# E61 pre-infusion chamber drain



## rmat (Aug 25, 2012)

My e61 machine has been giving me poor espresso lately and I decided to clean the group head.

One thing I noticed was that the pre-infusion chamber had a lot of muck at the bottom. It seems only the liquid above the top of the spring guide was getting drained, hence leaving a 1/2" layer of molykote coffee funk to mix in with the next shot!

Since these guides are cheap, I've decided to make grooves in it to allow the chamber to more fully drain so as to allow more time between dis-assembly and cleaning in the future.

Has anyone come across this?



http://imgur.com/diO0O


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## garydyke1 (Mar 9, 2011)

Had a good look round mine when doing a full descale a few months ago. Cant say mine had this issue but there was certainly evidence of minor green-coloured scale starting to form, hence I soaked the whole thing in citric acid solution.


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## rmat (Aug 25, 2012)

.. with added 3mm holes so hopefully no more cesspit - and it backflushes like a rocket now!


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## espressotechno (Apr 11, 2011)

Is the E61 head lever action or solenoid valve ?


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## rmat (Aug 25, 2012)

It's an e61 lever. I don't think solenoid groups have pre-infusion chambers, but use line pressure instead.


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## espressotechno (Apr 11, 2011)

Some E61 solenoid heads have pre-infusion (springs & pistons) eg La Scala Carmen, Brasilia Gradisca.

The upper market commercial machines now use electronics to achieve a pre-infusion time, by stop/starting the pump & solenoid valve for a few seconds.....


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## rmat (Aug 25, 2012)

espressotechno said:


> Some E61 solenoid heads have pre-infusion (springs & pistons) eg La Scala Carmen, Brasilia Gradisca.
> 
> The upper market commercial machines now use electronics to achieve a pre-infusion time, by stop/starting the pump & solenoid valve for a few seconds.....


There's a thread comparing both types of infusion here: http://www.baristaexchange.com/forum/topics/is-preinfusion-really


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## dan1502 (Sep 8, 2012)

I'm wondering what's wrong with mine at the moment. I serviced the group head with a kit from Bella Barista not that long ago (probably 18 months at a guess). Anyway, quite a bit of pressure remains in the group after moving the lever right down even when lifting it not quite all the way up then down again, a little remains. Is this normal and if not what should I do about it? It's an expobar leva twin boiler - the pre PID model.


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## rmat (Aug 25, 2012)

That group head service kit from BB looks like a good deal. Anyway, it sounds like the spring in the pre-infusion chamber is too strong - did you put the weaker one in there?


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## dan1502 (Sep 8, 2012)

I think I will have just put the spring that came with the kit in but am pretty sure I still have all the bits that I took out so could swap them. It was a while back but I think they looked the same.


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## rmat (Aug 25, 2012)

Reading your post again, I'm not quite sure what you mean by "pressure remains in the group". Could you describe what indications there are for this.


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## dan1502 (Sep 8, 2012)

Yes, after making the shot and moving the handle right down the pressure gauge remains at a high pressure and the flush is more of a dribble. It tends to be better when flushing with a blind filter though. To get the pressure to go I then have to lift the handle to a point fractionally before the motor is siwtched on. Just another quick question while I'm at it. I just reduced the pressure with the blind filter fitted to exactly 9 bar on the gauge. Whilst pulling a shot the reading was fractionally over 8 bar. Is this ok or a bit too low?


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## rmat (Aug 25, 2012)

Your pressure problem sounds exactly like the one I described earlier - clogged infusion chamber. When taking it out did you notice a bunch of gunk/liquid at the bottom?

re: group pressure, it's ~9 bar at the puck. given the pressure 'leak' through the coffee then, one adds ~1 bar when setting with a blind pf. of course the final setting one uses is the one that produces the best coffee for them - http://www.home-barista.com/tips/effects-of-brew-pressure-on-taste-of-espresso-t17658.html


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## dan1502 (Sep 8, 2012)

I thought it might be the same problem, hence me originally asking in this thread. I might try your modification at some point. It looks like I should increase the pressure a little then. That said I'm only using the built in gauge so it's probably not accurate anyway.


