Variable Pressure Output from Group Head

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Doc-Ernie

Variable Pressure Output from Group Head

Post by Doc-Ernie » Tue Apr 15, 2008 1:36 pm

I have not been able to find report of the problem I have experienced, so thought I would see if others on this forum know how I should proceed.

We have a Vivaldi I which is about 2.5 years old. When first set up it ran beautifully for about 8-9 months (using a nice water filtration system since day 1, and performing monthly machine maintenance = backflushing, screen cleaning, and generally being kind), then without warning one day we noticed the force of water coming from the group head was not as vigorous, nor the pump noise as loud as we had grown accustomed to, and in order to get decent crema had to coarsen the grind from our Mini-Mazzer. Convinced there was an internal pressure pump problem, I returned the machine to our local distribution/repair center in Seattle - who could find nothing wrong (???).

So we put up with okay crema for over one year (nothing like we had those first 8-9 months though). Recently we had a whole house water pressure regulator put in, as our water pressure was found to be over 90psi. This immediately affected our Vivaldi I, so that the crema was now almost non-existent. I decided it was time to order the portafilter pressure gauge from Chris' Coffee service to see just where everything was running.
Pressure at the group head was only 3.5bar (with a recommended 8.2-9.0). Amazingly I had to turn nut "B" almost fully in clockwise, and suddenly we had pressure! I was then able to adjust the expansion valve pressure opening correctly, and then adjust the group head pump pressure to nice 8.8bar. The results were phenomenal - we had a machine running/sounding like it did on day 1, wonderful thick crema filling the whole shot glass, etc....BUT these changes only lasted 24 hours sadly, and suddenly we had again a loss of pressure and sound when hitting the 1 or 2 cup shot switch - again with lousy crema.

A re-check of the pressure revealed we were again back to 3.5bar. This time I was determined to flush the machine of any possible impurities, so did remove the entire expansion valve assembly and replaced the rubber expansion valve washer. Flushing lots of water though both the group head and the open expansion valve. So again back to adjust pressure, and once again getting no change in pressure until the adjusting nut "B" was almost fully turned in, then suddenly again the pump sprang to life and group pressure was over 14bar. A bit of tinkering with the adjustments, and once again we have a machine running like new! Group head pressure is around 8.8bar, expansion valve set perfectly, excellent crema, vigorous sound when dispensing shots, etc....

SO, my question is - might someone else have experienced these problems? and though I would love our machine to run this way forever, am skeptical, thinking this is likely temporary. Is there a part that needs to be replaced (pump)??
It's like our machine has its "A game", and a "D game", and you never know which one will show up until you hit the shot dispenser button; yet it is clear once it falls to its "D game", it will stay there and not ever go back to the "A game" unless I readjust all parameters again.

Any suggestions (beyond going for a Vivaldi II) would be most helpful and deeply appreciated!
Thank you!
Ernie

Niko

Post by Niko » Tue Apr 15, 2008 4:40 pm

Ernie,
I've never heard of this problem :?

This is a dumb question, but did you tighten the locking nut to hold the adjustment you made for the group pressure? Just thought I'd ask since that seems to be moving possibly by the vibrations in the machine. :dontknow:

Doc-Ernie

Post by Doc-Ernie » Tue Apr 15, 2008 5:14 pm

Niko,
Thanks for the input, yet sounds like we are both puzzled still. Yes, I did tighten the lockring "A" on both adjustments, so no vibration influences.

My wife and I enjoyed our afternoon double, especially since Vivaldi was still on its "A-game". Just for the record, using currently Zoka espresso beans in the Mini-Mazzer, and have been tamping for quite some time with the ESPRO tamper (which I love as it eliminates the tamping pressure variable between my wife and I) - so we can keep a uniform grind and between 25-32 second shots.

I have thought either the pump has a problem, or there might still be some debris internally that interferes with water flow to the group head intermittently. Yet neither of those theories seem to hold up to further critical thought (though admittedly this is why I thought I would post my experiences in hopes someone else could provide the answer).

Hopefully more discussion to come!
Ernie

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chas
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Post by chas » Tue Apr 15, 2008 10:22 pm

It sounds like it might be the pump. I was looking at the replacement pumps on the Chris Coffee website and noticed that the adjuster screw doesn't seem to be included with the new pump - or at least it's not shown in the photo.

