and has cooled down for at least 1-2 hours as there can still be hot water under pressure in the system.

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                    • #12
                      I would undo a water line after the pump, and flow test again. Basically directly out of the pump.
                      that will show if it's pump or a restriction elsewhere.
                      Be aware you are starting to get in pretty deep now. You might need to unplug element if your boiler is low on water, or use a dummy lead to power the pump independently.

                      However, I have had a few cases of restricted restrictors, perhaps split that fitting and check it out.

                      Click image for larger version  Name:	IMG_20190729_105237.jpg Views:	0 Size:	140.4 KB ID:	831628

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                      • #13
                        I’ve disconnected the 3 way solenoid from the inlet and outlet and the restrictor seem to be clear of debris and scale. I cannot disconnect the discharge pipe as the nut is badly rusted and I’m worried I’ll end up damaging the solenoid if I force it further. The piping downward of the solenoid is also clear.

                        I want to test the water flow before the solenoid, Can I run the machine with the solenoid disconnected from the inlet but electrically connected? Looking at the connection downward of the pump, there is nothing else stopping the water from flowing through the HX if the pump is running, is that correct? So if I turn the machine on and the pump engages water will come out of the HX even if the brew button is not pressed?

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