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## rmat (Aug 25, 2012)

dan1502 said:


> That said I'm only using the built in gauge so it's probably not accurate anyway.


I bought a decent pressure gauge for my pf for http://www.flowfitonline.com/acatalog/Online_Catalogue_HYDRAULIC_63MM_BASE_ENTRY_7.html

remember they measure best in the centre 1/3 of their scale


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## dan1502 (Sep 8, 2012)

I just set it so it's 9 bar on the built in gauge when pulling a shot (just under 10 with a blind filter). How did you attach that gauge - a modified portafilter?


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## rmat (Aug 25, 2012)

dan1502 said:


> How did you attach that gauge - a modified portafilter?


like this:


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## dan1502 (Sep 8, 2012)

Thanks. Simple enough and I have a spare portafilter.


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## rmat (Aug 25, 2012)

There is a person here selling a pressure gauge attached to a blanking plate so you'd have two uses for a bottomless pf, IF the gauge is small enough to drop through it. (I made my own bottomless pf with a hole saw - not easy but works fine)

http://coffeeforums.co.uk/showthread.php?7191-Pressure-Measurement-naked-filter-basket

Gauges with glycerin-damped needles are much better for this application though. Good luck!


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## dan1502 (Sep 8, 2012)

I already have a bottomless pf (possibly two) so that would be an option. The question is do I make one myself or buy one of those.... They look pretty easy to make. I'd just need to get the right fittings (and possibly gaskets for that design).


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## dan1502 (Sep 8, 2012)

I'm thinking that as I always use my bottomless porterfilter and have another portafilter (with a single spout attached) I would probably prefer to use that and therefore go with your design. Maybe it's just that I like the gauge to be the right way up. Do you think the gauge being a little further away due to the L piece makes any discernable difference?


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## rmat (Aug 25, 2012)

dan1502 said:


> I'm thinking that as I always use my bottomless porterfilter and have another portafilter (with a single spout attached) I would probably prefer to use that and therefore go with your design. Maybe it's just that I like the gauge to be the right way up. Do you think the gauge being a little further away due to the L piece makes any discernable difference?


The added volume might account for a ~2 seconds to reach the same pressure - negligible when setting OPV pressure. Vibe pumps usually cause needle judder in un-damped gauges.


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## dan1502 (Sep 8, 2012)

Ok, I think I'll go for it. Thanks again.


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## dan1502 (Sep 8, 2012)

Ok, just a quick update. I've just made one. The pressure at the built-in gauge was reading very slightly over 9.5 bar and the guage I have built reads dead on 8.5 bar. So presumably I should aim for this to read 9 bar or are you saying it should be 10 bar to allow for 1 bar due to pressure leaking through the coffee?


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## dan1502 (Sep 8, 2012)

I just found this:

http://www.home-barista.com/espresso-machines/building-portafilter-pressure-gauge-t4254.html

It seems a needle valve should really be added to simulate flow. It looks like I might need to buy a T-Piece and needle valve. And there was me thinking that was easy!


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## rmat (Aug 25, 2012)

That's overkill. Just set the machine to 10 bar from the pf/gauge combination for a start. You can then check your machine's gauge by using a blanking plate on a portafilter and comparing the two readings. (Don't try to 'fix' the machine's gauge like I did)

The next step is to check temperature at the group head. You can do this using the blind portafilter and a thermocouple. If you'd like me to upload a photo let me know.


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## dan1502 (Sep 8, 2012)

Ok, thanks. I actually set it to 9.5 bar but will increase it a little. I'm back to getting fast flow again but will worry about that later. I increased the steam boiler pressure up to about 1.3 bar whilst I was at it which is a nice improvement. Regarding the thermocouple, presumably that will allow me to set the temperature control offset (non-pid digital) accurately. Is this going to be expensive? A photo/details of parts would be very helpful.


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## rmat (Aug 25, 2012)

my setup was ~£12


http://imgur.com/a


it helps to measure water temp using the same procedure/timings as when making a coffee


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## dan1502 (Sep 8, 2012)

Thanks. So am I right in thinking you would put the basket over the top and make a coffee whilst checking? and what about the meter? Do you have a link to what you bought?


