BES900 and the brass OPV…

As many of you already know, from early on we had the idea of changing out the plastic OPV for a more heavy duty OPV.

People asked why, my answer to that is 1. because we didn’t feel that the plastic OPV would stand up to the test of time and the ups and downs that we all have when it comes to playing around with our coffee settings, getting chokers, gushers, getting it right.  Yes it may has withstood 10 thousand times in testing but that is at one constant setting not the multiple settings a coffee lover goes through.  As we all know different beans need different settings and we often don’t hit the right setting straight away, I felt that a plastic OPV wouldn’t withstand those sorts of changes for long.

Oh and 2. because we can 😀

Now first off I have to say that this wasn’t an easy changeover, I guess the first time someone does something new there are almost always causalities, in our case it was our pump (more of that later), don’t be alarmed though if done carefully anyone else attempting this shouldn’t have the same trouble.

Normal disclaimer before I go ahead: BE SAFE AROUND ELECTRICITY, UNPLUG BEFORE YOU FIDDLE !!!


I took the covers off the same way that I did for the adjustment, you really do need to take the back cover off to give you more working space and accessibility.

First off here are photos of the original OPV, I’ve joined everything back up just to show you what you are looking at, you can see the threaded section where the OPV screws into the pump.

The original OPV and attachments.

The small section on the far right hand side is the end of the tube that has been cut off to allow for insertion into the new elbow that fits into the brass OPV.

Yes I can hear the questions already, what brass OPV did you use?  Where did you get it from?

We had chosen the new OPV we wanted very very early on during an OPV discussion on the Crema forum.  When it came time to make the final decision I was actually guided by Richard, one of my fellow Crema members who had just changed over his old OPVs in his Expobar.

So there you have the answer to the first question.  The new brass OPV is what Expobar call an expansion valve, part number E614.

Where I brought it was sourced from the same supplier that Richard bought his from, Espressobits in Victoria, I will get in contact with them and check that it is ok to put their details up before I do.

…and here it is…

Unlike the older Expobar OPV this one doesn’t have any plastic in it, a comparison can be seen here, the centre OPV being the most like the one both Richard and myself are using.


I needed to find a new attachment for the small hose that goes to the group, at present it is an airline fitting, I’m hoping to source a better fitting than this, it is only rated to 70 degree Celsius, in knowing what I do about fittings though this would be a constant temperature rating, for the purpose of what we are doing I felt that until we sourced a food grade part this would service.

I do have to say this about the fitting though, it is priced the same as the similar part from Espressobits that fits the Expobar machines, so I’m not sure that theirs would be rated any differently.  Oh why didn’t I buy theirs, well theirs fits a 6mm tube, the BES900 has a 4mm OD tube.


Here I come to the causality of the conversion, our pump.  What we neglected to recognise when first looking at the two OPVs was that the thread on the new OPV is longer than the old OPV and there is a reason for the old OPV having a thread as short as it is…by looking at the above photos of both new and old you can see the differences.

Yahoo we thought, detached the old parts, attached the new parts and off we go.  In the process of adjusting the OPV the pump sounded, well, wrong.  The OPV worked, that wasn’t an issue but the pump definitely didn’t sound like that before the changeover.

After Steve pulling the pump apart, putting it back together, definitely nothing wrong there, we tried again, and again it sounded not right, it was then on closer inspection that Steve figured out what had gone wrong.

The length of the new OPV had engaged and pushed into the top of the valve of the plastic section of the pump and caused the pump to mis-fuction.

After a discussion with my fellow Crema mates and a phone conversation with AM (he really is worth more than all the tea in China) I discovered that the free Breville machine we had picked up a year earlier was going to help us out again, it has exactly the same pump in it.

So out with the old and in with the old and the process began as to what was going to be the best approach to fitting the new thread into the pump thread without hitting the valve.

We tried washers and o-rings of different sorts but nothing was working, it would seal correctly, so finally we came to the conclusion that the end of the thread had to come off.

There are two ways (probably more) that the thread can be taken off, a lathe or a hacksaw and file.  Steve has the access and ability to use a lathe so that is what he did, measured up the plastic thread lenght matched it up with the brass thread length and took off the appropriate amount.

Below is what the brass OPV now looks like.

Also a comparison photo with the old plastic OPV.

Now the fun could really begin, putting everything back together again.

So the parts I used are:

Expobar expansion valve E614

1/8 BSP male to 4mm tube swivel elbow

6-16mm hose clamp

o-ring to fit 1/8 thread

It was then a very simple process of adding the o-ring and thread tape to the thread attaching the OPV to the pump, remembering to attach thread tape in the opposite direction to the direction that you screw the thread in and screwing it in.

