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VBM Domobar Junior brew pressure too high?

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  • #31
    Sounds like the Group could do with a full overhaul service.
    Group overhaul parts kits can be obtained from some of our Site Sponsors or could just take your machine into a reputable service tech (Site Sponsors) and request a full service on the whole machine.

    Mal.

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    • #32
      Yep, need that fixed.
      soon get sick of cleaning coffee grinds off the kitchen

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      • #33
        Does anyone know what could typically stop water/coffee flowing through the drain chamber on a water/detergent backflush?

        I'm getting nothing. I just wonder if there is something common that is worn for that to happen.

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        • #34
          Blocked 3way

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          • #35
            What is the 3 way? Is is the bottom part where the drain chamber is? Or is it in the mushroom cap at the top? I'm in Melbourne, so can't really go get this fixed right now. I'd like to try myself

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            • #36
              Not sure. I forgot it was e61.
              i think the lever on the side pushes a valve open.
              Should be utube videos to show how it all works

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              • #37
                https://youtu.be/1C0VdpfGXhc
                E61 full service

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                • #38
                  Originally posted by anthonypiccolo View Post
                  What is the 3 way? Is is the bottom part where the drain chamber is? Or is it in the mushroom cap at the top? I'm in Melbourne, so can't really go get this fixed right now. I'd like to try myself
                  There are some good diagrams out there of the e61 group. The valve will be back behind the brew head somewhere. Water flows in from the top and down when brewing. When I back flush my Junior it will release pressure when I push the lever back down, but it's not a violent purging... Water just flows out of the bottom of the group into the tray below. There is still some pressure left on the Puck.

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                  • #39
                    Originally posted by GaryM View Post
                    There are some good diagrams out there of the e61 group. The valve will be back behind the brew head somewhere. Water flows in from the top and down when brewing. When I back flush my Junior it will release pressure when I push the lever back down, but it's not a violent purging... Water just flows out of the bottom of the group into the tray below. There is still some pressure left on the Puck.
                    So I think the difference is absolutely no water comes out of the drain chamber when I back flush. No pressure is released so it's all at the puck and the portafilter is literally stuck there and I have to manage the situation to try and avoid an explosion there.... The shower screen has flown off before when trying to get the portafilter out. So there is clearly something wrong there.

                    I wonder if that's what could be impacting the taste / sourness of my shots though.

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                    • #40
                      Originally posted by anthonypiccolo View Post

                      So I think the difference is absolutely no water comes out of the drain chamber when I back flush. No pressure is released so it's all at the puck and the portafilter is literally stuck there and I have to manage the situation to try and avoid an explosion there.... The shower screen has flown off before when trying to get the portafilter out. So there is clearly something wrong there.
                      You have already been provided with the solution

                      Originally posted by level3ninja View Post
                      I wonder if that's what could be impacting the taste / sourness of my shots though.
                      Nope- assuming it's clean and your technique is satisfactory, your machine is likely running cold (or the coffee is poorly roasted). Service time.

                      Originally posted by anthonypiccolo View Post
                      I'm in Melbourne, so can't really go get this fixed right now. I'd like to try myself
                      Not so. A little research will provide info that pickup/dropoff is available in Melbourne under Stage IV restrictions, so you can easily have your machine serviced if you are not inclined to do so yourself.

                      Skimp on service on the Domobar Junior and it bites....wallets. Don't say you weren't told.

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                      • #41
                        So did the E61 full service, all seals looked good, but replaced them anyway, and brand new pistons. Cleaned the mushroom (which was already quite clean) in a bath of descaler and then wire brushed it. Everything looked pretty good.

                        Now when I brew a coffee I can see. the drain chamber drips as the coffee is brewing, is this normal? Obviously before I had 0 drips even when backflushing. Now when I backflushing I see some water dripping through as well. I don't know what would've caused any blocking. However, I do notice when I do a chemical backflush I don't see the espresso cleaner come through the drain chamber which I did a few years ago.

                        Overall, there seems to be some water dripping through the drain chamber now which is good.

                        I spoke to my coffee roaster (Small Batch) - they told me brew pressure for them is around 7 BAR, 95 degrees and 20 in 45 out for 27-30 seconds. So should I try adjusting my brew pressure to around 8 BAR? Seems far too low. Coffee still has sour taste no matter the brand. Maybe I just suck at this, doesn't seem to be anything inherently wrong with the machine

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                        • #42
                          If your brew temperature is not way off, have you tried playing with different grind/yield? I love the science and reading aspect of the hobby, but if it isn’t working, change things up and let you mouth decide. Whenever I roast new beans I always pour 3 basic shots 1:1, 1:1.5, 1:2. Some beans are just more to my taste with a slow ristretto pour than a more traditional espresso pour. I am far from an expert, but my experience with curing sour shots is to slow the pour (grind finer). Pouring 20 grams in and 20 grams out in 45 seconds may not be typical, but if it tastes amazing I am happy.

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                          • #43
                            Can you do a video?

                            Shouldn't be leaking out the drain when making your brew, maybe a seal pinched, or something.

                            Try tasting the brew water without any coffee. Wait till it cools so you can taste it properly. If it's not nice, there no way you can make a good brew.

                            Are you saying your chemical backflush doesn't make froth out the drain? How can that be? Is it maybe backflowing into hx. That would likely give a gross taste after. Lol

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                            • #44
                              Ever since I did the full e61 service, the temperature at the group gets to 105C and when I flush it's far too hot.

                              I think because the group hadn't been serviced it may have been running cold, and that's when I moved boiler pressure up to 1.3 BAR from 1.2 - I guess now that the grouphead is serviced I can move the boiler pressure back down to 1.2

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                              • #45
                                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.

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