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## rmat (Aug 25, 2012)

dan1502 said:


> Thanks. So am I right in thinking you would put the basket over the top and make a coffee whilst checking? and what about the meter? Do you have a link to what you bought?


no, it's ready to go as is. the last image in the previous link has a source url for a meter/tc on ebay. I actually use a Victor86b multimeter so can't vouch for the one on ebay. I can say that the thermocouple on the 86b stopped working soon after I started using it so I bought a cheap chinese tc which works ok.


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## dan1502 (Sep 8, 2012)

So I finally got around to servicing the grouphead again. The handle seemed to have some play and was starting to 'grind a bit'.

As a result having spotted an E61 grouphead kit with new brass parts on ebay for between £20 and £30 I thought I'd get one. That way I could replace any worn parts. The listing was just for the metal parts and was out of stock so whilst waiting for more stock to come in I ordered a kit with the gaskets and springs from Bella Barista. The other kit came back in stock but this time was for about £40 and included the gaskets and springs. I bought one but have not found that most parts differ slightly from my Expobar Office Dual Boiler parts.

I also thought I needed to replace the anti-vacuum valve as it was hissing and as they were about £5 I bought one from Bella Barista.

I thought I would descale at the same time. As this can be a nightmare I removed the anti-vacuum valve from the steam boiler. I then found I could take it apart and clean it and it was then fine. However it was useful as I then removed the fitting to the pressure gauge from the brew boiler (care not to bend the pipe) and using a another step down fitting I had from the pressure gauge I made, used the vacuum valve to block this rather than refit the gauge whislt descaling as I didn't want to keep refitting the gauge. I then used a funnel to fill the boilers with citric acid solution and a siphon and seringe to drain. Flushing the citric acid out was far easier this way but although I have descaled before I was shocked by just how many flecks of chrome there were especially in the brew boiler. I must have flushed about a buckef of water in and out and there were still some left (but minimal).

Anyway, I cleaned all the parts then refitted. Stupidly as it had been a long day I forgot which little square cross section (the bits which are pushed by the cam) goes on which bit. Looking here suggests that the longer one goes on the pre-infusion (lower) one. When I measured those fitted to the kit I bought but did not use, this confirmed it. http://coffeetime.wikidot.com/e61-lubrication

So I tested it and it was much better but the exhaust was still a bit weak. I thought I might do the mod but having only one part if I wanted to retian the full replacement kit to sell or return I didn't want to mess with my original one. At this point I wasn't certain whether I'd put the correct length bits in the right places as described above so this morning I checked. I offered the old parts up with the new to be sure. I had fitted them correctly. Though not a lot, there was some wear to the lower one. I thought I'd try adding another small washer to space this up a bit. I also noticed that even with the added washer, if tightened fully it squashed the gasket sufficiently enough to make the length shorter than the new one. Maybe this is why threadlock is used? i.e. so it can be adjusted and held in position. So I tightened it just enough to exactly match the new one. The result - much stronger flushes.

One thing I notice though which may be completely normal. If I pull a shot (I tested this with the portafilter gauge) moving the leaver back down exhausts quite forcefull now such that the portafilter gauge reads zero. However the pressure on the machine gauge remains quite high. In order to release that I have to lift the handle to a point just before the pump starts then down again to vent. Is this normal? I'm guessing so.


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## DavecUK (Aug 6, 2013)

dan1502 said:


> One thing I notice though which may be completely normal. If I pull a shot (I tested this with the portafilter gauge) moving the leaver back down exhausts quite forcefull now such that the portafilter gauge reads zero. However the pressure on the machine gauge remains quite high. In order to release that I have to lift the handle to a point just before the pump starts then down again to vent. Is this normal? I'm guessing so.


It's normal and caused by the expansion of colder water as it heats....which is also a factor in getting the correct pressure reading from a portafiler pressure guage and not setting the machine incorrectly....a common mistake. edit: what I mean is people often use a pressure measuring portafilter and get the pressure wrong. e.g. in an E61, lever group, theres a rise and pause (preinfusion chamber), *then a rise and pause (correct pressure)*, then a gradual rise of 1 or 2 bar more (water expansion)


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