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La Cimbali Junior M21 Ulka Pump replacement and descale process

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  • La Cimbali Junior M21 Ulka Pump replacement and descale process

    Hi

    My La Cimbali Junior (i.e. water tank version) is around 10 years old and the Ulka EX5 pump is making a loud noise when water is run through or when making a shot, but it quiets down when pressure builds up during backflushing of the machine. It's still pumping water through and making coffee but the noise is getting louder. I have pushed water through the machine under pressure with a syringe to make sure there's no air trapped in the pump but it didn't make any difference.

    I have a new Ulka EX5 pump and rubber mounts and am wondering if it is a fairly simple job to replace the pump that I could do myself. If so, I would appreciate some advice on the steps,

    Also, I have a Ranchio Silvia which I have descaled using citric acid in the water tank and flushing through and letting it sit inside the machine for 20 minutes and repeating this process a couple of time and then running a few litres of fresh water through the machine to clean the citric acid out. My question is,can I descale my La Cimbali Junior using the same descaling process with citric acid in the water tank. Again, some advice on the steps to undertake this would be appreciated.

    Thanks for your assistance,

    Graham

  • #2
    These machines are large and have heaps of room and are pretty easy to work on.

    I have replaced heating elements in at least one and fixed another with seized rotary pump and/or solenoids.

    This may not be the same model but there is a parts diagram here;

    https://coffeesnobs.com.au/forum/equ...-parts-diagram

    If you are competent enough to pump water through with a syringe you shouldn't have much trouble swapping out a pump.

    Just make sure you work with the machine off and unplugged at the mains and not heated up or pressurized. Then be careful unscrewing and refitting the brass fitting from the water out end of the pump (the rubber hose is the inlet side).

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    • #3
      Thanks Ben.

      I assume I should put some thread seal like Loctite on the brass fittings when reassembling to stop any leaks?

      Have you ever descaled a Junior M21 or know if the process I described above is ok to use in this machine?

      Thanks

      Graham

      Comment


      • roosterben
        roosterben commented
        Editing a comment
        Generally no tape or Loctite is required I just hand tighten by feel until leaks stop. On the pump brass outlet there is a flat bit where a spanner will fit (12mm maybe but can't recall) then you grip the other fitting with another spanner (or even just hand tighten. You do need to be careful as the brass elbow fitting from machine can get brittle from heat and age.

        Test machine with case off and ensure no leaks before putting case on. Tighten gently bit by bit to stop leak.

    • #4
      Hi Ben

      Thanks for your advice. I have replaced the Ulka pump with a new EX5 Ulka, same as original, and checked for leaks, Didn't have any so put the case on. It is definitely quieter that before and no longer makes the rattling/buzzing sound. However, the new pump is noisier that when the machine was new.

      Have checked and nothing is touching anywhere and ran some water under pressure with a syringe through the pump when machine running to make sure no air in pump. I know vibration pumps aren't the quietest, and just wondering if it's the case that some Ulka pumps are quieter than others. Appreciate your thoughts.

      Cheers

      Graham

      Comment


      • #5
        Well I have managed to make the new pump quieter when running water through it with no pressure on the pump. Found the pump's outlet stainless steel hose's rubber insulation had worn through and so the stainless steel hose was touching the coffee machine's steel frame and was making a noise from the pump's vibration. I placed some rubber between the hose and the frame and it's a lot quieter.

        However, with my old pump when back flushing the brew head with a blind filter or running a shot, my old pump went very quiet, whereas my new pump gets louder. I'm wondering if the new pump's noisier when running a shot or back flushing because its building up more pressure than my old pump. Does that seem like a reasonable explanation? Thanks.

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