quattrocchi wrote:I'll contact the servicing agent and ask how they actually check the pump pressure. It was checked OK in late Jan and I noted then the gauge read 12. Ah, now I've found the job sheet:

19.1.2010 "Dismantled head unit cleaned out lime scale and coffee buildup replacing worn valves x3 and head gasket and screen and lever seals. Replaced worn steam and hot water valve seals and steam wand. Replaced faulty electronics and worn expansion valve seal. Descaled boiler level probe. Adjusted pump pressure, tested ok and (tagged?)."
1 fa516528/n head gasket 10.15 NZD
1 fa526100/a diffusion screen 12.29
1 vb/assvalvrog distribution valve 18.56
1 vb/assvalvinf infusion valve 25.78
1 vb/assvalvscar discharge valve 19.09
2 vb/guarpica lever rod seal 7.04 ea
3 vb/guarsilrudom steam valve seal - silicone 6.50 ea
1 vb/tubivadomsu steam wand - Dom 52.75 (we wore through to the brass!)
1 vb/eletregliv RL30 electronics GICAR 128.07 (the main reason we put it in)

Thanks for the continuing comments. Maybe they tested the pump pressure as ok at the puck but the pressure gauge is 'optimistic'. Since so many seals were replaced in January I feel more confident disassembling the group head for a clean-out. I see how erics took apart the mushroom area Checking an E61 Espresso Machine for Scale but would like to see a page on removing the lower parts, the drain bits.

My first thought to the 1st post was worn valves. Having seen the parts list above it could be the replacement parts are out of tolerence. The original "E61" group has many modern replicas and they all use slightly different parts and from different manufacturers.

Those gauges are ridiculous, never mind the acetone, I think they used sandpaper to clean them.

Paul

I disassembled the group and was amazed at how easy it was! Thanks people for all the information and encouragement. What I found was a crusted-up mushroom, wear on the cam and the followers, and a grubby lever pivot.



I fashioned a scraping tool from a 3mm copper rod and the scale bits come off quite easily. Copper was a help also in undoing the large nut in the drain assembly, as I don't have a spanner big enough. I used a pipe wrench carefully with a strip of 0.7mm copper sheet placed over the nut. I'm a jeweller so I have bits of copper and silver lying around.

Not a lot of coffee residue - none I could see - but after reassembly the whole action now is so smooth! I'm going to get me some lubrication.

stefano65 wrote:Well not to speculate here
but looking at the way the machine is NOT clean I will assume that the grouphead is so gummed up inside that prevents the opening of the discharge valve
regarding the OPV follow the above suggestions and lower it down
that when you are backflushing ( after you rebuild the group and clean it)
will open at 9-10 bar

I've had the group apart a few times since the last time I posted here in this thread, and can report that the inside of the group head and the three way valve was NOT gummed up, just a bit scaled up around the mushroom. And it's still intermittently failing to discharge pressure via the three way valve after a shot.

Maintenance: I do a blind flush, water only, morning and afternoon after each session. I clean the PF with pulycaf weekly, and backflush with cleaner about fortnightly.

But pressure often (not always) stays in the portafilter (drips coffee after the lever's been put down) after a shot. Today I tried this: after a shot, with pressure in the portafilter and the handle rather tough to undo, I made a rapid up-down lever movement. That caused a whoosh out the three way valve and the PF was easy to remove.

I can't understand what might be causing the three-way-valve assemble to stick in the closed position after the lever's returned to rest position. Maybe the pre-infusion valve seal is sticking closed! That's the one directly under the cam, on the top of the 3-way valve, which has a weaker spring and is designed to allow some lowered-pressure water into the PF. A clue: when pulling a shot the pressure will either rise slowly and steadily up to full pressure or it will get to about 3/4 pressure then ZOOM up to high pressure. I wonder if this rapid pressure build-up shows the pre-infusion valve is stuck closed.

The valve seals don't look new anymore. I'll post pictures when I can. Heres the mushroom valve seal, taken after a de-scale of the mushroom.



Re the OPV the agents here Espresso Engineers, Auckland insist that the pump pressure should read high in order to get 9bar at the PF. I believe them as they have had much development input on this VBM and their improved specs were agreed-to by Vibiemme. It may not be the same unit you have there in the US.

Brian

I can't understand what might be causing the three-way-valve assemble to stick in the closed position after the lever's returned to rest position. Maybe the pre-infusion valve seal is sticking closed!

The wearing surface of NEW "pins" which come into contact with the operating cam certainly appear flat but, very much like older automotive engine lifters which get moved by the engine cam(s), these surfaces have a spherical surface. This spherical surface (or let's just say not flat) induces a very small rotation to the pins when they are asked to move. This promotes even wear.

Your preinfusion valve pin or cam or both has some unusual wear or, as Paul P. previously said, some out of tolerance parts may have been installed. The preinfusion valve cannot "stick closed" when the lever is in the exhaust position because it is mechanically forced open. If you want to provide overall length dimensions on all three pins, I'll be happy to compare with some I have.



Re the OPV setting on your Vibiemme, your Espresso Engineers are incorrect in setting the pressure that high. What Stefano previously recommended is correct based on lots of readings I did a couple of years ago. Yes, these espresso machine gages are not too accurate but setting the valve such that you read 9-10 bar with a blind filter will make you and your machine happy.

I've fixed it! Our machine now drains with a good health WHOOSH!

Here are my three valves - the basic measurements (they do have flat mating surfaces where they meet the cam):


The drain valve, in particular was total length 26.9mm:


I figured out that the drain valve was not getting much action from the lever cam. In fact it barely moved when the lever is in the down position. I tested this by putting everythong back together except for the drain valve, placing it lightly up into the cavity, and working the lever. Hardly any movement! Either the infusion valve or the drain valve is too short!

So I unscrewed the drain valve:


... and refitted it together but left it a few turns shy of done up tight.
Drain valve after lengthening by 0.5mm approx to 27.5mm:


Great to have the problem diagnosed (substandard parts fitted) and temporarily cured. I'll contact Espresso Engineers for a comment. Thanks all.

Here are mine:



MM dimensions for valves, top to bottom are:

Brew: 54.84
PreInfusion: 61.06
Exhaust: 26.98

edit - substituted improved drawing - springs are a little tough to measure

Thanks.
Comparison of your parts with (mine):
Brew: 54.84 (53.9)
PreInfusion: 61.06 (60.7)
Exhaust: 26.98 (26.9)

PreInfusion PLUS exhaust: 88.04
Mine: 87.6 shorter by 0.44mm.
Lengthening my exhaust valve (by unscrewing it 0.6mm) makes it work better.

WRT the brew valve, length is not so important. It's the distance from the seal to the cam.

Lengthing my exhaust valve by 0.6mm makes it work better.

FOR NOW, lengthen the part by adding another small washer (or two), NOT by leaving the pin loose. The New Zealand company MAY be able to obtain design lengths from Vibiemme and, of course, there's always cam dimensions to compare.

The operating cam moves the preinfusion valve 0.1123" (2.85 mm). After taking up the clearance, this moves the exhaust valve 0.0433" (1.10 mm).

It's a very tight thread, so I felt ok about the full force (against the discharge spring) going on the threads. I'll put in a 0.5mm washer as a permanent solution i my agents here can't supply better fitting parts.