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Cannot get high brew pressure anymore - HX e61

Postby GriffDeLaGriff on Mon Dec 31, 2012 7:54 am

Basically, I can't seem to get more then 9.8 bar on my machine, and I will tell you why this is a problem, and perhaps someone knows whats wrong.

The story is - I had alot of channeling at home but didnt see this on other machines as much so someone said check the pressure. I dont have a pressure gauge on my machine (La Nuova Era Cuadra) so I built one.

It showed 13.5 bar so I adjusted the OPV as much as I could and it gave me about 11 bar and that was the end of adjustment so I was happy there and got pretty ok espresso. There came more water in the driptray of course, but it was ok and I just enjoyed the coffee.

After a "long" time I noticed how the driptray got almost full in a very short time so I immediately thought of the OPV. At this point I was gonna be ok with getting a little higher pressure back if it meant not so much water in the driptray. The problem was that the OPV was stuck and I tried to get it out with all my might and it broke. The key just went round and round.

So I ordered a new one (along with a new set of burrs for the M5).

I got it, installed it, and checked the pressure and it was only about 8 bar. I tried and screw it back and forth but couldnt get a high pressure like before. So I put back the old OPV (which should give me about 11bar) but it gave the same low reading. So I put the new back in and measured from the very ends of adjustment (from all the way in to all the out) in increments of 180 turns (and even 90 in the "sweet spot") and my absolutely maximum is 9.8 bar.

If it holds here for years then everything will be fine since it will give me about 9 bar with coffee, but I feel like something is odd.

So my question is: does a vibe pump have an expiration date? Have I used it up? I cant remember but I think I got it about 5 - 7 years ago.

There is no leaking.
Everything works - steam and making shots as usual.
I use the same measure gauge as I did before - without a portafilter attached. I cant get it 100% tight so there is some water sipping out while I measure - about the same as an espresso, exactly as the last high measure before all this.

The exact things I have done:
1. Changed the 3-way plastic connector to a metal one from chris coffee (because the plastic one crumbled)
2. Changed the OPV to a new one exactly the same.
3. Changed the quick fitting from the t-connector under the OPV to a new one (its a little different but I cant see how this should affect anything.
4. Cut the teflon pipe into the quick fitting maybe 1cm.

I think your first question is - how is the coffee? Well Im out of coffee and its closed for the holidays so I will get back to you about this, but still, any ideas about the pressure?
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Postby GriffDeLaGriff on Mon Dec 31, 2012 1:40 pm

Got my beans today! woho!

The shot looks and tastes right. Normal crema.

Tried a naked extraction and it seemed easier to get no channeling, but I dont know if its due to pressure, new burrs, improved technique - or a combination of all. :mrgreen:

I still wonder of course what makes the machine not able to produce higher pressure.......not that I need it, but something definitely happened.... :?:
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"...if the puck's surface looks and feels basically the same each time, I believe you've exhausted the value of 'puckology.'" --Dan Kehn, Wet Pucks

Postby allon on Tue Jan 01, 2013 10:20 am

Vibe pumps do have seals in them that will eventually fail. They cannot be rebuilt, for the most part, because replacement parts are not available, but that doesn't mean one cannot try.

However if it works for the time being, leave it. Vibe pump repair is a last ditch effort and there is a risk of damaging things further.

Repairing a ULKA vibratory pump

Rebuild Kits or Source For Ulka EP5 Pump Parts?
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Postby GriffDeLaGriff on Tue Jan 01, 2013 1:13 pm

It says in one of the links that a whole pump is only about $60.
Thats nothing compared to a new machine.

But yes I will leave it for now, its actually easier to make espressos, there has been no spritses or anything from my naked pf it just flows really nice. The pucks also looks alot smoother without holes in them.

BUT - could something really be used up in only about 5 years? Is this the most reasonable explanation?
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Postby cannonfodder on Wed Jan 02, 2013 11:11 am

It is odd that your machine's OPV dumps into the drip tray. They normally run back to the water reservoir. On a plumbed in machine there will be an emergency pressure vent that dump to the drip tray just in case you get a failure in the rotary pump or the sealed hydraulic system spikes above about 11 bar. Then it would open and drip into the drip tray until the excessive static pressure is released but it should not spit water while you are brewing. With a vibe pump, the OPV return normally goes back to the water reservoir and will have water flowing out of it during a shot. A vibe pump puts out 12ish bars of pressure and the OPV is simply a spring and ball valve that cracks open to vent the excessive pressure to keep your group pressure at the desired level.

Luck of the draw on longevity of a vibe pump, some run for a very long time while others may burn out in a few years. Vibe pumps are also susceptible to power fluxuations. If you are dropping voltage at the machine the vibe pump will lose power and drop pressure.
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Postby GriffDeLaGriff on Wed Jan 02, 2013 11:50 am

Yeah ok.

Well on this model the excess from the OPV actually goes into the driptray.
I saw a mod to make it go into the reservoar, and its easily done. (just reroute the plastic tube)

However normally its not that much and I like to see it specially now to have some sort of "control" or supervision of what is going on.

The wierd thing now is that since I cant get it over 10 bar, there should be almost no water, but there is still some. I observerd that tuning the OPV into the "sweet spot" actually made it leak less water from the OPV during brewing - and this is where I have it now.

Even tho things are odd, the coffe turns out good. It flows much more stable without spikes and the cone holds for longer before collapsing.
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