If I were you the first thing I'd try is to remove that adjuster mechanism from the pump and see if there is any debris in that area or anything that appears worn with that mechanism. Perhaps the adjuster is separately purchasable.
Chas
LM GS/3 & LaSpaziale Dream v 1.23 (US 120V)
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Doc-Ernie

Post by Doc-Ernie » Wed Apr 16, 2008 11:25 am

Chas,
Thanks. Looks like I will now have a chance to flush out the pump, as this morning our Vivaldi I was back to its "D-game".
Thinking I'll turn it off, shut off the water supply, remove completely parts "A" and "B", clean them off after inspection and then turn on the water supply and flush the pump as best I can with the adjuster out (shower time!). Then re-install everything, re-adjust and report back.....

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JohnB
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Post by JohnB » Wed Apr 16, 2008 1:09 pm

Its possible that having your water pressure that high(90psi) could have damaged the pump?? Its surprising that with pressure that high you didn't see much higher pressure at the group head as the pumps are normally adjusted at 30 psi.

Do you have a filter on the line feeding the machine?
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Doc-Ernie

Post by Doc-Ernie » Wed Apr 16, 2008 6:26 pm

Well everyone, thank you for the diagnostic tips!

I did pull off the A & B adjusters from the pump, and the parts internally that are accessible are easy to clean and replace. I did not find any major gunk to speak of, flushed the pump by opening up the water flow through the filter dedicated to the machine, put it all back together and adjusted the pressure which again was at 3.5 bar. And once again, the needle did not budge until adjuster A was turned all the way in.

At this point I called Chris Coffee repair, and got great advice (as per usual from them). He thought as well my pump was bad, but wanted me to check the motor first by removing the clamp holding the motor to the pump (which proved difficult as I could only rotate the screw 1/4 turn at a time), inspect the coupling (very corroded in my case with debris in the area and some rust/oxidation to the spline end) and the turning of the splines (the motor spline spun freely and very smoothly, the pump spline frozen). With the machine back on the motor immediately kicked on and spun as it should (detached from the pump).

So ordering at the moment a replacement compact pump for Vivaldi from Chris Coffee, and will post a reply once all is put back together. Wondering now if indeed the pump was damaged by high water pressure, which may have leaked thru internally to corrode the bearings of the pump spline. Also hoping the motor will be okay - thinking it has been strained for quite some time. Anyway, will find out and report back....

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chas
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Post by chas » Wed Apr 16, 2008 7:24 pm

Great to hear your machine will soon be back at 100%. Fortunately, the pumps are not too expensive in the scheme of things. The only unfortunate thing is that it sounds like the pump actually went bad when the S1 was still under warranty.
Chas
LM GS/3 & LaSpaziale Dream v 1.23 (US 120V)
Mazzer Kony E, Customized Rocky
Hottop P/B

Doc-Ernie

Post by Doc-Ernie » Tue Apr 22, 2008 1:13 pm

Okay, here is the final (I hope) update on our Vivaldi I. The bad pump I pulled off our machine was actually not frozen as I had stated, but the spline run by the motor was very stiff and hard to move. This seems to make sense then why at least the Vivaldi would work for a time with adjustments, then perhaps came to rest on a bad bearing or two and no longer functioned. I tried to pull the old pump apart just to investigate further, but it is press fit together and I could not manage it.

With our new pump in place (which also had a surprisingly firm, but smooth rotating shaft) our machine is consistently delivering its "A-game"; vigorous pump action/water dispersion and fantastic shots. We're hoping it stays this way for good! (Note - I was able to actually test "spin" or turn two new pump shafts, and they were both very smooth in action, yet took more muscle to rotate than I initially anticipated. Mentioned so that those in the future replacing a pump will not be dismayed by the firm action.)

Replacing the pump is not too difficult. The greatest difficulty is in unscrewing the clamp which binds the pump shaft to the motor. This task was made far easier by purchasing a ratcheting screwdriver, which came with multiple sized drivers - a fantastic little tool for working in tight spaces. Other than than the clamp it is only a matter of removing and replacing the water intake and output hoses and their fittings, then readjusting the pump pressure to 8.2-9.0 bar, and you will be good to go!

Thank you all for your help and kind advice.

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Post by zoey » Tue Apr 22, 2008 4:38 pm

Glad you got your issue resolved. :wink:
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