The seat the gasket presses against – for the KB90 steam tap
A steam tap seals at one single point: where the gasket meets the seat. Every time you open and close it, this surface takes the load, and in steam operation heat and limescale add to it. At some point the seat is no longer flat – and then even the best new gasket only lasts a few weeks.
This seat belongs to the steam tap of the KB90 and carries the part number A.5.119.R. It is the counterpart that usually gets forgotten during a service, even though it accounts for half of the sealing effect.
When it's due
The steam tap keeps dripping or hissing quietly even though the gasket is new. You have to turn it tighter and tighter to stop it. The removed gasket shows an irregular, one-sided imprint. Scoring, limescale crusts or a circumferential groove are visible on the seat. Or the tap only closes tightly in one particular position.
At a glance
| Type |
Valve seat |
| Location |
in the steam tap of the KB90 |
| Fits |
La Marzocco KB90. Send us the serial number and we'll check the fit. |
| Scope of delivery |
one valve seat. Gasket and shaft are not included. |
| Part number |
A.5.119.R |
| Specification |
We have no documentation on material, thread or dimensions. |
| Installation |
Installation by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
The seat belongs in a steam-carrying fitting. Only work on the machine when it is switched off, cooled down and depressurised. Whoever replaces the seat also replaces the gasket in the same go – a used gasket on a new seat is only half the repair. We deliberately don't provide step-by-step instructions here.
Who it's for
For workshops and businesses with a KB90 who want to repair a dripping steam tap properly instead of changing the gasket every few months.
What goes with it
The KB90 steam tap also includes the shaft A.5.120, the brass body with knob, the knob and the service kit for the steam valve. Everything else for the machine can be found under La Marzocco KB90 spare parts and in the Original spare parts section.
From our workshop
In Bern and Zurich, we hold the removed seat up to the light and turn it slowly: a worn-in groove shows up as a thin dark ring that you can barely see when the seat is lying on the table. That's our routine, not a manufacturer's specification. Until the tap is back together, there's 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 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 send us a quick message and we'll clarify the fit together. Your rights in the event of defective goods remain unaffected.
Frequently asked questions
Is the gasket included?
No. What you get is the valve seat. Gaskets are separate items – the KB90 steam valve service kit is the right place to start.
Why does my steam tap keep dripping after changing the gasket?
Because the gasket is only one half of the sealing point. If the seat is worn in, the gasket no longer finds a flat surface.
Can the old seat be reworked?
We advise against it. Removing material changes the height of the sealing point – and with it the point at which the tap closes.
Does the seat also fit other La Marzocco models?
Our documentation explicitly names the KB90. For other models we carry separate items – send us the serial number and we'll find the right one.
Can I take a look at the part in your shop?
Yes. We're happy to show it to you in our showroom in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
