Hi Eric, thanks for your advice, I'll keep a close eye on that valve.

I assume it removes air from the water? If so and it was faulty I suspect that could explain the air pocket (lock?) I had the other day that caused the boiler to not come on and the alarm to sound.

Seems odd that if it was cracked it would work fine most of the time, remember that I've probably turned the machine on 180+ times since it first leaked and it's only leaked about 5 or 6 times. Then again I have no idea how the valve works.

By the way - the last time you gave me some advice based on your recollection of VBM Domobars it resulted in my single biggest improvement in the cup so far! The second biggest improvement was installing your digital thermometer, you certainly are an endless source of knowledge and it's great that you share it with us so freely.

Cheers, once again!

Then again I have no idea how the valve works.

This might help: search.php?keywords=deaeration+valve&te ... t=0&ch=300

I AGREE that this small percentage of leak occurrences is odd. But the source of the leak is highly unlikely to be anything "topside" because of the volumes you have reported.

The typical alarm in a Gicar/Giemme control box occurs when the pump runs for an extended time without stopping. The control box will automatically stop the pump and sound an alarm. The alarm may also be set to activate when the reservoir water level falls low but on the Vibiemme, this also shuts down the machine as a whole. Unfortunately, each machine brand is different and most have no audible alarm at all. And, to make matters even more confusing, NZ machines may be configured differently (from an alarm standpoint) than US or European Vibiemme machines.

The second picture in your original post is that of the boiler fill solenoid valve. There should be NO LEAKAGE there. I would remove the coil and clean the top of the housing with a paper towel dampened with a little white vinegar. Make sure that nut is tight.

erics wrote:I AGREE that this small percentage of leak occurrences is odd. But the source of the leak is highly unlikely to be anything "topside" because of the volumes you have reported.

I agree that the volumes of water you have reported from the leak are large, and have occurred often enough that if they were coming from any fitting in the upper regions of the machine would leave easily-seen signs such as mineral deposits of the beginnings of corrosion on metal parts (brass and copper).

Thanks to everyone that has had some input, it has certainly helped me learn a thing or 2 about my machine.

After it leaking 2 mornings in a row I put this thread up and started watching it like a hawk, since then not a single drip.

I'll keep watching and update the thread when I find something.

Thanks again.

So it happened again this morning while I was standing in front of the machine (unfortunately the cover was screwed on).

Machine on, pump activated for 5-10 seconds.
About 3 minutes later the pump comes back on and stays running, the boiler gauge is reading 2bar!
After 30 seconds the pump is still running and I switch the machine off, warm water is pouring out the bottom.

I open the machine up and find water sprayed all over the place, however the boiler and above the boiler look to be bone dry.

[EDIT]
7 hours later I switched the machine back on, case off this time and watched. The pump did not come on, after 2 minutes water was streaming out of the valve on top of the boiler (SOLENOID VALVE REDUCTION anti-vac valve). It was pooling on top of the boiler and then running down the side.

I switched it off, then back on 5 minutes later, this time water started to jet out of the valve, not fast enough to hit the top of the machine but close.

I assume that this morning it was shooting out of this valve and clearing the boiler, hitting to underside of the top grate and then falling down beside the boiler and covering eveything (as you can see in the photos below)
[END EDIT]

You can see water has sprayed up and hit the top grate.


On the other side (the boiler side) there is no sign of this at all.


It appears to me as if the water sprayed up from the inlet water solenoid valve (assuming that is possible - could warm water be coming from here?) or somewhere in this area.



Here's a shot of the boiler from the same side as the photo above

I just edited the earlier post, I have just now watched a lot of warm water exiting the valve on top of the boiler. The 2nd time I powered the machine on it was shooting out, suggesting that this morning it must have shot out of this valve and cleared the boiler completely!

I now need to find out all about this valve I suppose. And consider removing it.

Does anyone think the valve itself could faulty or is this a symptom of another fault, e.g. the boiler probe or brain unit?

That is the boiler safety valve spewing the hot water. It is doing this because the boiler overfilled and then some.

You will need to syphon some water from the boiler or use the hot water tap to remove water from the boiler until the autofill system establishes proper level. But this is a secondary problem.

Under normal conditions, only two items can initiate pump operation. One is, of course, the brew lever and the other is the autofill system. There should be a small amount of clearance (maybe 1 mm) between the brew lever and the contact "button" on the face of the machine. Is this so?

Have you checked the wiring from the water level probe to the control box as Kitt earlier suggested? Have you removed the probe? At this point I would be tempted to simply replace that wire in its entirety. Any disconnection or poor contact at the terminations will cause the pump to come on and try to fill (overfill) the boiler.

I haven't taken any action yet, however I did just buy an 18 piece spanner set in preparation.

I'm sure there is clearance between the brew lever and the button. Will double check when I get home tonight.
I'll also check the probe wire.

I just found this on an NZ parts site...

http://www.espresso.co.nz/espresso-mach ... ler-style/
"Anti-vacuum valves prevent the buildup of a vacuum withing espresso machine boilers as they cool. As the boiler cools steam condense back to water and the steam/water volume reduces creating a vacuum, the anti-vacuum valve opens to allow the intake of air to prevent a vacuum being created. When a cold espresso machine begins to heat and steam is produced, the pressure closes the anti-vacuum valve, creating a sealed boiler. A worn anti-vacuum vale will allow steam to escape the boiler and should be replaced immediately."

Makes it sound like valve is there to let air in rather than pressure/steam/water out?
Also suggests a worn valve would let steam escape the boiler and it should be replaced. Do you think this is worth investigating?

Based on what you've said Eric, I'm thinking the current theory is...

A faulty wire/contact (or probe) caused the boiler to overfill this morning, and water jetted out of the anti-vac valve as a result.
Later in the day, the boiler is now overfull and when I switched the machine on the pump did not come on but the element did, as pressure built in the boiler water started to escape out the anti-vac valve.

Does that sound about right?

Is there anything I need to do before removing valves, probes from the boiler. Other than un-plugging the machine, and perhaps emptying some water through the hot water tap.

Most of the seals appear to have a white lock-tight (?), am I ok simply reattaching and tightening after inspection? Or do I need to get some of this white lock-tight stuff first?

The valves are simply doing their job (to stop the boiler exploding from overpressure) Concentrate on checking the wiring and level probe.

White stuff is most likely teflon tape by the look of it. They really went to town with it.Can't hurt to re-apply it when re-fitting threaded items

Thanks Kitt, looks like I'm going to spend the night taking things apart.

Reading about that valve... sounds like it sits there open, when the boiler has heated a little the pressure closes the valve and the boiler is sealed. As the boiler cools down and pressure drops the valve re-opens and allows air in, stopping a vacuum being created.

Does leave me wondering how this same tiny valve opens when the pressure gets too high? Anyway I'll check the probe and wires tonight, might have to stop off at the hardware store again and pick up some teflon tape.

Thanks for all the help so far, I really do appreciate it.