The steel washer that keeps the GS3 conical valve at the right height
A shim looks like nothing, yet it decides whether an assembly sits without play. On the conical valve of the GS3 MP it lies between two surfaces that work against each other and gives the screw connection a defined bearing surface. If it gets bent during disassembly, forgotten or replaced by a similar-looking washer made of a different material, the height is no longer right.
This washer measures 14,2 × 30 × 2 mm, is made of steel and carries the part number I.1.091. It is the hard counterpart to the Teflon washer I.6.005 of the same size – same location, different material, different job.
When it needs replacing
The old washer is bent, worn in or shows a clear pressure mark. It has started to rust. It disappeared during disassembly – that happens more often than you might think. Or the assembly has play after reassembly even though everything is tight: then height is missing, and the washer is the first place to look.
At a glance
| Type |
Washer, steel |
| Location |
on the conical valve of the GS3 MP brew group |
| Fits |
La Marzocco GS3 MP with conical valve. Send us the serial number and we will check the fit. |
| Included |
one washer |
| Part number |
I.1.091 |
| Version |
14,2 × 30 × 2 mm, steel |
| Installation |
Installation by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
The washer sits inside the machine on a pressurised assembly. Only work on the machine when it is switched off, cooled down and depressurised. Place the old washer next to the new one before you fit it, and compare inner diameter, outer diameter and thickness. We deliberately do not provide step-by-step instructions here.
Washers and shims in the catalogue
With a shim, what matters is the material, inner diameter, outer diameter and thickness – the name alone is never enough. These are the items we stock:
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Ø 30 mm outer: I.1.091, 14,2 × 30 × 2 mm, steel (this item), I.6.005, 14,1 × 30 × 2 mm, Teflon, I.1.033, 10,7 × 30 × 1,8 mm, A2 stainless steel and F.1.032, 10 × 30 × 2 mm, PTFE
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Smaller sizes: L100/D, 10 × 14 × 1,5 mm, copper, L165/2, 16,5 × 26 × 1 mm, brass and I.1.170, 14 × 7 × 0,5 mm, brass
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Copper washers for the pump: L180/1, 22 × 17 × 1,5 mm, L100/1A and L4002
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Without stated dimensions: I.6.024, without scratch protection
Two washers with almost the same dimensions are not interchangeable if the material is different: a copper washer is allowed to settle, a Teflon washer is springy, a steel washer stays hard. When in doubt, the number on your old part decides.
Who it is for
For workshops that strip down a GS3 MP and replace the small parts at the same time, and for anyone searching for exactly this washer with the number I.1.091 from a service document.
What goes with it
On the same conical valve you will find the Teflon washer I.6.005, the M5 nut, the 5 × 23 pin and the M5 × 5 socket screw. Everything else for the machine is under La Marzocco GS3 spare parts and in the category Original spare parts.
From our workshop
In Bern and Zurich, when we strip a machine down, we lay the small parts out on a cloth in the order they come out – washer, nut, pin, side by side rather than in a bowl. Anyone with three almost identical washers in a bowl sorts them afterwards by feel, and sooner or later that goes wrong. This is our routine, not a manufacturer requirement. Until the group is closed again, there is usually a cup next to it: Nutty Delight, Cozy Chocolate or Very Nutty. More under coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are procured specifically for each order and cannot be resold after being installed or test-fitted on a 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.
Frequently asked questions
How does this washer differ from the Teflon washer I.6.005?
In the material and by a tenth of a millimetre in the inner diameter: I.1.091 is made of steel and measures 14,2 × 30 × 2 mm, I.6.005 is made of Teflon and measures 14,1 × 30 × 2 mm. They are two different items, and they cannot be swapped for each other.
Can I use a standard washer from a DIY store instead?
We advise against it. The dimensions do not correspond to a common standard, and even half a tenth of a millimetre more thickness changes the height of the assembly.
Do I need one washer or several?
One washer is sold. How many are fitted in your machine depends on its design – count them as you take it apart.
Is a seal included?
No. Only the washer is supplied. O-rings and seals are separate items.
Can I see the part in your shop?
Our showrooms in Bern (Gerberngasse 44) and Zurich (Hagenholzstrasse 50b) show a wide selection, but not our entire range – the display changes. Drop us a quick line at [email protected] before your visit, and we will check whether the product you have in mind is currently there.
Questions about the fit? Write to us at [email protected]. Delivery across Switzerland and to Liechtenstein in 2-4 working days.
