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VBM Domobar Junior brew pressure too high?

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  • #46
    Originally posted by roosterben View Post
    Re the drip from group and backflush not working normally, did you check that each E61 valve was specific for VBM Domobar Junior. The E61 group is a general design but each manufacturer has slightly different implementations. So if you bought a CoffeeParts E61 kit, not all the components will work in every E61 machine. If you have chucked out the old valves, pull the group apart and put each valve side by side with the old ones and make sure they are 100% identical. Other possibilty is springs in the wrong spot or valves upside down.
    Yep, I bought it from Talk Coffee and got the specific VBM parts.

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    • roosterben
      roosterben commented
      Editing a comment
      Well if it is dripping while making coffee and not backflushing properly you either put it together wrong or a part is not right.

  • #47
    It's weird, after replacing the pistons with brand new ones with new gaskets, when I backflush and put the brew lever back down, I still don't get that pressure release and water exiting the drain chamber, I remember it would almost squirt out as the pressure was released. I read this online. Perhaps it's something to do with this as I have a brand new 3 way valve in my E61...

    Also in response to your comment @roosterbean - I'm sure the few drops leaking every now and then is probably because I potentially put a valve incorrectly, but I don't think I did. But the backflushing issue has persisted before I replaced these parts and continues to.

    Could it be the operating cam is worn down and therefore it never engages properly to allow the water to go through the drain chamber to begin with and open those valves?

    My group head won't flush when I put the lever down
    • Move the lever up and down and see if resistance is felt in any direction from the cam moving between actuators (valves). If it will not drain, and not much resistance is felt, remove the bottom of the E61 group head and inspect the actuators. They may be broken, or ground down from poor maintenance that the cam does not make contact with the top of the actuator.
    • Remove cam and inspect for flat spots. If the cam is ground down it may not be making contact with the actuator.

    Comment


    • roosterben
      roosterben commented
      Editing a comment
      When I had the some problem in my Rocket Giotto I bought a new 2 way solenoid (still sitting in my parts box as it wasn't the problem). After pulling apart the group a few times and checking each item against the old and re-assembling exactly to the parts diagram it started flushing correctly (as below I may have had to reposition the lever handle/cam but can't remember).

      Your lever if you pulled it off and replaced the o-rings and cam when you rebuilt your group, maybe you reassembled at a different position so it is not moving the E61 valves correctly which is causing a) Drips from not sealing properly and b) Not flushing properly from the backflush due to the lever handle or cam being out of position.

      When checking the lever I find it easy if you have removed the top nut on the E61 group to loosen the top spring with the mushroom. Then is it easy to check the position of the lever cam and make sure you have attached the lever handle in the correct position.

      Per your above comments you can easily remove the lever cam and have a look at it.

  • #48
    Hi, 4 weeks ago you first posted your problem with the VBM, numerous posts, suggestions, ideas to fix etc the problem still exists. Time to call in the cavalry and find an experienced espresso tech to sort your machine out.
    I would well and truly be having serious caffeine withdrawal symptoms by now.
    Maurice

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    • #49
      Hey all,

      I just thought I'd follow up on how things have progressed.

      - Grinder was recalibrated
      - Added coffee sensor, ensuring I was brewing at 92-95 degrees. A flush before brewing for around 8 seconds will usually get the grouphead to ~91C so I'm assuming at the puck it would be. around ~93-94. Didn't seem to be a temperature issue though
      - E61 grouphead completely taken apart, cleaned and new pistons added. After doing this the backflush was still not coming through the exit chamber.
      - Added a new cam lever which completely fixed the above issue.
      - Lowered the brew pressure to 9.5 BAR

      After all of this still getting source / not nice tasting coffee.

      I spoke to. my roaster Small Batch about it and they confirmed I had the right recipe, 1:2 in 27-30 seconds. They said they think my brew pressure was way too. high, they told me they bre at around 7-8 BAR. I thought that was way too low based on everything I've read here, but last night I gave it a shot.

      Once I lowered to 8, the first shot I pulled tasted so much better.

      Why does brew pressure impact the taste of coffee so much?

      Also, I'm really glad I've been able to fix the grouphead with the drain chamber functioning perfectly again.

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