Next step attaching the overflow hose back onto the OPV, now using the hose clamp as the hose is actually too large for the OPV attachment and without the new clamp it will leak as it’s not closed tight enough and the small tube to the elbow at the top.

The last thing you need to check for are leaks, please please be careful…

I don’t recommend doing this by yourself if you are not qualified to do it.

Once you have checked for leaks and found none, then comes the fun part of adjusting the OPV, I say fun because it is SO SO SO EASY.

Here you see the adjustment end of the Expobar OPV, a flat head screwdriver or something similar and someone to tell you up or down is all you need.

I’ve adjusted my gauge to sit at 10 bar as I did with the old OPV adjustment, I just find that this suits myself and my ability at this stage.

It took me a few shots to get the grind right, I find that I am grinding finer now than I was before, I also have to say that when I finally got the grind and tamp right (well for the first go anyway) the result was amazing.  I’ve been drinking mycuppa’s roasted Tanzania and have never tasted it like I got tonight, smooth, sweet cocoa as a cappuccino, I also have to say that the bean was roasted over a month ago, who would have thought huh 🙂



24 Responses to BES900 and the brass OPV…

  1. Muscles

    January 23, 2012 at 9:28 AM

    Hi Nic,
    Glad you finally have your machine up and running again!! Can you do a vid of the gaugue during extraction so we can see how the flutter situation is now?

    Also, do youstill have to remove the lid or back panel to adjust the new OPV or did you drill a hole in the case?

    By the way, great job on the write up and nice pics…

  2. Anger

    January 23, 2012 at 9:48 AM

    Nic, if your careful with the opv placement, you could be like the Minore III and have a suitable hole (with a removable plug/cover) that will allow you to tweak without having to remove covers….

    PS. Try a OPV setting that maxes out at about 8.5 to 8.75. I am starting to really enjoy coffee at this sort of group pressure.

  3. Karl

    June 13, 2012 at 4:14 PM

    Like whay you’ve done Nic. Do you think I could do this to my cheaper model sunbeam 4800c ??

  4. Cikay

    November 20, 2012 at 4:43 PM

    Hi Nic,

    Ive been following your first OPV post in order to adjust the OPV on my BES860 and found it to be absolutely spot on. Great writeup! I am currently considering replacing my OPV in my BES860 with a new one as the OPV on the BES860 has limited adjustability (2 loosening revolutions and the adjuster falls off!) I was just wondering if you could perhaps email me the contact for EspressoBits to get this Expobar? And out of curiosity how much did u get the part for? Thanks for your help, and keep up the good work =)

    • Cikay

      November 20, 2012 at 4:44 PM

      Sorry i mean Expobar OPV, and not the entire machine LoL

  5. kym

    November 23, 2012 at 11:35 AM

    Bes900 purchased June 29 started leaking coffee above grouphead in 4-6 weeks, replaced o ring still leaking, I requested a new machine no luck they want to fix it, any idea the problem….

  6. Nathan

    January 13, 2013 at 11:50 PM

    I’ve checked all around Expobar’s sites and parts providers, and there is no Expansion Valve model E614 that I can find. Where did you get this from? Is there a web page I can order from–Many of the Expansion Valves I could find for Expobar machines lacked pictures, or I would have attempted to match to your photos.

    • Nic

      March 20, 2013 at 11:32 PM

      Hi Nathan, did you ever find the OPV? I’ll find my information and put it into a blog post as there seems to be drama after drama with the OPVs even with Breville having them redesigned a few times.

  7. Ino

    May 16, 2013 at 8:51 PM

    Hey Nic – I got the OPV from the Espresso bits and it was very very easy to deal with them.

    However – my question is – where did you get the BSP-to-push-in tube adaptor? Who sells that kind of stuff around?

    I know Camozzi makes them – but finding a distributor around here proves to be more than difficult.



    • Nic

      May 27, 2013 at 11:14 PM

      Hi Ino, sorry for the delay, I got the BSP adaptor from Blackwoods here in Australia, they are an industrial supply place. I was hoping to get a food grade one but they were really expensive for what they are so I thought I’d try just a normal stainless steel one at a tenth of the price. The thinking is that it’s only water going through it so there shouldn’t be any problems BUT it is up to the individual what they feel more comfortable with.

      • Ino

        June 10, 2013 at 7:41 PM

        Thanks Nic – I actually went for a food-grade adaptor made by Parker – and I went for the straight stub – no right angle in it. It’s made of bronze, with food-grade nickel plating. I’ve asked for the ones made to withstand 20 bar.

