Posted Mon Sep 3, 2012, 8:02am Subject: Giotto releases water when pulling shots or backflushing
Grateful for advice:
I have a circa 2008 Rocket Giotto which I use to make two or three most excellent espressos a day. A week or so ago it started leaking water from the grouphead column (the vertical chrome cylinder behind the Starship Enterprise, if you will...).
It doesn't leak when simply at the ready; it doesn't leak when I lift the lever and let water flow through the grouphead. It only leaks when there's backpressure: i.e., when I'm pulling a shot (it starts leaking when the preinfusion is done and the pressure starts ramping up) or backflushing (water flows down from the column as I build up the pressure, before I 'release' it).
I've done backflushing with Cafiza and have run Dezcal through the grouphead. I've taken off the column's top nut (when the machine was off) and made sure nothing there is blocked or clogged. But that's all I know to try.
Again: grateful for any advice. I could buy a new grouphead and install it, but would love to hear diagnostic and/or repair suggestions short of that.
Posted Mon Sep 3, 2012, 8:49am Subject: Re: Giotto releases water when pulling shots or backflushing
Download the Vibiemme Domobar Double owners manual either at 1st-line or at espressocare.com. The manual features a full, illustrated explanation of how the E-61 group works. It shows all modes in cut-away views and will help you understand what is happening. Then go to my website and use THIS illustrated, step-by-step article on how to overhaul an E-61 group. You likely need new seals and if you can use basic hand tools it is not a difficult job.
Posted Mon Sep 3, 2012, 11:41am Subject: Re: Giotto releases water when pulling shots or backflushing
Randy: this is very helpful.
RichardCoffee: if by this you mean the gasket that snugs to portafilter to the group head, I replaced it about nine months ago. But I can't intuitively understand how that gasket, which seems to fit well, would affect the outpouring of water from the bottom of the exhaust column. Should I replace the group head gasket regardless?
Posted Mon Sep 3, 2012, 11:59am Subject: Re: Giotto releases water when pulling shots or backflushing
I think he became a bit misled by the terms you used in your original description.
The water from the "exhaust" port at the bottom of the group is most likely from a leaking exhaust valve gasket. The exhaust valve is held by the strongest spring in the group and so that seal takes the greatest amount of force against its seat and that will cause it to degrade quicker than the other two seals. if you have a mind to, and if the valve comes apart without damage as described in my repair article, you can pry out the seal carefully and flip it over. it will work for a day or two that way, but it is one way to test it before ordering parts. Also, taking apart all three valves will assure you that the metal parts are sound and that is good to know before placing an order. Applying heat and using a penetrating oil is a good idea as well since some of the valves are assembled with thread locker, or may be a bit corroded in the tiny threads.
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