# Group seal leak/blowout



## spoxehub (Oct 24, 2014)

Well this is a bit odd....

Just started happening this has. When I rebuilt the Personal 1, I replaced the original and very knackered NS group seal (OEM on this machine was 7mm, at least that's what came off it anyway) with a new, admittedly thicker at 8.3mm blue silicone one about 6 months ago. I didn't bother putting the paper shim behind the new seal due to the extra thickness taking up the slack, worked fine, PF locks in spot on etc etc.

Now as of last week it fairly regularly blows out of the group head at random, crapping water everywhere. I've pulled the seal, looks fine. Clean, still flexible, no damage. Reseating it solved the problem for 10 or so shots then BAM it's out again.

The only other thing that has changed recently is I replaced the pump, but the pressures etc are all as previous. No change there.

Your comments, thoughts and wisdom, as ever, welcome. Also sarcasm.


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## joey24dirt (Jan 28, 2017)

spoxehub said:


> Well this is a bit odd....
> 
> Just started happening this has. When I rebuilt the Personal 1, I replaced the original and very knackered NS group seal (OEM on this machine was 7mm, at least that's what came off it anyway) with a new, admittedly thicker at 8.3mm blue silicone one about 6 months ago. I didn't bother putting the paper shim behind the new seal due to the extra thickness taking up the slack, worked fine, PF locks in spot on etc etc.
> 
> ...


Dodgy portafilter?


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## spoxehub (Oct 24, 2014)

joey24dirt said:


> Dodgy portafilter?


HAHAHAHAHAAAAA

Nah mate, this happens with the PF you made AND the OEM NS one.


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## DavecUK (Aug 6, 2013)

I assume the pf is unwinding from the group, not that the seal is coming out?

You using an aftermarket silicone seal?


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## espressotechno (Apr 11, 2011)

Group seal inserted the wrong way up ?


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## spoxehub (Oct 24, 2014)

DavecUK said:


> I assume the pf is unwinding from the group, not that the seal is coming out?
> 
> You using an aftermarket silicone seal?


No mate, with the PF locked in, the seal is blowing out of the group head. It's pretty impressive.


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## spoxehub (Oct 24, 2014)

espressotechno said:


> Group seal inserted the wrong way up ?


Could be....it's got ridges one side and a smooth other side. I installed ridges up. So smooth meeting the PF.


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## espressotechno (Apr 11, 2011)

That's the correct seal install.

Is the silicone seal a loose fit, or a tight fit ? ( It should be a tight push-fit)


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## spoxehub (Oct 24, 2014)

espressotechno said:


> That's the correct seal install.
> 
> Is the silicone seal a loose fit, or a tight fit ? ( It should be a tight push-fit)


Tight push fit it is.


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## Rob1 (Apr 9, 2015)

Blocked shower screen?


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## spoxehub (Oct 24, 2014)

Rob1 said:


> Blocked shower screen?


No.


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## spoxehub (Oct 24, 2014)

By way of update, I've just gone ahead and replaced the seal. So far, so good.


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## Paul Pratt (May 15, 2013)

NS seals are pretty confusing, even for their distributors. They have flat and conical in 2 different thicknesses. Either shape works but from my dealings it seems that it is up to preference of the local distributor or the end user or whether they favour flat or conicals.

On the conicals the flat side faces up, the angled side faces down. A little lubricant on a seal does help the initial insertion. A sheen of lubricant is all you need, not big globs of the stuff. On the seals I make the 8.3mm are red and the 9mm are blue.


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## spoxehub (Oct 24, 2014)

Paul Pratt said:


> NS seals are pretty confusing, even for their distributors. They have flat and conical in 2 different thicknesses. Either shape works but from my dealings it seems that it is up to preference of the local distributor or the end user or whether they favour flat or conicals.
> 
> On the conicals the flat side faces up, the angled side faces down. A little lubricant on a seal does help the initial insertion. A sheen of lubricant is all you need, not big globs of the stuff. On the seals I make the 8.3mm are red and the 9mm are blue.


Thanks Paul. Yes, agreed that OEM NS seals aren't straightforward. I replaced the original with an 8.3mm Cafelat blue silicone seal, which has now been replaced with an 8.0mm Cafelat red silicone seal.

You make seals, you say?


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## chimpsinties (Jun 13, 2011)

I've had this exact same problem with my Gaggia Classic recently. Basically nothing changed but it seemed to start happening and new seals (either silicon or OEM) didn't solve it.


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