        Super easy to install, plumbers taped it and tightened it from inside – it’s got an Allan-key section on the inside.

        I’ve yet to install the valve though – I’m away for a month and to tell you the truth – I’m already missing my good coffee! 🙂 I’ve been downgraded to old Aldi pre-ground plunger coffee! Euuurgh! I have to up the dosage to get a good kick! Dregs (a-plenty) make a good fertiliser – all the little shrubs around the door are sporting wood 😛


  8. Brendon

    November 17, 2013 at 4:30 PM

    Hi All,

    I stumbled onto this site googling for help with a low flow rate problem with my BDB. Seems like there are a number of people active in the comments who are knowledgeable of the inner workings of the machine. I figured I’d just take a shot in the dark and see if anyone has had this problem or has suggestions for what to try.

    The problem is that the flow rate coming through the grouphead is abnormally low, maybe 1/3 to 1/2 of what used to come out. This is without the portafilter in place. The steamwand and hot water dispenser seem to be functioning normally. I’ve tried taking apart the accessible parts of the grouphead and cleaning them, as well as a cleaning tablet, both to no avail.


    • Nic

      November 24, 2013 at 12:40 AM

      Hi Brendon

      You might also want to have a look at the thread on Coffeesnobs, here.

      I haven’t had many issues with mine, I don’t know if that is because we replaced the OPV very early on or just because I look after my machine well or I just got lucky.

      One of the other guys might see your comment and have an answer for you.

  9. Ki

    February 13, 2014 at 11:54 AM

    My OPV snapped (or busted???) into 2 pieces after 8K run.
    Should I MOD the machine or order original part from Breville? Also where can I get the parts? Thanks.

    • Nic

      February 21, 2014 at 2:37 PM

      Hi, sorry about the delay in replying, have you fixed this? Are you in Australia?

  10. Tina

    September 7, 2014 at 12:33 PM

    Did you manage to find a better fitting for the small hose?

    • Nic

      September 22, 2014 at 11:27 PM

      Hi Tina, the service centre still haven’t got back to me, I’m going to try again, if not I’ll give Breville a call and see if they can help me. I needed to adjust the OPV the other day and had a look at it again and it now has little sticky bumps in places, it’s definitely time to replace it.

  11. Yousif

    September 22, 2014 at 10:42 PM

    Hi there. This is very informative and made me decide not to upgrade to a new machine but to upgrade my current machine. The trouble is I cannot find where to buy this valve from. I live in New Zealand. Does the valve go by another name or number?

    Many thanks, Yousif

    • Nic

      September 22, 2014 at 11:47 PM

      Hi, this valve is specific to Expobar, it just happened to fit the Breville as well.

      You could try Clinton from Espressobits, where I got mine from, email – That was in January 2012 so I’m unsure if it’s still current.

      • Johnny Tseng

        January 3, 2015 at 1:53 PM

        Hello Nic,
        I am attempting the brass OPV upgrade on my BDB now. It seems like turning the OPV to unscrew the original nylon one or screw in the new brass one, the OPV horizontal member will hit the chassis of the BDB as you turn. Do I need to remove the nylon riser below from the pump to be able to remove and install OPV. Your steps did not indicate the need. Am I missing something in the process?
        Thank you,
        Johnny Tseng

  12. Johnny Tseng

    April 5, 2015 at 4:31 PM

    Hi Nic,
    Thanks to your inspirational article, my BES900XL also has been upgraded with the Expobar OPV now. I feel the machine works the way it should with the brass OPV. The plastic one was just junk. My BDB is now not doing the 1shot 2shot volumetric function. It does not stop any more. Any idea about what I need to do?

    • Nic

      May 15, 2015 at 4:12 PM

      Hi Johnny
      Glad I could help, good to hear you got everything working correctly with you OPV upgrade.
      The volumetric buttons have never really worked consistently for anyone, the software updates might have fixed the problem but since I voided my warranty as soon as I got it I’ve never taken it to a service centre, it’s never needed to go to a service centre for anything anyway. I think majority of the people I know have never even used them except when they first got the machine and played around with it.
      I’ve seen comments on forums from people that have taken their machines to service centres to see if they can fix them but even then it hasn’t worked.
      I can only suggest getting on to forums and seeing if it’s something anyone else has been able to solve.

  13. Vincent

    April 11, 2015 at 12:16 PM

    Hi, great site, and excellent detailed explanation of the mod. I am just curious, is your breville still going strong with the opv mod?


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