# Gaggia "popping" group seal when steaming



## crmdgnly (Apr 12, 2017)

Hello

I have a Gaggia symptom I'd like advice on please.

I don't do milk that often, so hadn't really noticed this, but the last few times I have steamed milk, there has been a fair bit of steam from the grouphead, culminating in a "pop" and the group seal being dislodged by a few mm, enough to not allow the portafilter to be attached without re-seating the seal.

Since I mostly make espresso, this doesn't crop up that often.

Any ideas why, and whether I should be concerned?

Thanks


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## jimbojohn55 (Jan 15, 2016)

sounds as though something is not right, do you descale? how old is the machine? how old is the group head seal?


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## DaveP (Jul 14, 2017)

> Any ideas why


The boiler may be bunged up with scale, so descale. also the steam stat maybe operating at far to high a temperature, but less than what the thermal fuse melts at.

So descale first and see if that helps, then change the steam stat if required.


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## timmyjj21 (May 10, 2015)

To pop the group seal, you need excess pressure behind it, which basically shouldn't happen. Take off the shower screen and the aluminium dispersion plate and ensure it is all clean, remove all buildup of coffee oils. If the dispersion plate is corroded badly and potentially allowing leakage around behind the group seal then I would be replacing it.

Make sure the group seal is the correct way around. All writing and rounded edges go in, with the flat edge and sharp corner outside.

If all clean and looking good, then check the steam thermostat, but it's unlikely to be the cause simply because there shouldn't be an volume of water or steam behind the group seal to begin with!


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## crmdgnly (Apr 12, 2017)

I will look at all of those things.

The machine is a Paros from around 2000. The boiler was new a couple of months ago. I haven't descaled since the boiler replacement as I have been using bottled water, but that's now on the list. Group seal replaced at the same time, with rounded edges up (contacting the group head). Dispersion plate new brass one, and very clean. Will double check it seated correctly.

When (if?) I do some steamed milk again I'll try and take a video.

Thanks for taking the time to help


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## El carajillo (Mar 16, 2013)

Check that the dispersion disc is seated squarely and the seal, it sounds odd that the steam is getting behind the seal. Also check the seal is not a loose fit (dicky seal)


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## timmyjj21 (May 10, 2015)

Ah! I had issues with a particular brass dispersion plate blowing my group seal when removing the portafilter after steaming. If you look carefully, the aluminium dispersion plate is NOT a cylinder, It is actually tapered. This extra diameter at the top holds the group seal in place. One particular type of brass dispersion plate didnt take this into account. You may be able to subtly reposition it to work better, but I actually ended up picking a completely new plate and design from a different seller. This appears to be a rare issue and may be just machining tolerance.


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## crmdgnly (Apr 12, 2017)

I have this one from the Espresso Shop...

https://www.theespressoshop.co.uk/en/gb/Gaggia-Brass-Shower-Plate-Holder-57x14mm---WGA16G1002/m-1976.aspx

I always take the portafilter out before turning steam on; maybe I shouldn't?



timmyjj21 said:


> Ah! I had issues with a particular brass dispersion plate blowing my group seal when removing the portafilter after steaming. If you look carefully, the aluminium dispersion plate is NOT a cylinder, It is actually tapered. This extra diameter at the top holds the group seal in place. One particular type of brass dispersion plate didnt take this into account. You may be able to subtly reposition it to work better, but I actually ended up picking a completely new plate and design from a different seller. This appears to be a rare issue and may be just machining tolerance.


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## El carajillo (Mar 16, 2013)

It should not make any difference. The dispersion disc in the add looks fine. Try removing it and trying it in the seal in hand, should be a close / good fit.


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## crmdgnly (Apr 12, 2017)

I removed the pate, all appeared fine and it was a comparable size (visually) to the old aluminium one I removed.

No milk based beverages as yet, but I will try it soon, and if it recurs, video it and also try the old aluminium dispersion plate and see if it still happens.


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