The hard version: 85 ShA instead of the usual 70
Most O-rings in an espresso machine have a hardness of 70 Shore A. This one, at 85 ShA, is considerably firmer – and that is no accident but a specification. Under pressure, a harder ring is squeezed less into its gap. That is exactly what is needed at points where high pressure is present or the groove is comparatively wide.
In practice this means: a softer ring with the same dimensions could be fitted and would even seal for a short time. Under operating pressure it then starts to creep or gets extruded. That is why number H.1.004 belongs here, and nothing that merely looks like it.
When it is due
A sealing point drips or sweats under pressure but not at rest – a typical sign of an extruded or overly soft ring. The removed ring is hard, cracked or noticeably flat on one side. Material stays behind in the groove when you remove it. Or a threaded connection has been undone anyway and is now being properly resealed.
At a glance
| Type |
EPDM O-ring, hard version |
| Location |
Sealing point inside the machine; our documentation does not state the exact position |
| Fits |
Order by part number; our documentation does not name a single model |
| Scope of delivery |
1 O-ring |
| Part number |
H.1.004 |
| Version |
Inner diameter 10.77 mm, cross-section 2.62 mm, EPDM, hardness 85 ShA |
| Installation |
Fitting by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
Because the ring works at a pressurised point inside the machine, the machine is depressurised beforehand and checked for leaks afterwards. We do not provide step-by-step instructions: the position is only listed in general terms, and a harder ring is more difficult to pull over edges – anyone using a screwdriver for this will damage the groove or the ring. This is a job for a qualified technician with the right tools.
Who it is for
For service companies that take hardness specifications seriously, and for anyone who has H.1.004 in their documentation. Anyone who has ever had to do a sealing point twice because the ring leaked again when pressure built up the second time knows why the 85 ShA is in the table here.
What goes with it
Not to be confused with the EPDM O-ring 1.78 × 10.82 mm: almost the same inner diameter, but a considerably thinner cross-section and softer material – two different positions. For very high temperatures we also stock the PTFE seal 10 × 2.5 mm. The full range of seals is in the Original spare parts section, and the rest of the brand's range in the La Marzocco accessories and spare parts section.
From our workshop in Bern and Zurich: We never fit hard O-rings using metal, but with a rounded plastic stick – at 85 ShA a scratch in the ring immediately means a leak, because the material does not deform to close over it. And after fitting we test not only cold but once more under operating pressure: most of these sealing points only give themselves away then. Our own routine, not a manufacturer's specification. While waiting for the pressure to build, we usually drink the Very Nutty, because it has character even in a workshop cup; the Nutty Delight is milder. Everything else under Coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold after installation or a trial fitting on the machine. So before ordering, please check the model, year of manufacture and serial number of your machine – or drop us a quick line and we will clarify the fit together. Your statutory rights regarding defective goods remain unaffected.
Frequently asked questions
Why 85 ShA and not 70?
Because the manufacturer specifies a harder ring for this position. Harder rings withstand pressure better and are less easily pushed out of the groove.
Can I use a softer ring of the same size?
We do not recommend it. It often seals at first and then fails again under operating pressure. Use number H.1.004.
Which figure is the inner diameter?
10.77 mm is the inner diameter, 2.62 mm the cross-section. For this position, the diameter comes first.
Where does the ring sit?
Our documentation lists it without an installation location. We will not invent one. Send us the serial number of your machine and tell us where you found the number, and we will identify it.
Can I see the part at your shop?
Yes. Come to our showroom in Bern at Gerberngasse 44 or in Zurich at Hagenholzstrasse 50b. Bring the old ring with you and we will measure it together.
Unsure about the hardness? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
