A fluoroelastomer ring for hot, permanently tight connections
An O-ring is the most inconspicuous component of an espresso machine and, at the same time, the one that is most often the reason for a service visit. This one measures 20.22 millimetres inner diameter with a 3.53 millimetre cross-section and is made of FKM, the material usually sold under the name Viton. The part number is L105/A.
FKM is the choice when things get hot for long periods and when grease, oil or more aggressive cleaning agents are involved. The ring stays elastic for longer than a standard compound, but it is not any cheaper for it. Anyone who swaps it for a softer EPDM ring of the same size will not notice straight away – only when the spot starts weeping again after a few months.
When it's due
A tired O-ring announces itself quietly. First, a small drop of water appears at a threaded fitting and keeps coming back, even though you wipe it away. Then a white limescale ring shows up in a place where there was none before. When removed, the ring is hard, flattened at the contact surfaces and can barely be rolled over your finger instead of springing back. At that point at the latest, it needs replacing, not retightening – because retightening only squeezes it further.
At a glance
| Type |
O-ring, round, without back-up ring |
| Dimensions |
Inner diameter 20.22 mm, cross-section 3.53 mm |
| Material |
FKM (fluoroelastomer), hardness 70 ShA |
| Installation position |
Not specified in our documentation – please check using the part number |
| Fits |
La Marzocco machines that list the number L105/A at this position |
| Scope of delivery |
1 O-ring |
| Part number |
L105/A |
| Version |
Original spare part |
| Brand |
La Marzocco |
| Installation |
Installation by a specialist recommended |
Important for installation
This ring sits in a connection that carries water or steam. Only work on the machine when it is depressurised, cooled down and disconnected from the mains, and release the boiler pressure completely before you open a threaded fitting. We deliberately do not give step-by-step instructions here – if you are not sure of the installation position, a service appointment will serve you better than trial and error. After reassembly, the spot should be checked once more while warm.
Who it is for
For technicians who service a La Marzocco and have the number L105/A in front of them on the exploded view or the service sheet. Also for businesses that keep a small stock of wear rings so that a dripping fitting does not turn into unplanned machine downtime. For home users without a service background, an O-ring with an unknown installation position is rarely the right spare part – in that case, it is better to drop us a quick line.
What goes with it
The second FKM ring in our range is the O-ring 2.62 × 17.13 mm FKM 70 ShA; don't mix the two up, the cross-section is considerably thinner. For the lever machine there is the O-rings for LEVA in six sizes assortment. You will find all other wear parts in the Original spare parts category and in La Marzocco accessories and spare parts.
From our workshop in Bern and Zurich
As a rule, we replace O-rings as a set rather than individually. If a threaded fitting is open anyway, the second ring costs a few francs – a second service appointment costs half a morning. That is our routine, not a manufacturer requirement. And once the machine is running again, for us the first test shot belongs on a bean that honestly reveals faults: Nutty Delight is our house standard for this, Cozy Chocolate the sweeter option and Very Nutty the stronger one. Everything else is 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 test fit on the machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a line and we will clarify the fit together. Your rights in the case of defective goods remain unaffected.
How do I know whether I need this ring?
By the part number. If your service sheet or the exploded view says L105/A, this is the ring. An O-ring can hardly be identified by eye, because a few tenths of a millimetre decide whether it fits.
Can I use an EPDM ring of the same size instead?
We advise against it. FKM and EPDM behave differently with temperature, steam and cleaning agents. Where the manufacturer specifies FKM, FKM is what belongs there.
Which machine is it for?
Our documentation does not name a model for L105/A. Send us your machine's serial number and we will check the fit before you order.
How many rings do I get?
One. If you need several for a service, simply enter the quantity in the cart.
Can I pick up the part from you in the showroom?
Yes. We are in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Let us know shortly beforehand and the part will be ready for you.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
